ORIGINAL ARTICLE

Year : 2013  |  Volume : 34  |  Issue : 2  |  Page : 98-103

Central auditory processing and audio-vocal psycholinguistic abilities in children with attention deficit-hyperactivity disorder

Asmaa Abdel-Hamid¹, Rasha Safwat¹, Omnia Raafat², Hani Hamed³, AyaAllah Farouk^4
1 Department of Phoniatric, Kasr El Aini Hospital, Cairo University, Cairo, Egypt
² Department of Psychiatry, Kasr El Aini Hospital, Cairo University, Cairo, Egypt
³ Department of Psychiatry, Beni Suef University, Beni Suef, Egypt
⁴ Department of Neurophysiology, Kasr El Aini Hospital, Cairo University, Cairo, Egypt

Correspondence Address:
Omnia Raafat
MD, Department of Psychiatry, Kasr El Aini Hospital, Cairo University, 9 Saied Zo El-Fakar Street, Manial El-Roda, Cairo
Egypt

Source of Support: None, Conflict of Interest: None

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DOI: 10.7123/01.EJP.0000422007.47886.8b

Objective

Central auditory processing disorders and attention deficit-hyperactivity disorders (ADHD) have become popular diagnostic entities for school-age children. P300 (P3) event-related potential (ERP) putatively reflects central auditory dysfunctions associated with ADHD.

Forty children with a diagnosis of ADHD according to Diagnostic and Statistical Manual of Mental Disorders, 4th ed. and 39 normal children were included in the study and were subjected to P300 ERP, audio-vocal items of Illinois test of psycholinguistic abilities.

This study found a significant difference in P300 latency, amplitude, and most of the audio-vocal subtests between the patients and the controls. This difference was obvious in older children for the Illinois test, but was not observed in P300 results.

There was a CAPD in ADHD children as indicated by decreased amplitude of P300 and prolonged latency in such children.

Keywords: attention deficit-hyperactivity disorder, auditory P300, psycholinguistic abilities

Introduction

Participants and methods

1. Inclusion criteria
   1. Average and below average IQ.
2. Exclusion criteria
   1. No history of delayed language development.
   2. No history of hearing or neurological disorders.

1. Psychiatric assessment: Semistructured psychiatric interview with the child and his/her parents for history taking including personal, prenatal, natal, and postnatal, developmental history, history of childhood illness, and social behavior of the child. A mental status examination was also carried out to confirm that the patients had the diagnosis of ADHD according to the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) diagnostic criteria (American Psychiatric Association, 1994).
2. General and neurological examination.
3. Psychometric assessment:
   1. The Stanford Binet Intelligence Test is a standardized test that assesses IQ and cognitive abilities in children and adults. This was done to exclude borderline IQ and mental retardation (Terman and Merrill, 1960).
   2. Conners’ Parent Rating Scale-Revised, long version (CPRS-R: L), was used to assess the severity of symptoms as reported by parents. This form includes 80 items grouped into different subscales. The CPRS-R: L in the Arabic language was developed by translation and back translation with the permission of the original author (Conners, 2001).

After confirmation of the psychiatric assessment and diagnosis, patients and control children were sent to the Phoniatric Clinic and subjected to the following:

1. Ear, nose, and throat examination, and language assessment to exclude language delay.
2. The Illinois Test of Psycholinguistic Abilities (ITPA) Arabic edition (2–10 years) (El-Sadi et al., 1998). In this study, only the audio-vocal items are studied, which include auditory reception, auditory association, verbal expression, grammatical closure, auditory sequential memory, auditory closure, and sound blending (Appendix 1). [Additional file 1]

Then the patients (medicated and nonmedicated) and control children were sent to the neurophysiology department for the assessment of ERP (P300): A double-blind study was carried out as the clinician in the Neurophysiology Department was not aware of whether or not the patients were taking methylphenidate. The medicated children received a dose of 10 mg of methylphenidate 60 min before P300. P300 was determined using head phone TDH 39. An odd-ball paradigm was used, where the participant was instructed to react to occurrences of a tone (target) presented during 20% of trials and to ignore a frequent tone present on other trials. P300 responses were obtained in response to the target stimuli. P300 amplitude is the difference in microvolt between the point of maximum amplitude of the designated peak and the stimulus baseline. P300 latency was measured from the time of stimulus onset to the point of maximum amplitude of the chosen peak.

Statistical analysis



Data are represented as mean±SD. Data of the patients and the controls were compared using an independent t-test. According to Conners’ T-subscales, patient data were divided into three groups: group 1 (T⩽65); group 2 (T=66–70); and group 3 (T>70), where the number, validity, and cumulative percent were determined. The Pearson correlation coefficient test was used to correlate patients’ Conner T-subscales with patients’ P300 and Illinois subsets. Two-tailed significant values were considered when P value was less than 0.05. Data were analyzed using SPSS for windows, version 11 (IBM, Chicago, Illinois, USA) (Barry et al., 2003).

Results

The mean chronological age of the patient group was 8.1±1.64 years and the mean chronological age of the control group was 8.23±1.38 years (P=0.72). The patient group included 32 (80%) boys and 8 (20%) girls and the control group included 30 (77%) boys and 9 (23%) girls, with a nonsignificant difference (P=0.69). There was a statistically significant difference between ADHD children and the controls in P300 amplitude and latency (P⩽0.001 and 0.002, respectively) [Table 1].

Table 1: P300 in children with attention deficit-hyperactivity disorders and controls Click here to view

There were statistically significant differences in auditory reception (P=0.006), auditory association, auditory sequential memory, sound blending, and auditory closure (P⩽0.001) between the cases and the controls [Table 2].

Table 2: Performance of children with attention deficit-hyperactivity disorders and controls on Illinois subtests Click here to view

There was a negative significant correlation between P300 latency and the auditory sequential memory (P=0.013) [Table 3].

Table 3: Correlates of P300 with Illinois subtests Click here to view

The following are Conners’ subscales: (A) Oppositional, (B) Cognitive Problems/Inattention, (C) Hyperactivity, (D) Anxious-Shy, (H) ADHD Index, (E) Perfectionism, (F) Social Problems, (G) Psychosomatic, (I) Conners’ Global Index Restless-Impulsive, (J) Conners’ Global Index Emotional lability, (K) Conners’ Global Index Total, (L) DSM-IV Symptoms inattentive, (M) DSM-IV Symptoms Hyperactive-Impulsive, and (N) DSM-IV Symptoms Total. There was a positive correlation between inattention and hyperactivity with P300 latency. Also, there was a negative correlation between Conners’ Global Index Restless-Impulsive (I) and both auditory reception and auditory sequential memory [Table 4].

Table 4: Correlation between Connors’ subscales, P300, and Illinois subtest Click here to view

There were highly significant differences in auditory reception, auditory association, verbal expression, grammatic closure, auditory sequential memory, and sound blending. This indicates that older children had more impairment than younger children [Table 5].

Table 5: Age differences among the studied patients in the P300 and Illinois subtests Click here to view

There was a longer P300 latency in nonmedicated children than the medicated children, with a significant difference (P<0.001) [Table 6].

Table 6: Effect of medication (methylphenidate) on P300 and Illinois subtsets in the patient group (n=40) Click here to view

Discussion

We carried out this study to detect higher auditory function disorder (CAPD) in ADHD children through P300 and the Illinois subtest. ERPs reflect their perceived importance as possibly providing clues to ADHD’s underlying pathophysiology; brain-related processes reflecting deficits in inhibitory control have received particular attention in ADHD research (Hinshaw, 2003; Abdel Hamid et al., 2010). P300 amplitude is believed to provide a psychophysiological signature of these deficits (Barry et al., 2003). The results indicated longer latency and smaller amplitude in ADHD children as compared with their controls [Table 1]. Our findings might indicate that the children with ADHD showed signs of late-stage auditory perceptual processing. In agreement with our findings, Satterfield et al. (1994) have suggested the existence of abnormal sensory and cognitive information processing in patients with ADHD. They have reported lower amplitudes of the P300 wave, which is related to problems with signal recognition and transduction. A possible explanation was provided by Hoeksma et al. (2006), who reported that an abnormally small P300 amplitude is an indication of abnormal functioning of neuronal generators (temporal, parietal, and frontal areas), as these neuronal generators need to be intact for the P300 to attain normal levels. Another explanation was provided by Barry et al. (2003), who found that the P300 component is partly associated with frontal function, and the most accepted interpretation is that it relates to the involvement of executive and attentional resources. In agreement with our findings, a small P300 amplitude in ADHD children is in agreement with the findings of Van der Stelt et al. (2001), but others have reported that they are equivalent (Rothenberger et al., 2000). In the present study, the delayed latency might indicate that more time was required to complete stimulus evaluation in the auditory modality at the higher processing level. Jonkman et al. (1997) reported significantly longer latencies in ADHD children, which is in agreement with our results. In terms of the audio-vocal subtests of Illinois, there was a highly significant difference between cases and controls in the studied items, except in verbal expression and grammatical closure [Table 2]. In the present study, auditory reception was impaired in the ADHD=children. We observed that the children did not recognize or identify sounds in their environment, did not have listening attitude, were not able to attach meaning to words, and were also not able to follow consecutive speech. This can be attributed to defective attention in these children. Auditory association was also significantly impaired in ADHD children in comparison with the controls. It was found that the children had difficulty holding more than one concept in mind and consider the relation between them. This finding can be attributed to the short-term memory defects in these children. Barkley (2003) has reported that children with ADHD cannot hold a concept as well as the semantic representation of the auditory stimulus applied to them and recall other concepts related to it. Auditory sequential memory was impaired in children with ADHD in comparison with the controls. These results can be attributed to memory deficit in ADHD children. Auditory sequential memory is considered a complex item of Illinois test that is a processing-based problem; thus, its defect might indicate CAPD. Several studies have reported memory deficiencies in children diagnosed with attention problems (Brocki et al., 2008; Shaheen et al., 2011). Martinussen et al. (1987) have found that working memory, both verbal and spatial, was impaired in ADHD children. Gomarus et al. (2009) have reported that the Central Executive of working memory was impaired in ADHD children. Auditory closure was also defective in ADHD children compared with the control group. In the current study, it was observed that the child had to listen hard sometimes to be aware that part of the word is missing. Yet for some children, it was observed that the word could be unrecognizably changed. Auditory closure and sound blending defects are because of the presence of defects in the phonological storage and recall of the articulatory loop of words, especially the newly acquired ones (Shaheen et al., 2011). As such, phonological short-term memory is integrally involved in the development and acquisition of academic skills. Shibasaki and Miyazaki (1992) have found that a defect in these abilities may also be attributed to defective central auditory processing because of the concern that ADHD may be frequently comorbid with, or even indistinguishable from, CAPD, which may impact on the child’s educational achievements. Grammatic closure and verbal expression values showed a nonsignificant difference between patients and controls. This can be explained by the selection of the patients; their main complaint was poor academic achievement, with no language problem[25]. In the present study, there was also positive correlation between P300 latency and inattention and hyperactivity subscales of Conners’ Parents Rating Scale. This can be attributed to the fact that the child cannot sit still as there is increased distractibility in children with ADHD; thus, the stimulus takes a longer time to be processed. There was a negative correlation of auditory sequential memory and P300 latency, which can be attributed to the longer time required for the stimulus to be processed (Booth et al., 2005). In terms of the age difference in the results of this study [Table 5], it was found that there was no difference in P300 results in the two age groups, despite the presence of a highly significant difference in the results of Illinois tests. This result was not in agreement with the findings of Shibasaki and Miyazaki (1992) of a decrease in latency and an increase in amplitude with age. In our study, a significant difference between the two age groups in the Illinois subtest scores with considerably impaired abilities in older children might reflect their poor academic achievement. The results of the present study on the effect of medication on amplitude and latency indicated that nonmedicated ADHD children had longer P300 latencies than children medicated with methylphenidate. Some studies have reported an increase of the P300 amplitude with stimulant medication in ADHD (Seifert et al., 2003). However, there is still controversy in terms of their effect on the P300 latency. However, Schochat et al. (2002) have pointed that methylphenidate did not have a significant effect on any of the central auditory processing measures, although it was found that their performance improved significantly on the attention/impulsivity test. It should be noted that an improvement in the child’s attentive ability facilitates the evaluation of AP, with less stress on the child.

Conclusion and recommendations

There was a CAPD in children with ADHD (as indicated by Illinois subtests) and higher auditory central cognitive function (indicated by decreased amplitude of P300 and prolonged latency in such children). Audio-vocal abilities are more defective in older children (8–10 years) than in younger children. Children with ADHD should be assessed for CAPD and a rehabilitation program for their deficits should be implemented. Stimulants may decrease the P300 latency and hence improve the attentive ability and auditory process.

 

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Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]

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