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Brief Reports Indian Pediatrics 2000;37: 1256-1260. |
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Spectrum
of Attention Deficit Hyperactivity Disorders in Children Among |
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Attention deficit hyperactivity disorder (ADHD) is one of the most frequently diagnosed psychiatric disorder in children. The cardinal symptoms of the disorder include inappropriate levels of inattentiveness, motor over activity and impulsivity. In order to meet established criteria for diagnosis it is important that the symptoms must appear in at least two contexts, for a duration of at least 6 months, have an onset before age 7 and cause signifi-cant functional impairment(1). Estimates vary widely with some studies reporting 10-20% of prevalance among school aged children and others more conservatively reporting 1-2%(2,3). Boys outnumber girls by a large margin (9:1) in clinical samples but by a smaller ratio (3:1) in the community(4,5). Despite considerable research, ADHD remains one of the most difficult diagnosis to categorize as evidenced by frequent changes in the diagnostic criteria in the various editions of the DSM. In the latest edition, the DSM IV lists the 3 cardinal symptoms into two core dimensions, inattention and hyperactivity/impulsivity and recognizes three sub types(1). Sub types are defined by whether a child meets the threshold criteria of 6 symptoms for inattention only, the predominantly inattentive type (ADHD-AD), 6 symptoms for hyper-activity/impulsivity only, the predominantly hyperactive/impulsive type (ADHD-HI), or 6 symptoms from both the dimensions, the combined type (ADHD-CT). In India there is very little systematic research in ADHD in children(6). The few studies that are available report prevalence rates ranging from 10 to 20%(7,8). The present study aimed at (i) determining the prevalence of ADHD among children (3-12 years) attending psychology outpatient services in the Department of Pediatrics of a tertiary care hospital using the DSM-IV criteria, and (ii) examining the relationship of the three sub types of ADHD with academic, behavior and peer difficulties.
All children referred for evaluation to the Psychology Outpatient services of the Department of Pediatrics of a tertiary care teaching hospital from January 1998 to March 1999 were screened for ADHD. Children meeting the clinical criteria of ADHD as per the DSM IV criteria were subjected to detailed physical, neurological and mental status examination. In order to study the prevalence of ADHD in a neurologically normal population all children with epilepsy, autism, mental retardation, sensory deficits or brain damage were excluded. Three children were thus excluded. Moreover, children who did not come for completion of their assessments (e.g., intelligence testing) were excluded (n = 2). The intelligence of the children was measured by the Indian adaptation of the Wechsler Intelligence Scale for Children(9) and for children below 6 years, the academic sub test of the Developmental Profile II(10) was used to calculate the equivalent IQ score as per the guidelines. The Indian adaptation of the Vineland Social Maturity Scale(11) was used to calculate social quotients (SQ) as a measure of adaptive behavior functioning. In addition, all parents completed the Conners Parent Rating Scale(12) and school teachers completed the Conners Teacher Rating Scale(13). Children meeting the criteria for ADHD were also assessed for co-morbid conditions using the DSM IV criteria.
Out of the 245 children (after excluding 5 cases) referred for psychosocial evaluation in the outpatient psychology clinic from January 1998 to March 1999, 20 children (8.1%) were found to meet the DSM IV criteria for ADHD. Majority of the children were referred for poor school performance (40%) and an additional 30% for behavioral problems and intelligence testing, and the rest (30%) for hyperactivity. The male : female ratio of all children attending the psychology outpatient services was 2.6 : 1, whereas the M : F ratio in children with ADHD was 5 : 1. The mean age of the children with ADHD was 6 years and 8 months and the Mean IQ was 85 with a range of 72 to 109. On the basis of the number of behavioral symptoms endorsed in the two domains of inattention and hyperactivity/impulsivity, the children were categorized into 3 sub types. Fifty per cent were diagnosed to be primarily hyperactive-impulsive type, 35% were primarily inattentive type and 15% were combined type. Forty per cent of the children with ADHD had a comorbid disorder. Four children with ADHD had a comorbid specific learning disorder, 3 met the clinical criteria for oppositional defiant disorder, and 1 child had a comorbid Tourette disorder. The three sub types of ADHD were found to differ on several characteristics (Table I). The ADHD-HI type was the youngest group and was on an average three years younger than the ADHD-AD group and four years younger than the ADHD-CT group. The three sub types also differed on intelligence, with ADHD-HI having lower IQ (M = 81) as compared to the ADHD-CT (M = 89) and the ADHD-AD (M = 90). However, the three sub types did not differ on their adaptive behavior functioning as measured by the VSMS. Table I__Characteristics of Children with ADHD by Type
Besides comorbidity, children with ADHD had behavior, academic and peer problems. Sixty per cent of the children with ADHD were reported to have academic difficulties as measured by failing in one or more school subjects, inability to cope with school work, or getting bare passing grades. In addition, 20% had repeated a class. Although, the three sub types did not differ on the proportion reported to having academic difficulties, a higher proportion of ADHD-AD had repeated a grade (43%) as compared to the ADHD-HI (10%) and ADHD-CT (0%). Sixty per cent of the ADHD children were reported to manifest behavioral problems as reported by parents and teachers on the Conners Parent and Teacher Forms including non-compliance, aggressiveness, destructive-ness, temper tantrums, bed wetting, thumb sucking, nail biting, lying and stealing. A higher percentage of the ADHD-CT (100%) had problem behaviors, while 70% of the ADHD-HI and 29% of the ADHD-AD had behavior problems. Peer difficulties were reported for three-fourth of the children with ADHD. Peer problems as reported by school teachers on the Conners Teacher Report Form ranged from not being liked by the classmates, being rejected, being unacceptable to the group, and not having a single good friend. Friendship difficulties were more marked for the ADHD-CT group and the ADHD-HI group.
The prevalence of ADHD among children aged 3-12 years attending Psychology Outpatient services in the Department of Pediatrics was 8.1%. Epidemiological studies reveal prevalence rates ranging widely from 1% to 23% depending upon the definition used and the population sampled(2,3). Prevalence estimates based on a behavioral definition which assesses symptoms shown at a single point of time is found in 10-20% of general population in India(7) and the west(14). Prevalence estimates based on a psychiatric definition according to the DSM criteria, with specific inclusion criteria, onset of symptoms, pervasiveness, duration and impairment, is found in 5 to 10% of the general population, while this prevalence declined to 1-2% in the studies using the ICD criteria for hyper-activity(2). The male-female ratio of children with ADHD was 5 : 1. Several studies have docu-mented greater incidence of the disorder among boys than in girls both in the western countries(5) and in India(7). The age at referral for the ADHD-HI was the lowest, while the age at referral for the ADHD-AD type was higher. A possible explanation for this finding is that younger children who qualify for the predominantly ADHD-HI type do not exhibit levels of inattention because they are in preschool and have not yet faced demands on their attentional capacity which is required in higher classes and becomes evident at older ages. It is therefore possible that as the ADHD-HI children become older they may also show maladaptive levels of inattention so that they may change their sub type to that of ADHD-CT type. However, this can only be ascertained from a longitudinal perspective. The earlier age at referral of ADHD-HI type has been reported previously(15). In the DSM IV field trials, only one fourth of the children who met the criteria for the ADHD-HI type were older than 6 years as compared to 70% of children who met the criterion for the ADHD-AD or the ADHD-CT type(16). In our sample, poor academic performance as measured by percentage repeating a grade was the most prevalent problem of the ADHD-AD group with 43% having repeated a class. However, only 29% had behavioral problems and 43% had peer problems. These findings are consistent with previous findings of lower rates of behavioral problems and higher rates of academic difficulties in children with ADHD-AD(5,14). On the other hand, ADHD-HI was associated more with peer problems and behavioral difficulties rather than academic problems, despite relatively lower average IQ of this sub type as compared to the other two sub types. Among the ADHD-HI group only 50% were reported to have academic problems while 70% were reported to have behavior problems while 90% had peer difficulties. The relatively lower rates of academic problems is probably an artifact of the young age of children in this group. Since most ADHD-HI children were in pre-school, academic difficulties may not be very evident at this young age. Consistent with the results of other studies(5,15), the ADHD-CT group, the sub type which manifests symptoms of both inattention and hyperactivity/impulsivity, was the most impaired group. All the children were reported to have behavioral problems and peer problems and two-third were reported to have academic difficulties. Paternite et al.(16) found that children who meet the clinical criteria for the combined type had more behavioral problems at home, had less organized academic work and received more mental health services than clinic referred controls. We conclude that ADHD is one of the highly prevalent psychiatric disorders in childhood and is associated with clinically significant impairment in functioning. In order to successfully design an intervention program it is important that all the areas of impairment in children with ADHD be identified. Contributors: PM designed the study, collected the data, and drafted the paper. She will act as the guarantor for the paper. PS co-ordinated the study and also helped in drafting the paper. Funding:
None.
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