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 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 35  |  Issue : 3  |  Page : 115-126

Attention deficit hyperactivity disorder in a referred sample of school-aged children in Kuwait: sociodemographics, frequency, clinical presentations and impairments


1 Kuwait Centre of Mental Health, Sabah Medical Area, Kuwait
2 Department of Psychiatry, Faculty of Medicine, Suez Canal University, Ismailya, Egypt
3 Faculty of Medicine, Institute of Psychiatry, Ain Shams University, Cairo, Egypt

Date of Web Publication11-Nov-2014

Correspondence Address:
Hosam A Salem
MD, Kuwait Centre of Mental Health, Sabah Medical Area, Kuwait

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-1105.144323

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  Abstract 

Background
Although attention deficit hyperactivity disorder (ADHD) is one of the best-researched disorders in medicine, to our knowledge, there are no existing clinical studies on ADHD in Kuwait. This is the first study on ADHD in the state of Kuwait.
Aim of the work
The main aim of this study was to describe the clinical profile, frequency, sociodemographics, and impairments seen in patients with ADHD subtypes in a clinic-referred sample of school-aged children with ADHD in Kuwait.
Patients and methods
The sample consisted of 70 patients recruited from the child psychiatric outpatient clinic of the Kuwait Centre of Mental Health. The included patients had to fulfill the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. - text revision criteria - for ADHD and were between the ages of 6 and 15 years; patients of both sexes, Kuwaitis or expats, from all socioeconomic and educational backgrounds were included. All participants were initially screened using the Vanderbilt ADHD parent and teacher diagnostic rating scale and then subjected to a semistructured interview to verify the diagnosis of ADHD and apply the exclusion criteria. Wechsler Intelligence scale III was applied to rule out cases of intellectual disability (IQ score ≤70). The Mini International Neuropsychiatric Interview (MINI-KID) was performed to rule out cases with autism spectrum disorders and psychosis.
Results
This study showed that 71.4% of patients were male and 28.6% were female. The mean age of the patients was 10.2 (΁2.6) years. The most prevalent ADHD subtype was the ADHD-combined subtype (65.7%), followed by the ADHD-predominantly inattentive subtype (20%) and the ADHD-hyperactive impulsive subtype (14.3%). The ADHD-inattentive subtype was significantly more common among female patients and adolescents. The ADHD-hyperactive impulsive subtype was significantly more common among male patients and younger children. The ADHD-inattentive subtype showed a significantly older age of onset and presentation compared with the other two subtypes. In all, 51.4% of patients had a history of perinatal problems and 70% had a family history of ADHD. Patients in the sample were highly impaired functioning at both home and school; 90% failed to complete their homework, 68.6% disrupted classrooms, 12.9% were on probation or had been dismissed from school, 25.7% repeated a school grade, and 72.9% of patients had problematic relations with family members or peers.
Conclusion
The ADHD-combined type is the most prevalent subtype. The older mean age at presentation to the clinic compared with the mean age in similar studies may point to the critical lack of public awareness regarding ADHD or reluctance to refer children to the only psychiatric hospital in Kuwait. They suffer from impairments in many aspects of their lives that warrant attention in screening, management, and planning for service delivery as well.

Keywords: attention deficit hyperactivity disorder subtypes, attention deficit hyperactivity disorder, clinical profile, sex , Kuwait, sociodemographic


How to cite this article:
Salem HA, Fahmy M T, Youssef I M, Haggag W E, Muhamed A G, Radwan D N, Alkhadhari S. Attention deficit hyperactivity disorder in a referred sample of school-aged children in Kuwait: sociodemographics, frequency, clinical presentations and impairments. Egypt J Psychiatr 2014;35:115-26

How to cite this URL:
Salem HA, Fahmy M T, Youssef I M, Haggag W E, Muhamed A G, Radwan D N, Alkhadhari S. Attention deficit hyperactivity disorder in a referred sample of school-aged children in Kuwait: sociodemographics, frequency, clinical presentations and impairments. Egypt J Psychiatr [serial online] 2014 [cited 2021 Sep 28];35:115-26. Available from: http://new.ejpsy.eg.net/text.asp?2014/35/3/115/144323


  Introduction Top


Attention deficit hyperactivity disorder (ADHD) is the most common psychiatric disorder of childhood and adolescence. ADHD is also among the most prevalent chronic health conditions affecting school-aged children (Biederman et al., 2005). A review of prevalence rates in school-aged community samples indicates rates varying from 4 to 12%.

A recent study reviewed epidemiological studies on ADHD conducted from 1966 until 2009 in all Arab countries and concluded that epidemiological studies on psychiatric disorders are quite rare in the Arab world and that ADHD rates in Arab populations were similar to those in other cultures. Comparisons within Arab studies were difficult given the variability of methodology and instruments used (Farah et al., 2009). Results from Arab countries like Egypt (Magda et al., 2000), Oman (Al-Sharbati et al., 2004), and Qatar (Bener et al., 2006) reveal that ADHD appears to be more common among boys than among girls, with a ratio ranging from 3 : 1 in population studies to as much as 9 : 1 in clinic-referred studies. The worldwide prevalence of childhood ADHD is 5.2% (Polanczyk et al., 2007).

Not surprisingly, youths with ADHD constitute up to 50% of the child psychiatric clinic population (American Academy of Pediatrics, 2000). Recently, the Centers for Disease Control and Prevention estimated the rate of lifetime childhood diagnosis of ADHD in the USA as 9%, whereas only 4.3% (or only 55% of those with ADHD) had ever been treated with medication for the disorder (CDC, 2010).

Although ADHD usually first presents during childhood and the diagnosis of ADHD is most often made in children aged 6-12 years, many children with the disorder continue to experience symptoms as they enter adolescence (60-85%) and adult life (40%) (Pliszka, 2007). Estimates of adult ADHD prevalence averaged 4.4% (Kessler et al., 2006; Fayyad et al., 2007).

ADHD is associated with impairment in many areas of children's lives and is considered one of the leading causes of academic underachievement in schools as well as the cause of disruptive behaviors. Children with ADHD are more likely to use special educational services, as well as to be expelled, suspended, or to repeat a grade compared with controls (Loe and Feldman, 2007). ADHD is highly responsive to treatment with stimulants in combination with psychoeducational interventions. Delayed diagnosis and inadequate treatment of ADHD can lead to repeated school failure, antisocial behavior, road traffic accidents, family problems, delinquencies, and substance abuse (Pliszka, 2007).

Aim of the work

This study aimed to perform a comprehensive analysis of the sociodemographics, clinical characteristics, and frequency of ADHD subtypes in a referred sample of school-aged children with ADHD in Kuwait.


  Patients and methods Top


We conducted a descriptive study of a cross-sectional design at the outpatient child psychiatric clinic in Psychological Medicine Hospital, located at Alsabah Medical Area. It is the only psychiatry hospital in Kuwait and deals exclusively with all referrals from primary care centers, other tertiary hospitals, as well as self-referrals from the community. The catchment area covers all six governorates of Kuwait. The child psychiatric clinic works 3 days (Sunday, Tuesday, and Thursday) a week with an average of six to eight patients (one to two new referrals and five to six follow-ups) attending the clinic each day.

Selection of cases

The sample was recruited from consecutive referrals for psychiatric evaluations to the above-mentioned clinic during the study period (June 2010 to July 2011). This clinic sample was unselected in that children were referred for a general psychiatric evaluation and not for an evaluation of any specific disorder. Parents were approached for their informed consent and children's assent was taken as well to being interviewed and to participate in the study whenever their age permitted.

Inclusion criteria

All patients whose ages ranged between 6 and 15 years, of both sexes, who fulfilled the criteria for the diagnosis of ADHD according to the DSM-IV-TR diagnostic criteria were included.

Exclusion criteria

We excluded patients who had moderate to severe sensory deficits, such as visual and hearing impairment, or neurological handicaps and chronic medical conditions, or a history suggestive of severe head trauma or encephalopathy, or chronic disorders associated with medications that may affect behaviour, or evidence of comorbid pervasive developmental disorder, psychosis, or major depressive disorder with symptoms starting before ADHD or when ADHD symptoms occurred primarily during depressed episodes.

We also excluded patients with an intelligence quotient (IQ) score of less than 70, those who refused to give written informed consent for the study, and those with inadequate command of Arabic language.

During the 2 years of the study, we received 135 cases who fulfilled the required number of criteria of either inattention or hyperactivity-impulsivity plus impairment criteria as per the Vanderbilt ADHD rating scale. On performing the semistructured interview, 28 patients were found to have a pervasive developmental disorder, 10 had epilepsy uncontrolled on multiple antiepileptics, and two had severe hearing problems. On performing the structured interview, three patients were found to have mood disorder with psychotic features. On performing the Wechsler IQ test, 21 patients were found to have a total IQ below 70. One parent refused to give consent. In the end, we had 70 patients who were enrolled in the study.

Procedure

According to the American Academy of Child and Adolescent Psychiatry 'Practice Parameter for the Assessment and Treatment of Children and Adolescents with Attention Deficit Hyperactivity Disorder' (Pliszka, 2007), assessment of ADHD and comorbid disorders was carried out as follows:

Screening for ADHD: the Arabic version (Alqahtani, 2009) of the Vanderbilt ADHD Diagnostic Parent Rating Scale (VADPRS) (Wolraich et al., 2003):

The Vanderbilt rating scale is a highly reliable and valid narrow band screening tool that directly follows the DSM-IV-TR criteria and has been widely used for screening for ADHD in several recent studies investigating ADHD and comorbid disorders (Laslie, 2005; Alqahtani, 2009). The Vanderbilt diagnostic rating scale uses a four-point Likert rating, in which a respondent notes whether 18 specific behavior symptoms of ADHD occur rarely, sometimes, often, or very often. A child meets behavioral criteria for the inattentive subtype if at least six of the nine inattentive items are scored as often or very often by the respondent, for the hyperactive/impulsive subtype if at least six of the nine hyperactive/impulsive items are scored, and for the combined subtype if at least six of each of the two sets of items are scored. The VADPRS also addresses functional impairment with respect to relationships with family and peers, as well as academic performance.

All new patients referred to the clinic, regardless of their initial complaints, were routinely screened for ADHD by asking the attending parent to complete the VADPRS including the 18 DSM-IV symptoms of ADHD and the impairment section of the VADPRS in the waiting room before the psychiatric interview was carried out. The comorbidity section was not used in this study because in a previous study VADPRS could not differentiate between anxiety and depression (Laslie, 2005) [60].

Patients screened positive (6 ≥ 9 in any or both of the inattention and/or hyperactivity impulsivity domains plus impairment in two settings) were considered to have 'possible ADHD'.

Semistructured psychiatric interview was carried out next to verify the diagnosis of ADHD, to gather sociodemographic data, and to identify for exclusion criteria.

A detailed psychiatric history was taken by the investigator for all patients screened positive for ADHD, guided by the child psychiatry sheet of the Neuropsychiatry department, Ain Shams University. This sheet was validated through its use in previous studies and covers the following areas.

Full medical and psychiatric history was obtained to identify exclusion criteria, birth problems, developmental milestone abnormalities, family history, social problems, and history of present illness. Assessment of onset, duration, and severity of each of the 18 symptoms of ADHD as well as symptoms of other comorbid conditions was carried out.

Details about the onset of ADHD symptoms, onset of other comorbid disorders, and pervasiveness of symptoms and impairment were especially recorded by the researcher.

The Arabic version of the Wechsler Intelligence Scale for Children II (Wechsler, 1991)

This is a standardized test used in this study to exclude cases of mental retardation. It is divided into six verbal and five performance subtests. The mean administration time to complete the test is 60-90 min. The verbal and performance IQ is tested and a composite full-scale IQ score is computed. The full version of the test was administered by a clinical psychologist working in the Psychological Medicine Hospital. This version was validated for use in Kuwait in 1998.

Assessment of comorbidities according to the Arabic version (Ghanem et al., 2000) of the Mini International Neuropsychiatric Interview (MINI-KID) (Sheehan et al., 1998)

The MINI-KID is a highly reliable and valid structured diagnostic interview tool used in this study to systematically verify comorbid disorders (23 DSM-IV and ICD-10 childhood psychiatric disorders). MINI-KID uses branching logics to reduce the number of questions asked to only those necessary to determine the presence or absence of each condition. The administration time of the MINI-KID is 15 min (Sheehan et al., 1998).

The researcher interviewed young school-aged children (6-8 years old) in the presence of their parents. Questions were directed to the child, but the parent was encouraged to intercept if she or he felt that the child's answers were unclear or inaccurate.

Older children and adolescents were interviewed separately from parents, as older children and teenagers may not reveal significant symptoms (depression, suicide, or drug or alcohol abuse) in the presence of a parent.

Statistical analysis

All data were collected, verified, revised, and edited using a statistical package on a compatible computer. The data were then analyzed statistically using the statistical package for social science version 17. The following tests were carried out.

χ2 -test: a statistical tool used to test for significant difference between more than two independent qualitative portions.

Student's t-test: a statistical tool used to test for the significance of comparison between the means of two quantitative variables.

One-way ANOVA: a statistical tool used to test for the significance of comparison between means of more than two quantitative variables.

P value: a value used to indicate the level of significance. P values greater than 0.05 were considered insignificant, P values less than 0.05 were considered significant, P values greater than 0.01 were highly significant, and P values less than 0.001 were considered very highly significant.

Ethical considerations

(1) Ethical approval was taken from the Medical Research Committee in the psychological medicine hospital.

(2) Informed consent: written informed consent from the attending parent and oral assent of the child were taken. Parents who signed the informed consent form were asked to request the school teacher with greatest awareness about the child to complete the VADPRS and to return it to the researcher. If the teacher could not complete such a rating scale or the parent refused to contact the school, then materials from the school, such as work samples or report cards, were reviewed.


  Results Top


Sociodemographic characteristics of the sample

The sample consisted of 70 patients, all with a current diagnosis of ADHD according to DSM-IV. [Table 1] shows some demographic characteristics of the sample: 71.4% were male and 28.6% were female; the mean age of the patients was 10.19 (SD 2.55) years; the mean age of boys was less than that of girls (9.92 vs. 10.85). The proportion of girls among adolescents presenting to the clinic with ADHD was 45% (n = 9/20), which was more than double their proportion among children (22%) (n = 11/50). Patients presenting to the children's clinic came from all governorates of Kuwait: 25.7% lived in semiurban governorates (Jahra and Ahmady) and 74.3% lived in urban ones (Farwaneya, Capital, Mubarak Alkabir, and Hawally).
Table 1 Sociodemographic characteristics of the attention deficit hyperactivity disorder patients in the Kuwaiti sample

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Nearly 45.7% (n = 32) of patients were Kuwaitis, 40% (n = 28) were Egyptians, and 14.3% (n = 10) were of 'other nationalities', including three stateless (Bedoons), three Syrians, one Lebanese, one Palestinian, one Saudi, and one Iraqi.

The mean age of the Egyptian patients was 9.41 years (±2.35), which was the lowest, followed by Kuwaiti patients [10.47 (±2.57) years] and then other nationalities [11.45 (±2.60)]. Among the patients, 38.6% (n = 27) were the oldest among the children in the family, 25.7% (n = 18) were the youngest, and 35.7% (n = 25) were 'other' orders of birth.

Family history

As seen in [Figure 1], 70% (n = 49) had a family history of ADHD, 21.4% (n = 15) had a family history of anxiety, 21.4% (n = 15) had a family history of depression, and 12.9% (n = 9) had a family history of legal problems or substance use disorder.
Figure 1: Family history of attention defi cit hyperactivity disorder (ADHD), anxiety, depression, and legal problems or substance abuse in the sample by percen tage.

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Parental education

The proportion of parents with a university or higher level of education was greater among patients who presented at a younger age (children 6-12 years old) than among patients who presented later in adolescence (12-15 years old) (84.2 vs. 15.8% for fathers and 75.6 vs. 24.4% for mothers). This difference was statistically significant only for fathers (fathers: P = 0.01; mothers: P = 0.357), as shown in [Table 2].
Table 2 A comparison of parental educational among children and adolescents

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Perinatal problems

As shown in [Table 3], 51.4% of patients (n = 36) had a history of perinatal problems. The three most common perinatal problems in the sample were prematurity [21.4% (n = 15)], followed by obstructed labor and maternal stress during pregnancy [15.7% (n = 11) each].
Table 3 Frequency of perinatal problems, delayed developmental milestones, social problems, and impaired functioning at school and home among patients with attention deficit hyperactivity disorder

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Developmental delays

As shown in [Table 3], 30% (n = 21) of the sample had a history of delay in achieving developmental milestones. Delay in acquiring speech was the most common (15.7%), followed by sphincteric control delay (8.6%) (n = 6). Of the children, 5.7% (n = 4) had a history of delayed milestones in more than one domain. None of the patients had a history of only motor delay.

Social problems

As shown in [Table 3], the proportion of ADHD patients having at least one social problem was 75.7% (n = 53); 65.7% (n = 46) witnessed domestic violence, including verbal or physical aggression between parents, 30% had divorced parents, 24.3% (n = 17) were physically abused on a regular basis by one or both parents, 5.7% (n = 4) had been victimized at school by school teacher(s) or by other students, and 5.7% (n = 4) had one deceased parent.

Impairment at home and school in the sample

All patients in the sample had impaired functioning at both home and school; 72.9% (n = 51) of patients with ADHD had problematic relations with family members or peers, 90% (n = 63) failed to complete the homework requested by teachers, 68.6% (n = 48) disrupted classrooms and had their parents called to school to discuss their improper behavior, 12.9% (n = 9) were on probation or had been dismissed from school, and 25.7% (n = 18) had repeated a school grade, as shown in [Table 3].

Clinical profile of attention deficit hyperactivity disorder subtypes

Frequency of attention deficit hyperactivity disorder subtypes

0As shown in [Figure 2], the ADHD-combined subtype was the most common [65.7% (n = 46)], followed by the ADHD-inattentive subtype [20% (n = 14)] and then the ADHD-hyperactive impulsive subtype [14.3% (n = 10)].
Figure 2: Frequency of attention defi cit hyperactivity disorder (ADHD subtypes in the sample (N = 70).

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Sex distribution of attention deficit hyperactivity disorder subtypes

As shown in [Table 4], on comparing the frequency of ADHD subtypes among boys and girls, the ADHD-combined type predominated in both sexes (70 and 55%, respectively). The ADHD-inattentive type was more common among girls than among boys (45 vs. 10%). None of the girls presented with ADHD-hyperactive impulsive subtype, compared with 20% of boys. This difference was statistically significant (P = 0.001).
Table 4 Sex, age group, mean age of onset, and mean age of presentation in relation to attention deficit hyperactivity disorder subtypes

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Age distribution of attention deficit hyperactivity disorder subtypes

As shown [Table 4], among the children aged 6 to below 12 years, the ADHD-combined type was the most common (74%), followed by the ADHD-Hyperactive impulsive subtype (18%) and then the inattentive subtype (8%). In contrast, among adolescents (12-15 years old), the ADHD-Inattentive subtype was the most common (50%), followed by the combined subtype (45%) and then the hyperactive impulsive subtype (5%). This difference was statistically significant (P = 0.001).

Age of onset and presentation of attention deficit hyperactivity disorder according to attention deficit hyperactivity disorder subtype

As shown in [Table 4], on comparing the mean age of onset of ADHD according to ADHD subtypes, it was seen that patients presenting with the ADHD-inattentive subtype were the oldest age at onset [3.96 (±0.84) years], followed by patients with the ADHD-combined subtype [3.03 (±1.46) years] and then those with the ADHD-hyperactive impulsive subtype [2.70 (±1.49) years]. This difference was statistically significant (P = 0.047).

Similarly, on comparing the mean age at presentation of patients with ADHD according to ADHD subtypes, it was seen that patients presenting with the ADHD-inattentive subtype were the oldest [12 (±2.26) years], followed by those presenting with the ADHD-combined subtype [10.08 (±2.22) years] and then those with the ADHD-hyperactive impulsive subtype [8.15 (±2.59) years]. This difference was statistically significant (P = 0.001), as shown in [Table 4].

[Figure 2] shows that the pattern of impairment among patients with the ADHD-inattentive subtype was different from the other two subtypes. Patients with the ADHD-inattentive subtype were more likely to repeat school grade (χ2 = 6.0, d.f. = 1, P = 0.05), less likely to disrupt class (χ2 = 18.0, d.f. = 2, P = 0.00), and less likely to have a problematic relationship with family/peers (χ2 = 0.78, d.f. = 2, P = 0.67) [Figure 3].
Figure 3: Patterns of impairment of functioning according to attention deficit hyperactivity disorder (ADHD) subt ypes.

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  Discussion Top


Although ADHD is one of the best-researched disorders in medicine (Pliszka, 2007), studies on ADHD from Arab and other developing countries are scarce (Farah et al., 2009), despite the preponderance of youth in their communities (Fayyad et al., 2001; Al-Sharbati et al., 2004; Bener et al., 2006). The case is similar in Kuwait where youths under the age of 15 years constitute 39.9% of the 1.1 million Kuwait population (Ministry of Planning of the state of Kuwait, 2006). To our knowledge, there are no existing clinical studies on ADHD in Kuwait. This is the first such study among Kuwaiti students.

The aim of this research was to perform a comprehensive analysis of a sample of referred school-aged children and adolescents with ADHD in Kuwait, to study the clinical characteristics of ADHD, and report the frequencies of its subtypes. This was carried out through a descriptive, cross-sectional study design.

Sociodemographic characteristics

Age and sex of the sample

Our results revealed that 71.4% of the clinical sample was male and only 28.6% was female (i.e. 2.5 : 1), which was in accordance with the results of several studies showing a male predominance in ADHD. Curran et al. (2000) found that boys are two to three times more affected than girls, which was further supported by Aydin et al. (2010) in a sample of Turkish children and by other studies in the Arab world [Bu-Haroon et al. (1999) in Sharjah; El Sheikh et al. (2003) in an Egyptian sample]. Fayyad et al. (2001) found that the male to female ratio of ADHD in a Lebanese sample was 3 : 1. This higher rate of males in a clinical setting can be explained by referral bias: boys are more likely than females to exhibit aggressive and antisocial behavior and therefore more likely to be referred for treatment at a psychiatric clinic. In contrast, girls with ADHD are more likely than boys to have the inattentive form of ADHD and less likely to show obvious problems. Some studies postulated that girls, in comparison with boys, need more familial risk factors to develop ADHD, called a 'familial dose model' (Faraone et al., 2003).

The mean age of the sample was 10.2 years (SD 2.5), which is older than the mean age of ADHD patients referred to the outpatient clinic in many other studies, which ranged from 8 to 9 years (Biederman et al., 2002; Gershon, 2002; Khalil et al., 2010). This delayed presentation of cases of ADHD to the outpatient clinic may reflect the lack of public knowledge about ADHD in Kuwait or may point to the reluctance of parents to refer and open a file for their children in the only psychiatric hospital in Kuwait.

Children (6 to <12 years of age) constituted 71.4% of the sample, compared with 28.6% of adolescents (12-15 years old). These results are in accordance with those of other studies that showed that ADHD is a chronic mental disorder that starts in early childhood and symptoms persist into adolescence and adulthood in 60% of patients, with 4-5% of adults still carrying the disease (Kessler et al., 2006).

The results further revealed that sex distribution was different among children presenting between the ages of 6 and 12 years compared with older patients who present between 12 and 15 years (adolescents); the proportion of female patients among adolescents was more than double the proportion among children (45 and 22%, respectively). The ratio of male to female patients among adolescents in our sample was 1.2 : 1. This result is in accordance with recent studies showing that there is no significant sex-related difference in ADHD prevalence among adolescents and adults (National Institute for Health and Clinical Excellence (NICE), 2008; Schmidt and Petermann, 2009; Wilens et al., 2010; Soreff et al., 2012). Similarly, a recent study that assessed the prevalence of ADHD and comorbid psychiatric disorders in sample of 2000 Egyptian college students aged above 18 years from Tanta University reported the ratio of men to women as 1.4 : 1 (El-Hay and El Sawy, 2011).

Residency, nationality, and parental education

Patients came from all six governorates of Kuwait; 45.7% were Kuwaitis, 40% were Egyptians, and 14.3% were of other nationalities. According to the Ministry of planning in Kuwait (2006), Egyptians are the second most common expatriates in Kuwait, only superseded by Indians. The majority of Egyptians are skilled workers who live with their families in Kuwait.

The proportion of Egyptian parents with university or higher level of education was greater than that of Kuwaitis and people of other nationalities (82 vs. 40 vs. 20% for fathers' education and 78 vs. 53 vs. 20% for mothers' education, respectively). As parents' complaints are often the reason for the referral of a child with ADHD (Barkley, 2011), the over-representation of Egyptians in the sample may reflect the increased awareness of the disorder among Egyptian parents due to higher educational status, their desire for medical intervention, their concern over the scholastic and academic achievement of their children, and their ability to handle the stigma attached to referral to a psychiatric outpatient clinic in comparison with parents with relatively lower education.

This postulation was further supported by our finding that patients with parents having university or higher level of education, regardless of nationality, presented significantly more frequently at a younger age (children 6 to <12 years old) compared with patients whose parental education was high school or below (84 vs. 56%, respectively) (P = 0.01). Furthermore, compared with Kuwaiti families, Egyptian families have fewer children, smaller area of homes, and more contact between parents and their children, allowing for earlier recognition of the problem and earlier approach for treatment.

Family history

Seventy percent of patients in the sample had a family history of ADHD symptoms; 21.4% had a family history of anxiety, 21.4% had a family history of depression, and 13% had a family history of legal problems or substance use disorders. This high frequency of ADHD among relatives of patients with ADHD is in accordance with the findings of Faraone et al. (2005b) who reviewed 20 independent twin studies and estimated the heritability of ADHD (i.e. the amount of phenotypic variance of symptoms attributed to genetic factors) to be 76%, which shows that ADHD is the most heritable psychiatric disorder. Even more striking is the finding that if a parent has ADHD the risk for the offspring is 57% (Biederman et al., 1995). Further evidence for the familial clustering of ADHD in families of affected children came from a study by Smalley et al. (2000) in which they assessed 256 parents in families with two or more patients with ADHD for various psychiatric disorders and found that 55% of the families had at least one parent with a lifetime diagnosis of ADHD.

Our findings as regards family history of anxiety, depression, and legal problems or substance use agree with the results of a study on 59 biological parents of children with ADHD in which 17.9% of the parents reported major depression and 21% reported an anxiety disorder (McCormick, 1995). However, the proportions seen in our study in this regard are lower than those reported by a recent study in Iran, which found rates of depression among parents of children with ADHD to be 44 and 31%, respectively. This difference, however, may be because they used a structured interview to determine the current and lifetime psychopathology of the parents (Ghanizadeh et al., 2008).

Family loading for anxiety and depression may influence child ADHD internalizing comorbidity. Parental antisocial behavior and substance abuse are associated with child externalizing behaviors such as aggression and delinquency (Connor, 2002).

Perinatal problems

As regards perinatal problems, 51.4% of patients had a history of at least one perinatal complication, including prematurity in 21.4%, maternal stress during pregnancy and obstructed labor in 15.7% each, postnatal jaundice in 12.9%, and postnatal hypoxia, incubation, or mother having a medical illness or receiving medications during pregnancy other than routine medications in 11.4% each. Less common perinatal problems were bleeding during pregnancy in 7.1%, maternal smoking during pregnancy in 4.3%, and preeclampsia in 2.9%.

The results are in accordance with those of Fayyad et al. (2001) who found that 40.2% of his sample of Lebanese children with ADHD had at least one known perinatal risk factor. Moreover, our results recognized prematurity as the most common perinatal complication in the sample. This is in accordance with other studies showing that, although certain pregnancy complications may not be the cause of most cases of ADHD, some cases may arise from such complications, especially from prematurity associated with minor bleeding in the brain. Children born prematurely are at high risk for later hyperactivity or ADHD (Breslau et al., 1996; Nigg, 2006).

Developmental delays

Thirty percent of our sample had a history of delay in developmental milestones; the most common was delayed speech in 15.7%, followed by sphincteric control delay in 8.6% and finally delayed milestones in more than one domain in 5.7%. These findings agreed with the results of a study conducted by Szatmari et al. (1989), who found children with ADHD to be somewhat more likely than typical children to have a delayed onset of talking during early childhood.

Our results also agreed with the results of a recently published cross-sectional study conducted in the USA on more than 61 779 children and adolescents aged 6-17 years old, including 5028 patients with ADHD, which showed that history of delayed speech was present among 12% of patients with ADHD compared with 3% of patients without ADHD. Although children with ADHD do not appear to have a high rate of serious or generalized language delays, they are more likely to have problems in their speech development than are children without ADHD (Larson et al., 2011).

Impairment

Our results showed that all patients with ADHD had impaired functioning at both home and school: 72.9% of patients with ADHD had problematic relations with family members or peers, 90% failed to complete the homework requested by teachers, 68.6% disrupted classrooms and had their parents called to school to discuss their improper behavior, 12.9% were on probation or had been dismissed from school, and 25.7% had repeated a school grade. These results are important in showing that patients included in this study had impaired functioning at both home and school as required by DSM-IV-TR for the diagnosis of ADHD. A recent study found a higher rate of grade repetition among patients with ADHD compared with other children (29 vs. 9%) (Larson et al., 2011).

Social problems

Our results recognized the high incidence of social problems among patients with ADHD: 75.7% of patients had at least one social problem; almost two-thirds (65.7%) of patients witnessed domestic violence (including verbal or physical aggression between parents), 30% had divorced parents, 24.3% were physically abused on a regular basis by one or both parents, 5.7% were victimized at school by teacher(s) or other students, and 5.7% had one deceased parent.

Clinical profile of attention deficit hyperactivity disorder subtypes

Frequency of attention deficit hyperactivity disorder subtypes

The results revealed that the ADHD-combined subtype was the most common ADHD subtype (65.7%), followed by the inattentive subtype (20%) and the hyperactive impulsive subtype (14.3%). This was in agreement with the results of several researchers who found that the ADHD-Combined type was the most common, followed by the inattentive type and the hyperactive-impulsive type among clinic-referred ADHD children. Byun et al. (2006) found the ADHD combined type to be present in 66.7% of patients in his clinic-referred Korean sample, followed by the inattentive subtype in 21% and the hyperactive impulsive subtype in 12.3%. Our findings were also similar to a study by Al-Sharbati (2004), in which he found 68% of his clinic-referred Omani sample to meet the criteria for combined type, 20% for the inattentive type, and 12% for the hyperactive impulsive type. Fayyad et al. (2001) found 77% of his clinic-referred Lebanese sample to meet the criteria for the combined subtype, 18% for the predominantly inattentive subtype, and 5% for the predominantly hyperactive impulsive subtype. The prevalence of ADHD subtypes in the clinic-referred sample in Kuwait is not much different from that of other Arab and industrialized countries.

Sex distribution of attention deficit hyperactivity disorder subtypes

The results of the study showed that, although the ADHD-combined subtype was the most prevalent type among both male (70%) and female (55%) patients, the ADHD-inattentive subtype was significantly more prevalent among female patients (45%) than among male patients (10%) and the ADHD-hyperactive impulsive subtype was more prevalent among male patients (20%) than among female patients (0%) (P = 0.001).

Our results were almost identical to the results of a landmark study that investigated sex differences in ADHD among children in clinic referrals. The study included 140 boys and 140 girls with ADHD and 120 boys and 122 girls without ADHD who were assessed with structured diagnostic interviews and neuropsychological batteries. The results of this study showed that, although the combined subtype was the most common subtype in both sexes, girls with ADHD were more likely than boys to have the predominantly inattentive type of ADHD and boys were more likely to have the hyperactive-impulsive subtype (Biederman et al., 2002). As symptoms of inattention are more covert than those of hyperactivity and impulsivity, the higher rate of these symptoms in girls with ADHD than in boys with ADHD may partially explain the markedly higher male to female ratios in groups of children who are clinically referred for ADHD.

Age distribution of attention deficit hyperactivity disorder subtypes

The results of the research showed a statistically significant difference (P = 0.001) in the mean ages of presentation of patients with ADHD according to ADHD subtypes: patients with the inattentive subtype were the oldest, the hyperactive-impulsive subtype the youngest, whereas the combined subtype were intermediate in age. Similar age patterns were detected in other studies (MTA Cooperative Group, 1999; Biederman et al., 2002; Byun et al., 2006).

Furthermore, our results showed different distribution of ADHD subtypes among children (6 to <12 years old) and adolescents (12-15 years old). Among children the ADHD-combined type was the most common (74%), followed by the ADHD-hyperactive impulsive subtype (18%) and then the inattentive subtype (8%). In contrast, among adolescents the ADHD-inattentive subtype was the most common (50%), followed by the combined subtype (45%) and then the hyperactive-impulsive subtype (5%) (P = 0.001). Our age findings regarding the ADHD subtypes are in accordance with the results of a recent study conducted in Switzerland by Ramelli et al. (2010) who reported the presence of age-dependent differences in presentation of ADHD in a clinic-referred sample of 97 Swiss children and adolescents. Their results showed that in preschoolers the ADHD-hyperactive impulsive subtype is the most common (50%), in primary school children the ADHD-combined subtype is the most common (65%), and in adolescents the ADHD-inattentive subtype is the most common (67%).

Similarly, findings on age-related effects in a study by Nolan et al. (2001) were consistent with our results in showing that younger children had higher rates of hyperactivity-impulsivity, whereas older children and adolescents had higher inattention rates. This age pattern is also in accordance with longitudinal studies of ADHD, which showed that the symptoms of inattention remain more stable across middle childhood into early adolescence, whereas those for hyperactive-impulsive behavior decline more steeply over this same time period (Hart et al., 1995; DuPaul et al., 1998; Kessler et al., 2010).

Age of onset and presentation of attention deficit hyperactivity disorder according to subtype

Our results showed that the mean age of onset of ADHD (3.17 years old) varied according to ADHD subtype; ADHD-inattentive subtype had a significantly older mean age of onset (3.96 years) compared with the ADHD-combined subtype (3 years old) and the ADHD-hyperactive impulsive subtype (2.7 years old) (P = 0.047). These results are in accordance with those found in a recent review of the literature (Barkley, 2011), which indicated that ADHD symptoms often appear during preschool years, typically at ages 3-4 years (Taylor et al., 1991; Loeber et al., 1992; Applegate et al., 1997), and, more generally, by entry into formal schooling. The age at onset is heavily dependent on the type of ADHD under study. The first to appear is the pattern of hyperactive-impulsive behavior, giving that subtype the earliest age of onset, followed by the combined type (Hart et al., 1995) and then the inattentive subtype (Applegate et al., 1997).

The results of the present study showed that the mean age at presentation to the clinic varied according to ADHD subtype. Patients with the ADHD-inattentive subtype had a highly significant older mean age (12 years old) compared with patients with the ADHD-combined subtype (10.08 years old) and the ADHD-hyperactive impulsive subtype (8.15 years old) (P = 0.001). These results are in accordance with the results of a study that investigated the clinical correlates of ADHD subtypes, which showed that the age of presentation of the ADHD-inattentive subtype was significantly higher than that of the other two subtypes (Weiss et al., 2003).

This later age of presentation of the ADHD-inattentive type in early adolescence, together with the longer interval between onset of symptoms and presentation to the clinic, compared with the other subtypes, may be because adolescents in high school have a higher cognitive load compared with children in lower grades; hence, it is not surprising that the inattentive symptoms become more problematic as one reaches adolescence.

Impairment according to attention deficit hyperactivity disorder subtype

The results of the present study showed that the pattern of impairment among patients with the ADHD-inattentive subtype was different from the other two subtypes. Patients with the ADHD-inattentive subtype were more likely to repeat school grade (P = 0.05) and significantly less likely to disrupt class (P = 0.00) and to have a problematic relation with family/peers (P = 0.67). These results agree with those of previous studies that investigated the correlates of ADHD subtypes and showed that patients with the ADHD-inattentive subtype had higher rates of academic problems (Loe and Feldman, 2007) and lower rates of behavioral and social problems with family and peers compared with other subtypes of ADHD (Weiss et al., 2003). These results are logical because inattention observed in ADHD is related to problems in the executive functioning of the brain, such as working memory, sustained attention, verbal fluency, planning, and problem solving needed for academic work (Brown, 2009).

Emperical investigation indicates that inattention, not the hyperactivity-impulsivity symptom dimension, is related to poor academic performance as well as to poor performance on neuropsychological and cognitive tests of attention (Willcutt et al., 2005). Numerous well-controlled medication studies have shown that simulants (Faraone et al., 2007) and the nonstimulant atomoxetine (Wigal et al., 2005) enhance a variety of cognitive processes important for academic work through the regulation of attention focus, processing speed, working memory, inhibition of impulsive responding, and motivation on doing tasks that are not intrinsically interesting to the individual (Brown, 2009).

To sum up, the clinical sample consisted of ADHD children and adolescents with male predominance; the proportions of ADHD subtypes were in accordance with other studies based on clinic-referred samples. The age of onset, presentation, sex distribution of ADHD subtypes, family history, and perinatal and developmental histories were in agreement with many epidemiological studies carried out on ADHD children, indicating that the sample is representative of clinic-referred ADHD patients and is suitable for further conclusions to be drawn from the subsequent results.

Limitations

Despite its findings, this study has some limitations. First of all, this study is not a longitudinal follow-up, but rather cross-sectional in nature. If the study had been followed up longitudinally, more accurate observations with respect to comorbidity and clinical characteristics could have been reported. Therefore, a longitudinal design would be beneficial in further studies. Moreover, our assessments relied on parental reports and direct interviews with children but did not include information collected from teachers. This limitation is not likely to affect the findings presented here because (a) we encouraged parents to report any complaints from school teachers and all patients had impaired functioning at both home and school; in addition, (b) we reviewed school reports and sample of school works.


  Conclusion Top


The ADHD-combined type is the most prevalent subtype. The older mean age at presentation to the clinic compared with the mean age in similar studies may point toward the critical lack of public awareness regarding ADHD or the reluctance to refer children to the only psychiatric hospital in Kuwait. They suffer from impairments in many aspects of their lives that warrant attention in screening, management, and planning of service delivery as well.


  Acknowledgements Top


Ethical adherence was maintained all through the work.

 
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    Figures

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    Tables

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