|Year : 2022 | Volume
| Issue : 3 | Page : 140-148
Assessment of risk factors in children suffering from obsessive–compulsive disorder
Shaimaa Saied1, Ashraf El-Tantawy2, Wafaa Haggag2, Khaled Abd Elmoez2, Haydy Hassan2
1 Department of Psychiatry, Suez Canal Authority, Egypt
2 Department of Psychiatry and Neurology, Faculty of Medicine, Suez Canal University, Suez Canal, Egypt
|Date of Submission||19-Mar-2022|
|Date of Decision||10-Apr-2022|
|Date of Acceptance||02-May-2022|
|Date of Web Publication||16-Dec-2022|
PhD Haydy Hassan
Department of Psychiatric and Neurological Diseases, Faculty of Medicine, Suez Canal University, Ismailia City
Source of Support: None, Conflict of Interest: None
Background Obsessive–compulsive disorder (OCD) is a debilitating illness. The exploration of risk factors of obsessive–compulsive in childhood will offer a different perspective in order to reduce the prevalence of lifelong OCD.
Aim of the study This study assessed some risk factors of OCD in a sample of children suffering from OCD, which included history of stressful and/or traumatic life events, positive family history of OCD, pattern of parenting styles, and evidence for post-streptococcal infection.
Methods The study was conducted as a cross-sectional comparative study, targeting school-age children (6–12 years old) who suffered from OCD in comparison with typically developing age-matched and sex-matched normal children.
Results Statistically significantly differences were detected between histories of trauma exposure, anti-streptolysin O titer, and authoritarian parenting styles among the OCD children, in comparison with those of healthy controls.
Conclusion Authoritarian parenting style and trauma exposure, particularly of emotional abuse, were established as the most risk factors for developing childhood OCD.
Keywords: children, obsessive–compulsive disorder, risk factors
|How to cite this article:|
Saied S, El-Tantawy A, Haggag W, Abd Elmoez K, Hassan H. Assessment of risk factors in children suffering from obsessive–compulsive disorder. Egypt J Psychiatr 2022;43:140-8
|How to cite this URL:|
Saied S, El-Tantawy A, Haggag W, Abd Elmoez K, Hassan H. Assessment of risk factors in children suffering from obsessive–compulsive disorder. Egypt J Psychiatr [serial online] 2022 [cited 2023 Dec 10];43:140-8. Available from: https://new.ejpsy.eg.net//text.asp?2022/43/3/140/363991
| Introduction|| |
Obsessive–compulsive disorder (OCD) is one of the most chronic and disabling psychiatric disorder with a lifetime prevalence of 2–3% in the general adult population (Ruscio et al., 2010). The onset of the first obsessive–compulsive symptom (OCS) occurs during childhood in the majority of cases (De Mathis et al., 2013). However, data on the prevalence of OCD among children and adolescents are scarce. Available prevalence estimates range from 0.1 to 3.6% for pediatric-onset OCD, which is highly underdiagnosed and 90% of affected children are left untreated (American Academy of Child and Adolescent Psychiatry AACAP, 2012). The prevalence of OCS among a community sample of Egyptian students was 15.5%, with 2.2% of them who fulfilled the Diagnostic & Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR) criteria for OCD (Rady et al., 2013).
Inspite of a range of compelling theories and considerable research, the etiology of developing pediatric OCS and/or OCD remains relatively poorly understood, and no definitive cause can be yet identified. OCD is believed to result from a combination of neurobiological, genetic, environmental, cognitive, or behavioral factors that combine within a specific individual at a certain time point to trigger onset of the illness (Nestadt et al., 2000).
In OCD, either stress may lead directly and causally to the development of symptomatology through a specific vulnerability, or the disorder may exist independently, but exacerbated by stressful life events that precipitate its onset (Real et al., 2011). Environmental triggers include childhood trauma that has been linked to specific neurobiological changes, and associated with an increase in the risk of developing many psychiatric disorders, including OCD (Brander et al., 2016). A significant association was reported between high levels of OCS and childhood trauma, specifically of emotional abuse and physical neglect, and similarly between OCS and conscientiousness, and between conscientiousness and emotional neglect, or sexual abuse, suggesting an indirect role of childhood trauma in the development of OCS (Mathews et al., 2008).
The OCD may be linked to behavior-related habits that one learns over time, or a result of developing learned negative thoughts and behavior patterns, toward neutral situations, which can result from previous life experiences (Zohar and Felz, 2001). Social factors are influences in the social environment that help in developing and sustaining the OCS. Family accommodation of OCS has been found to be common in pediatric OCD, as it has been suggested that the parent’s response to their child’s behavior and the way by which they react, can affect the OCS by either increasing or decreasing the child’s anxiety (Geller, 2010).
In addition and according to the social learning theory that learning occurs within the general familial environment, from observing, modeling, and imitating the attitudes, reactions, and behaviors of others (Vasey and Dadds, 2001; McCullough, 2011). Parents can either provide an environmental context that influences the development of anxiety traits (as by frequent criticism), or reinforce the children’s experiences of anxiety. It has been proposed that parenting styles may play a significant role in the development and maintenance of different behavioral and psychiatric disorders, such as childhood anxiety (Matejevic et al., 2014). Researchers have concluded that four types of parenting styles were determined as follows: the authoritarian, authoritative, permissive, and uninvolved (Barnhart et al., 2013; Matejevic et al., 2014).
Clinical observations and systematic investigations have suggested a possible role of immune dysregulation in the pathophysiology of childhood OCD that was originally based on the association between infection by group-A beta-hemolytic streptococci (GABHS), and the abrupt onset and subsequent exacerbations of OCD in a subgroup of children. The obsessive thoughts, compulsive behaviors, and motor or vocal tics appeared ‘overnight and out of the blue’ and usually reached full-scale intensity within 24–48 h (Teixeira et al., 2014).
Biological triggers may include a child’s immune-system response to illnesses as in the case of streptococcal bacterial infection that affects the throat and tonsils. Clinical observations and systematic investigations have shown that a subgroup of children with OCD and/or tic disorders experiences the onset and subsequent exacerbations of their symptoms following infections with group-A beta-hemolytic streptococci (GABHS), which was called PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcus) (Snider and Swedo, 2003; Martino et al., 2009).
So, this study is aimed at assessment of some risk factors of OCD in children. The study hypotheses are history of stressful and/or traumatic life events is a risk factor in developing OCD in children, different patterns of parenting styles can strongly affect developing of OCD in children, positive family history for OCD is a risk factor in developing OCD in children, and there are significant relations between post-streptococcal infection and OCD in children.
| Patients and methods|| |
Type of study: a cross-sectional comparative study.
Study setting: Childhood Psychiatry Clinic in Suez Canal University Hospital, Suez Canal Authority, and El-Matafy Psychiatric Outpatient Clinic in Ismailia.
Case group: 40 school-age children (6–12 years old) who suffered from OCD according to DSM-5.
Control group: another 40 typically developing children that do not suffer from any psychiatric symptoms and their age and sex matched to the studied group. They were selected from pediatric clinics.
The study excluded children diagnosed with organic brain lesions or medical or neurological disorder, such as Sydenham’s chorea, systemic lupus erythematous, Tourette disorder. Also, children diagnosed with autistic spectrum disorder or had intellectual disabilities were excluded from the study.
Psychiatric interviews were held for parents and children, including history-taking questionnaire, history of stressful and/or traumatic life events [other than post-traumatic stress disorder (PTSD)], and a thorough review of the medical history. Parents were assessed for their parenting styles, lifetime history of OCD, and other psychiatric disorders, with detailed family psychiatric history of each parent.
The aim of the study and adequate explanation of the work to the participants was done primarily, and informed written consents have been obtained from parents, prior to inclusion in the study.
The following diagnostic tools and instruments were applied as follows:
- DSM-5 Diagnostic Criteria: for OCD diagnosis (American Psychiatric Association, 2013).
- Family history of OCD or other psychiatric disorders: detailed family psychiatric history was obtained about each parent and the other siblings, including lifetime history of OCD, as well as other psychiatric disorders.
- History of stressful and/or traumatic life events: both children and caregivers were inquired about the history of any stressful or traumatic life events before illness onset, including physical injury and if resulted from domestic violence (physical abuse), sexual abuse, witnessing to accident, emotional abuse (or maltreatment), and whether or not fulfilling the criteria of PTSD.
- Pattern of parenting styles: using the Parenting Styles Questionnaire (PSQ) Arabic version [I].
The PSQ was designed to provide an inventory of parents’ perception concerning their behaviors and attitudes toward their children. It was tested for its validity and reliability, by applying a questionnaire on two different populations, under the same circumstances (50 parents of children at nursery schools) with 30-day interval, showed 0.90 results of Pearson’s correlation coefficient, indicating that scale of high validity and reliability and could be used at our research.
- Each parent was evaluated for his/her parenting style, using this instrument, which is composed of 70 self-report items. Each item was answered on a four-point scale, with scoring of one to four. These 70 questionnaire items address seven parenting (maternal and paternal) styles such as democratic, acceptance, authoritativeness, cruelty, rejection, overprotection, and negligence (Robinson etal., 1995).
Laboratory assessment: through withdrawal of blood samples as 3 ml (minimum 1.5 ml) through clean venous puncture from children of both groups (after written parents’ consent), for estimation of ‘anti-streptolysin O titer (ASOT).’ Blood samples were withdrawn using plastic-disposable syringe on plain tubes, by a well-trained nurse, with minimal pain and discomfort that might be occurred. All obtained blood specimens were collected and discarded in labs, than following infection-control measures.
A positive test usually is more than 200 U/ml, with repeated serial blood samples to all positive cases within a 2–4-week interval, to ensure positive results. A single rising titer of ASO was considered as a weak evidence, while either persistent or double-fold rise in ASOT was considered as a strong evidence for recent streptococcal infection.
Data management and statistical analysis
All data were recorded and statistical analysis was done using the package SPSS, version 20 (Statistical Package for Social Sciences, NC,USA,SAS institution) for Windows. Qualitative data were expressed as frequency (%).χ2 test was used for testing statistical significance of the relationship between different categorical variables. Fisher’s exact test (or Monte Carlo correction) was used if more than 20% of expected values were less than 5 or any cell contained an expected value less than 1. Spearman coefficient was used to study the correlation between two different quantitative variables.
Multiple logistic regression analysis was used to identify the predictors for OCD. Tablesand graphs were used as appropriate. Statistical significance was considered when Pvalue was less than 0.05.
All ethical considerations were considered, including:
- An informed consent was fulfilled by all children parents (father and mother for each child, including both groups ‘OCD and control’) before taking any data or doing any investigations (regarding withdrawal of blood sample), according to the rules of Research Ethics Committee of Suez Canal University.
- In case of illiterate patients, a witness was available.
- No financial compensation for the patients for time and effort was obtained.
| Results|| |
As shown in [Table 1], age and sex of both the studied groups were matched to each other, with a relatively higher distribution of the male sex among OCD children. On the other hand, distribution of age groups among OCD children was in ascending order. There was a statistically significant difference regarding the socioeconomic state, as most of the OCD groups were of middle and low socioeconomic standards respectively, while most of the control groups were of middle standard.
[Table 2] shows that the OCD group is statistically significantly different from healthy controls (P≤0.05), with 40% of the OCD group having a history of traumatic life events, particularly of emotional abuse, in comparison with only 2.5% of the control group.
|Table 2 Comparison between the two studied groups according to history of traumatic life events|
Click here to view
As shown in [Table 3], there were no statistically significant differences between both the studied groups, regarding either lifetime diagnosis of OCD among their parents, or family history of psychiatric disorders of their first-degree relatives.
|Table 3 Comparison between family history of psychiatric disorders of both the studied groups|
Click here to view
[Table 4] shows a statistically significant difference between fathers’ parenting styles of both the studied groups, as the authoritarian parenting style was the most distributed type among fathers of OCD children, with obtaining the highest scores on cruelty, and the lowest scores on acceptance as well as rejection, in comparison with the authoritative parenting style, among those of healthy controls, with obtaining the highest scores on acceptance, and the lowest scores on cruelty, regarding both global and scoring assessment, respectively.
|Table 4 Comparison between the two studied groups according to fathers’ parenting styles, using global assessment and scoring assessment|
Click here to view
[Table 5] shows a statistically significant difference between mothers’ parenting styles of both the studied groups, as the authoritarian parenting style was the most distributed type among mothers of OCD children, with obtaining the highest scores on authoritativeness as well as acceptance, and the lowest scores on negligence, in comparison with permissive (or indulgent) parenting style, among those of healthy controls, with obtaining the highest scores on acceptance, and the lowest scores on cruelty, regarding both global and scoring assessment, respectively.
|Table 5 Comparison between the two studied groups according to mothers’ parenting styles, using global assessment and scoring assessment|
Click here to view
[Table 6] shows a statistically significant difference of ASOT results among the OCD children, in comparison with controls, indicating higher incidence of recent group-A beta-hemolytic streptococcal infection among the OCS children (P≤0.05).
|Table 6 Comparison between the two studied groups according to anti-streptolysin O titer|
Click here to view
| Discussion|| |
Considering that OCD has a heterogeneous etiology, and the exact causes and underlying pathogenesis of the disorder are not well understood, the purpose of this study was to assess some risk factors in school-aged children suffering from OCD in comparison with age-matched and sex-matched healthy children, who were not suffering from any psychiatric symptoms or disorders.
The results of this study showed that the male sex was relatively predominant among the OCD group. It has been noted also that the OCD was more frequent among children aged from 10 to 12 years, while it was less frequent in children aged from 6 to 8 years. Previous epidemiological studies that studied the correlation between OCD and the socioeconomic status are contradictory and nonconclusive. The current study shows statistically significant distribution of OCD among children of middle and low socioeconomic state, respectively ([Table 1]). There were no statistically significant differences between the two studied groups regarding residence, whether being from urban or rural area. The present study could not find any statistically significant differences among the first-born children between both the studied groups ([Table 1]).
The result of the current study has shown statistically significant history of traumatic life events, that was reported among OCD children, in comparison with others of healthy control, with the majority of them having a history of emotional abuse ([Table 2]). This result strongly supports evidence of a unique relation between trauma exposure and OCD even in the absence of a formal PTSD diagnosis that comes in line with other several studies (Fontenelle et al., 2012; Kroska et al., 2018). Similarly, studies have found a significantly elevated rate of negative life events that were reported in one year prior to onset of OCD in children in an outpatient setting (Gothelf et al., 2004).
These findings came in agreement with a comparable study that has examined the relationship between childhood trauma and OCD in 938 students, using the LOI-CV. Between 13 and 30% of patients met the criteria for childhood trauma, with the most commonly reported experience that was the emotional neglect. There was a small but significant association between OCD and childhood trauma, particularly emotional abuse and physical neglect (Mathews et al., 2008).
In contrast to our expectations, there was no statistically significant difference in lifetime diagnosis of OCD and other psychiatric disorders, either between parents or the first-degree relatives, of both the studied groups ([Table 3]).
These findings became consistent with many studies that were researching for age-related changes in anxiety generally, and have shown moderate stability during childhood and reported an influence of shared environmental factors on emerging OCS, that fades as children enter adolescence (Hudziak et al., 2004; Van Grootheest et al., 2007; Lamb et al., 2010). It was suggested that possible gene–environment interactions include the effect of exposure to a traumatic event or environmental stress that may predispose to the risk of developing childhood OCD, rather than genetic factor alone (Walitza et al., 2008; Walitza et al., 2010). Thus, our results can be explained by the need of multiple risk factors for development of OCD.
Concerning parenting styles, the results of the present study showed a statistically significant difference between parenting styles of both the studied groups, as the authoritarian parenting style was the most prominent style among fathers of OCD children, with obtaining the highest scores on cruelty, in comparison with authoritative style, among those of healthy controls, with obtaining the highest scores on acceptance ([Table 4]).
On the other hand, the authoritarian parenting style was also the most prominent style among mothers of OCD children, with obtaining the highest scores on authoritativeness as well as acceptance, in comparison with permissive style, among those of healthy controls, with obtaining the highest scores on acceptance ([Table 5]).
In line with these findings, it was found in previous review that OCS was strongly associated with retrospective and observational studies of authoritarian parenting. Also, authoritative parenting, which includes both high levels of warmth and behavioral control, was negatively correlated with OCS. Analyses revealed that OCS was specifically linked only with authoritarian parenting after taking into account the other parenting styles and general mood and anxiety symptoms (Ballash et al., 2006).
Also, the results of the current study were in agreement with previous research that has hypothesized a central role of social learning as parent–child interactions, in the development of OCD, according to cognitive behavioral theories. The relationships between parenting styles, OCSs, and obsessive beliefs, were examined in a nonclinical sample (N=227). The results indicated that the authoritarian parenting style was significantly associated with both OCS and OC beliefs, even after controlling for general distress (Timpano et al., 2010).
Regarding ASOT, the results of the current study showed a statistically significant difference between ASOT of OCD children, in comparison with other healthy controls, indicating evidence of recent group-A beta-hemolytic streptococcal infection among the OCD children ([Table 6]).
In agreement with our results, the levels of ASOT in addition to other autoantibodies, were assessed in a large cohort study of 77 children and adolescents (59 males, 18 females, with the mean age at 6.3±2.5 and 14.5±2.0 years) of sudden onset or abrupt exacerbations of OCS and/or tics, to evaluate the prevalence of autoimmune phenomena in patients with PANDAS. On comparison with those of age-matched and sex-matched healthy controls, there were significantly higher ASOT and anti-DNAseB titers, as well as a history of more frequent throat infections than controls among PANDAS patients (Stagi et al., 2014).
A previous study was conducted among 40 adult OCD patients, subdivided into 18 of early onset and 22 of late onset, in comparison with 14 controls of psychiatric patients. It was found that childhood-onset OCD was associated with higher mean ASOT, higher frequencies of tic disorders, and tonsillitis, without any differences in other autoimmune parameters. This can explain the role of autoimmunity in the pathogenesis of some forms of childhood-onset OCD, as in PANDAS (Morer et al., 2006).
Furthermore, it is important to mention that a persistent elevated ASOT will add support, but not provide proof that OCD resulted from a streptococcal infection, which is very common in the school-age children. On the other hand, neither high nor low blood level of ASOT alone could confirm or rule out PANDAS, and further exploration of markers other than ASOT is needed.
| Conclusion|| |
This study concluded the following:
- Authoritarian parenting style as well as cruelty and authoritativeness, even in the presence of acceptance, were established as the most risk factors or predictors for developing childhood OCD, together with trauma exposure, particularly that of emotional abuse (either of maltreatment or neglect) even in the absence of a formal PTSD diagnosis.
- The role of post-streptococcal infection in OCD pathogenesis could not be excluded, as it was identified as a risk factor for the development of OCD in school-age children, although we could not provide a definite evidence.
Limitations of the study
- The foremost and obvious limitation of this study is that it was conducted on a small sample size and in one geographical area. Consequently, the participants might not be representative of the general population, which have consequences in reducing statistical power and capacity to generalize our research’s findings.
- The measurements used in this study consisted of self-report questionnaires, most questions were descriptively oriented, and some scores might be a result of faulty observations and/or interpretations of children and their parents. One could argue that these measures lack accuracy and validity.
- PSQ was filled out from parents or even caregivers, who have been assumed the absent role (whether died, divorced, traveling away, or arrested in prison), not sticky to the parent himself, which did not allow for reliable comparisons, and impair the validity of the obtained information.
- Conducting more extensive, larger, longitudinal studies that will strengthen the statistical significance of our study’s results with further monitoring of progression of these symptoms from childhood to adulthood.
- Future research should investigate additional risk and protective factors of OCD. Beyond this, risk factors could be examined in relation to the specific symptom dimensions such as checking, contamination/washing, …, etc. On the other hand, protective factors may include social support and religious involvement.
- Preventive strategies should focus on positive parenting and nonviolent caregiving measures, as well as psychoeducation programs on optimal parenting styles with early establishment of effective practices, which are supposed to be important for the child’s social and emotional growth adjustment.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
American Academy of Child and Adolescent Psychiatry (AACAP), (2012). Practice parameters for the assessment and treatment of children and adolescents with obsessive compulsive disorder. J Am Acad Child Adolesc Psychiatry 51:98–113.
American Psychiatric Association, (2013). Diagnostic and Statistical Manual of Mental Disorders.: DSM-5 (5thed)
. Washington, DC: American Psychiatric Association; pp. 237–242.
Ballash N, Leyfer O, Buckley AF, Woodruff-Borden J (2006). Parental control in the etiology of anxiety. Clin Child Fam Psychol Rev 9:113–133.
Barnhart C, Raval V, Jansari A, Raval P (2013). Perceptions of parenting style among college students in India and the United States. J Child Fam Stud 22:684–693.
Brander G, Perez-Vigil A, Larsson H, Mataix-Cols D (2016). Systematic review of environmental risk factors for obsessive-compulsive disorder: a proposed roadmap from association to causation. Neurosci Biobehav Rev 65:36–62.
De Mathis MA, Diniz JB, Hounie AG, Shavitt RG, Fossaluza V, Ferrão Y (2013). Trajectory in obsessive-compulsive disorder comorbidities. Eur Neuropsychopharmacol 23:594–601.
Fontenelle LF, Cocchi L, Harrison BJ, Shavitt RG, do Rosário MC, Ferrão YA et al.
(2012). Towards a post-traumatic subtype of obsessive-compulsive disorder. J Anxiety Disord 26:377–383.
Geller DA (2010). Obsessive-compulsive disorder. In: Dulcan MK, editor. Textbook of child and adolescent psychiatry
. Washington, DC: American Psychiatric Publishing Inc; pp. 349–363.
Gothelf D, Aharonovsky O, Horesh N, Carty T, Apter A (2004). Life events and personality factors in children and adolescents with obsessive-compulsive disorder and other anxiety disorders. Compr Psychiatry 45:192–198.
Hudziak James J, Van Beijsterveldt CEM, Althoff Robert R, Stanger C, Rettew David C, Nelson Elliot C et al.
(2004). Genetic and environmental contributions to the child behavior checklist obsessive-compulsive scale: a cross-cultural twin study. Arch Gen Psychiatry 61:608–616.
Kroska EB, Miller ML, Roche AI, Kroska SK, O’Hara MW (2018). Effects of traumatic experiences on obsessive-compulsive and internalizing symptoms: the role of avoidance and mindfulness. J Affect Disord 225:326–336.
Lamb DJ, Middeldorp CM, Van Beijsterveldt CEM, Bartels M, Polderman TC, Boomsma DI (2010). Heritability of anxious-depressive and withdrawn behavior: age-related changes during adolescence. J Am Acad Child Adolesc Psychiatry 49:248–255.
Martino D, Defazio G, Giovannoni G (2009). The PANDAS subgroup of tic disorders and childhood-onset obsessive-co mpulsive disorder. J Psychosom Res 67:547–557.
Matejevic M, Todorovic J, Jovanovic AD (2014). Patterns of family functioning and dimensions of parenting style. Proc Soc Behav Sci 141:431–437.
Mathews CA, Kaur N, Stein MB (2008). Childhood trauma and obsessive-compulsive symptoms. Depress Anxiety 25:742–751.
McCullough CA (2011). Social learning theory and behavioral therapy: Considering human behaviors within the social and cultural context of individuals and families. Soc Work Public Health 26:471–481.
Morer A, Vinas O, Lazaro L, Calvo R, Andres S (2006). Subtyping obsessive–compulsive disorder: clinical and immunological findings in child and adult onset. J Psychiatr Res 40:207–213.
Nestadt G, Samuels J, Riddle M, Bienvenu OJ3rd, Liang KY, LaBuda M et al.
(2000). A family study of obsessive compulsive disorder. Arch Gen Psychiatry 57:358–363.
Rady A, Salama H, Wagdy M, Ketat A (2013). Obsessive compulsive phenomenology in a sample of Egyptian adolescent population. Eur J Psychiatry 27:89–96.
Real E, Labad J, Alonso P (2011). Stressful life events at onset of obsessive-compulsive disorder are associated with a distinct clinical pattern. Depress Anxiety 28:367–376.
Robinson C, Mandleco B, Olsen SF, Hart CH (1995). Authoritative, authoritarian, and permissive parenting practices: development of a new measure. Psychol Rep 77:819–830.
Ruscio AM, Stein DJ, Chiu WT, Kessler RC (2010). The epidemiology of obsessive compulsive disorder in the national comorbidity survey replication. Mol Psychiatry 15:53–63.
Snider LA, Swedo SE (2003). Childhood-onset obsessive-compulsive disorder and tic disorders: case report and literature review. J Child Adolesc Psychopharmacol 13 (Supplement 1):S81–S88.
Stagi S, Rigante D, Lepri G, Bertini F (2014). Evaluation of autoimmune phenomena in patients with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Autoimmun Rev 13:1236–1240.
Teixeira AL, Rodrigues DH, Marques AH, Miguel EC, Fontenelle LF (2014). Searching for the immune basis of obsessive-compulsive disorder. Neuroimmunomodulation 21:152–158.
Timpano KR, Keough ME, Brittain Mahaffey MS, Schmidt NB, Abramowitz J (2010). Parenting and obsessive compulsive symptoms: implications of authoritarian parenting. J Cogn Psychother 24:151–164.
Van Grootheest DS, Bartels M, Cath DC, Beekman AT, Hudziak JJ, Boosma DI (2007). Genetic and environmental contributions underlying stability in childhood obsessive-compulsive behavior. Biol Psychiatry 61:308–315.
Vasey MW, Dadds MR (2001). An introduction to the developmental psycho-pathology of anxiety
. New York: Oxford University Press; pp. 3–26.
Walitza S, Scherag A, Renner TJ, Hinney A, Remschmidt H, Herpertz-Dahlmann B et al.
(2008). Transmission disequilibrium studies in early onset of obsessive–compulsive disorder for polymorphisms in genes of the dopaminergic system. J Neural Transm 115:1071–1078.
Walitza S, Wendland JR, Gruenblatt E, Warnke A, Sontag TA, Tucha O et al.
(2010). Genetics of early-onset obsessive-compulsive disorder. Eur Child Adolesc Psychiatry 19:227–235.
Zohar AH, Felz L (2001). Ritualistic behavior in young children. J Abnorm Child Psychol 29:121–128.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]