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PubMed2006

The impact of sex and subtypes on cognitive and psychosocial aspects of ADHD.

We compared the effect of sex and attention-deficit-hyperactivity disorder (ADHD) subtyping in groups of females and males. One hundred and one females with ADHD (mean age 10y 4mo [SD 2y 8mo]; range 5y-18y) were classified according to subtype by Diagnostic and Statistical Manual of Mental Disorders (4th edn) criteria (inattentive [ADHD-I]; combined [ADHD-C]) and balanced by subtype to 101 males (mean age 10y 5mo [SD 2y 9mo]; range 5y 4mo-17y 6mo). All children underwent IQ and reading assessment, and 109 underwent the continuous performance task (Test Of Variables of Attention [TOVA]). Parents completed the Conners' Abbreviated Rating Scale (ABRS), the Child Behavior Checklist (CBCL), learning disability questionnaires, and reported use and efficacy of methylphenidate. Teachers completed the Swanson, Kotkin, Agler, M-Flynn, and Pelham (SKAMP) rating scale. Sex differences were found only on the CBCL; females were more impaired on the attention (p<0.001) and somatization (p=0.028) subscales but not for IQ, other questionnaires, TOVA scores, methylphenidate treatment, or demographics. Females with ADHD-C, but not males, had significantly higher T-scores than females with ADHD-I on social, attention, delinquent, and aggressive behaviours. Regardless of sex, children with ADHD-C had higher scores on all CBCL subscales (p=0.047), ABRS (p<0.001), and SKAMP (p=0.03) than children with ADHD-I. The results support the supposition that ADHD in females is the same disorder as in males. ADHD subtyping was the important determinant of ADHD core symptoms; females with ADHD were found to have significant risk of psychopathology.

Adolescent↗

PubMed1989

Behavioral and cognitive subtypes of ADHD.

Attention-deficit hyperactivity symptoms are observed by teachers in 9.2% of a nonreferred elementary school population. Two subtypes of attention-deficit hyperactivity disorder (ADHD), a cognitive form and a behavioral form, are identified. The behavioral subtype includes about 80% of those identified and is characterized by distinct clinical phenomenology of inattention, impulsivity, and hyperactivity. These children can be described on a continuum of severity, with the most severe showing behavioral features indistinguishable from conduct disorder. Children with behavioral subtypes of ADHD do not exhibit the specific skill deficits on neuropsychological tests that are characteristic of reading disabled children. There is a second, less prevalent type of cognitive attention-deficit hyperactivity disorder constituting approximately 20% of ADHD children that includes severe academic underachievement along with inattention, impulsivity, and overactivity. Children with the cognitive subtype exhibit information processing deficits that involve inadequate encoding and retrieval of linguistic information, characteristic of reading disabilities.

Adolescent↗

PubMed2005

[The neuropsychological phenotype of attention deficit hyperactivity disorder: are there differences among subtypes?].

INTRODUCTION: Recent studies suggest that the ADHD subtypes would be best conceptualized as separate clinical entities, based on their epidemiology, central and associate symptomatology. OBJECTIVES: To determine the differences and similarities between subtypes in its associate symptomatology, specifically in the neuropsychological phenotype of executive dysfunction. PATIENTS AND METHODS: A group of children between 6 and 14 years of age with a diagnosis of ADHD-innattentive subtype (DESAT, n = 20) and another with ADHD-combined subtype (COMB, n = 39). RESULTS: Overall, the COMB subject sample displayed lower performance than DESAT group. Statistically significant differences were found in Kaufman-ABC-hands movement subtest, Wisconsin Card Sorting Test (WCST)-total error and WCST-conceptual level. CONCLUSIONS: The subtypes differ significantly in measures or non verbal working memory, hindsight, foresight, and motor control. Both groups share a deficit in response output speed and verbal working memory. We hypothesized areas of cognitive superiority for each subtype: spatial memory for the inattentive and gestaltic composition for the combined. Results provide evidence to support quantitative and qualitative differences in the neuropsychological profile between the ADHD-innatentive and combined subtypes.

Attention Deficit Disorder with Hyperactivity↗

PubMed2004

The impact of specific language impairment on working memory in children with ADHD combined subtype.

The objective of this study was to examine the impact of comorbid specific language impairment (SLI) on verbal and spatial working memory in children with DSM-IV combined subtype Attention Deficit Hyperactivity Disorder (ADHD-C). Participants were a clinical sample of 812- to 1212-year-old children diagnosed with ADHD-C. A group of ADHD-C with SLI was compared to a group of ADHD-C without SLI, and a group of normal children, matched on age and nonverbal intelligence. The results show that ADHD-C children with SLI scored significantly lower than those without SLI and normal children, on verbal working memory measures only. Both ADHD groups performed normally on spatial working memory measures. It is concluded that working memory deficits are not a specific characteristic of ADHD but are associated with language impairments. The importance of screening for language disorders in studies of neuropsychological functioning in children with ADHD is emphasized.

Adolescent↗

PubMed1999

Motor coordination and kinaesthesis in boys with attention deficit-hyperactivity disorder.

In the current study, movement ability and underlying kinaesthetic processes of boys with attention deficit-hyperactivity disorder (ADHD) were compared with a group of control children. Two groups of 16 boys with either predominantly inattentive subtype ADHD (ADHD-PI) or combined subtype ADHD (ADHD-C) were compared with 16 control boys matched on age and verbal IQ. The findings demonstrated that the children with ADHD had significantly poorer movement ability than the control children. A high percentage of children with ADHD displayed movement difficulties consistent with developmental coordination disorder. In addition, the current study found that the type and degree of movement difficulty differed between subtypes. Children with ADHD-PI had significantly poorer fine motor skill while children with ADHD-C were found to experience significantly greater difficulty with gross motor skill. The severity of the children's inattentive symptomatology was found to be a significant predictor of motor coordination difficulties. Kinaesthetic sensitivity was not found to differ significantly between the groups.

Attention Deficit Disorder with Hyperactivity↗

PubMed2000

Familial clustering of symptoms and disruptive behaviors in multiplex families with attention-deficit/hyperactivity disorder.

OBJECTIVE: To examine familial clustering of attention-deficit/hyperactivity disorder (ADHD), ADHD subtypes, symptoms, and oppositional behaviors in affected sibling pairs (ASPs) and their parents. METHOD: One hundred thirty-two ASPs, ranging in age from 5 to 25 years and ascertained through clinic and volunteer referrals, were examined for DSM-IV ADHD subtypes, oppositional defiant disorder (ODD), and conduct disorder (CD) with the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime version (K-SADS-PL). Two hundred fifty-six parents in these families were assessed by means of the SADS-Lifetime version, Modified for the Study of Anxiety Disorders, Updated for DSM-IV (SADS-LA-IV), and the Behavioral Disorders supplement of the K-SADS-PL to determine ADHD, ODD, and CD. RESULTS: Fifty-five percent of families ascertained through an ASP have at least one parent with a lifetime diagnosis of ADHD. The frequency of ADHD in at least one parent was higher in families with at least one affected girl (63%) than in families with only affected boys (45%) (p = .02). There was no evidence that affected siblings or parents within ASP families showed similar patterns of ADHD symptoms, such as ADHD subtype classification. In contrast, CD significantly clustered in ASP families. CONCLUSIONS: The sex difference in prevalence of ADHD among ASPs is consistent with a model of inheritance in which girls require a greater loading of familial influences to develop ADHD. The lack of familial clustering of ADHD symptoms within ASP families suggests that hyperactive and inattentive symptoms reflect common familial underpinnings and not unique familial effects. In contrast, CD seems to reflect unique familial underpinnings distinct from those underlying ADHD.

Adolescent↗

PubMed2005

Comorbidity between ADHD and symptoms of bipolar disorder in a community sample of children and adolescents.

The prevalence and frequency of comorbidity of possible bipolar disorder was examined with attention-deficit hyperactivity disorder (ADHD) in a nonreferred population of twins. Children and adolescents aged 7 to 18 years with a history of manic symptoms were identified from a population-based twin sample obtained from state birth records (n = 1610). The sample was enriched for ADHD; however, there was also a random control sample (n = 466), which allowed a look at the population prevalence of the disorder. Juveniles with threshold or below threshold manic episodes were further assessed for comorbidity with Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) and population-defined ADHD subtypes (from latent class analysis) using Fisher's exact test. Nine juveniles who exhibited DSM-IV manic (n = 1), hypomanic (n = 2) or below threshold episodes (n = 6) were identified. The population prevalence of broadly defined mania in the random sample was 0.2%. The possible manic episodes showed significant comorbidity with population-defined severe combined and talkative ADHD subtypes. It can be concluded that there is a significant association of bipolar symptoms with two population-defined subtypes of ADHD. Episodes of possible bipolar disorders as defined by DSM-IV are uncommon in this nonreferred sample. Children and adolescents with ADHD appear to be only modestly at increased risk for bipolar disorders.

Adolescent↗

PubMed2004

Snoring, sleep quality, and sleepiness across attention-deficit/hyperactivity disorder subtypes.

STUDY OBJECTIVES: To characterize the relationship between pediatric attention-deficit/hyperactivity disorder (ADHD) subtypes, chronic snoring, and indexes of sleep quality and daytime sleepiness. DESIGN: A cross-sectional design with planned comparisons of ADHD (all subtypes) versus general community controls; ADHD Predominantly Inattentive Type (ADHD-I) versus a group with both ADHD Predominantly Hyperactive/Impulsive Type (ADHD-HI) and ADHD Combined Type (ADHD-C); and ADHD-HI versus ADHD-C. SETTING: Subjects recruited from a pediatric clinic, a university psycholgy clinic, and the general community. PARTICIPANTS: Caretakers of 74 children (45 with ADHD, 29 community controls; 53 boys, 21 girls; mean age, 9.6 years; age range, 6 to 16 years). Thirty-two (71.1%) of the children with ADHD were taking stimulant medication and 7 (15.5%) were taking hypnotic medication. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Caretakers completed the Pediatric Sleep Questionnaire (PSQ) and the Children's Sleep-Wake Scale (CSWS). Only the ADHD-HI diagnosis was associated with an increased likelihood of chronic snoring. Sleep quality was poorer among children with ADHD than controls; however, there were no differences in sleep quality across ADHD subtypes. Sleepiness was greater in children with ADHD, especially the ADHD-I Type. CONCLUSIONS: Chronic snoring may be a correlated feature in only a subgroup of the ADHD population, possibly those more likely to be diagnosed with ADHD-HI. Although children with ADHD have poorer sleep quality and greater daytime sleepiness, these 2 features of ADHD are not closely related.

Adolescent↗

PubMed2001

Familiality and heritability of subtypes of attention deficit hyperactivity disorder in a population sample of adolescent female twins.

OBJECTIVE: Attention deficit hyperactivity disorder (ADHD) is a highly heritable but clinically heterogeneous syndrome. The study examined the familiality and heritability of ADHD subtypes as defined by DSM-IV and by latent-class analysis in a population sample of adolescent female twins. METHOD: To determine which elements of ADHD cluster together, latent-class analysis was applied to data obtained from parents on the 18 DSM-IV ADHD symptoms in 4,036 female twins age 13-23 years in a population sample identified from the registry of all births in Missouri for the years 1968-1996. Relative risk and odds ratios were used to assess within-subtype and between-subtype familiality and heritability of both DSM-IV and latent-class ADHD subtypes. RESULTS: Latent-class analysis was most compatible with the existence of three mild and three severe classes of ADHD symptoms in the general population. The three severe classes showed moderate overlap with DSM-IV ADHD subtypes. The primarily inattentive and combined subtypes of DSM-IV ADHD co-clustered within families. The primarily hyperactive/impulsive DSM-IV subtype and the individual latent-class analysis subtypes did not co-cluster. Subtypes defined by both approaches were highly heritable. CONCLUSIONS: Unlike DSM-IV subtypes of ADHD, latent-class ADHD subtypes appear to be independently transmitted in families. These classes may be more appropriate targets for molecular genetic studies of ADHD.

Adolescent↗

PubMed2000

Time perception in boys with attention-deficit/hyperactivity disorder according to time duration, distraction and mode of presentation.

In a recent theoretical model of attention-deficit/hyperactivity disorder (ADHD), Barkley (1997a) predicted that ADHD children experience impairments in their psychological sense of time. This was demonstrated in a series of experiments by Barkley, Koplowicz, Anderson, and McMurray (1997). The present study sought to investigate the effects of ADHD subtype, stimulus duration, mode of presentation (visual versus auditory) and distractors on the performance of a simple time reproduction task. Data were obtained from 44 ADHD children (14 predominantly inattentive and 30 combined type) and 44 age-matched Controls using the Time Perception Application version 1.0 (Barkley, University of Massachusetts Medical Center, 1998). Results revealed that the ADHD children made significantly larger errors on Visual time reproduction tasks than the Controls, regardless of ADHD subtype or the presence of distractors. Furthermore, ADHD children were more likely to overestimate the shorter time intervals (0.5 and 2 s) and underestimate the longer time intervals (3, 4 and 6 s) relative to Controls. No group differences were observed on the auditory time reproduction task, with both ADHD and Control groups consistently underestimating the durations to be reproduced. The results of this study provide further support for the prediction that children with ADHD have an impaired sense of time.

Acoustic Stimulation↗

PubMed2005

Actigraphic and parent reports of sleep patterns and sleep disorders in children with subtypes of attention-deficit hyperactivity disorder.

STUDY OBJECTIVE: To describe parent-reported and actigraphically assessed sleep patterns and sleep disorders in stimulant-medication-free children with attention-deficit/hyperactivity disorder (ADHD), divided according to ADHD subtype. PARTICIPANTS: Seventy-one stimulant-medication-free children with a clinical diagnosis of ADHD (8 girls; mean 8.8 years (SD 2.6), range 3-15 years) recruited from child psychiatry clinics. MEASUREMENTS: ADHD: ADHD Rating Scale DSM IV- Home Version to subdivide children into those with predominantly attention deficit, mainly hyperactivity, and those with both aspects equally. Sleep: Parent-completed sleep diary, clinical history, and 5 nights of actigraphy. RESULTS: Parents reported a wide range of frequently occurring sleep disturbances in their children. However, the objective sleep patterns were not abnormal and did not differ between the ADHD subtypes, and objective sleep patterns did not predict ADHD severity. There was poor correspondence between parent report and actigraphy. Careful clinical consideration of each case suggested that sleep disorders may be widespread in this group of children; only 8 of the 71 children had no discernable likely sleep disorder. Symptoms of sleep-disordered breathing, sleeplessness and reports of restless legs featured prominently. CONCLUSIONS: Parents of children with ADHD may not be accurate reporters of their children's sleep pattern and/or the sleep disturbances that come to parents' attention are not best detected by actigraphy. Results highlight the prominence of parent-reported sleep disturbance in children with ADHD and the need for clinicians to routinely screen for the presence of sleep disorders and assess detailed sleep physiology where indicated.

Adolescent↗

PubMed2001

[Functioning, comorbidity and treatment of 141 adults with attention deficit hyperactivity disorder (ADHD) at a psychiatric outpatient department].

OBJECTIVE: To describe the functioning, comorbidity and treatment of adults with attention deficit hyperactivity disorder (ADHD). DESIGN: Retrospective. METHOD: In the period 1 May 1995 to 31 January 1998, 141 patients aged 18-54 were diagnosed with ADHD at the Delfland Psychiatric Outpatients' Department, Delft, the Netherlands. For all of these patients, data concerning the functioning, comorbidity, and the response to treatment with clonidine (n = 34) or methylphenidate (n = 99), were collected from anamneses, hetero-anamneses and school reports. RESULTS: The most frequent complaints were: mood-swings, rage-outbursts, sensation-seeking behaviour, sleeping disorders, anxiety and depressive symptoms. In 94% (n = 123) of the cases, childhood onset of ADHD symptoms was confirmed by a family member. The distribution of ADHD subtypes was comparable to the distribution in children. Psychiatric comorbidity was common. Treatment with methylphenidate was more effective and better tolerated than treatment with clonidine. CONCLUSION: With respect to ADHD subtypes, patterns of comorbidity and effectiveness of medication, ADHD in the adults studied was comparable with what is known about ADHD in children.

Adrenergic alpha-Agonists↗

PubMed2001

Validity of DSM-IVADHD subtypes in a nationally representative sample of Australian children and adolescents.

OBJECTIVE: To examine the discriminant validity of DSM-IV attention-deficit/hyperactivity disorder (ADHD) subtypes in a nationally representative sample of Australian youths. METHOD: The Diagnostic Interview Schedule for Children, including the symptom-specific impairment questions, was administered to 3,597 parents of children aged 6 to 17 years (response rate = 70%). Parents also completed questionnaires assessing children's emotional and behavioral problems and quality of life. RESULTS: Current DSM-IVADHD prevalence was 7.5% (6.8% with impairment) with inattentive types being more common than hyperactive-impulsive and combined types. ADHD was more prevalent among young males and was linked to social adversity, particularly for combined types. Compared with non-ADHD controls, all three ADHD subtypes were rated as having more emotional and behavioral problems and lower psychosocial quality of life, with combined types consistently rated the most impaired. Combined types received higher ratings than hyperactive-impulsive and inattentive types on externalizing behavior problems, disruption to family activities, and symptom-specific impairments with schoolwork and peer-related activities. Inattentive types were rated as having lower self-esteem, more social and school-related problems, but fewer externalizing problems than hyperactive-impulsive types. CONCLUSION: These findings support the view of DSM-IVADHD subtypes as distinct clinical entities with impairments in multiple domains.

Adolescent↗

PubMed2005

A systematic evaluation of ADHD and comorbid psychopathology in a population-based twin sample.

OBJECTIVE: Clinical and population samples demonstrate that attention-deficit/hyperactivity disorder (ADHD) occurs with other disorders. Comorbid disorder clustering within ADHD subtypes is not well studied. METHOD: Latent class analysis (LCA) examined the co-occurrence of DSM-IV ADHD, oppositional defiant disorder (ODD), conduct disorder (CD), and depression symptoms in a population twin sample. The authors fit separate models for ADHD and comorbid disorder symptoms. Twin concordance ratios (monozygotic versus dizygotic) were compared examining genetic influence on class membership. RESULTS: LCA of ADHD symptoms resulted in seven classes including inattentive, combined, and hyperactive subtypes in 1,616 subjects. The few ADHD symptoms (53.4%) and severe inattentive (12.3%) classes were most frequent. LCA of ODD, CD, and depression symptoms in 1,587 subjects revealed five classes including ODD (19.4%), depression (14.5%), and two composite classes: ODD/CD (6.9%) and ODD/CD/depression (7.2%). Internalizing and externalizing comorbid disorders were present across all ADHD subtypes. Odds ratios (ORs) for twin concordance indicate genetic influence on severe inattentive (OR = 4.18; 95% confidence interval [CI], 1.52-11.53) and combined (OR = 5.25; 95% CI, 1.32-20.78) ADHD classes and ODD (OR = 1.49; 95% CI, 0.70-3.17), ODD/CD (OR = 3.32; 95% CI, 0.57-19.28), and ODD/CD/depression (OR = 1.20; 95% CI, 0.30-4.77) classes. CONCLUSIONS: Internalizing and externalizing disorders did not cluster differentially within ADHD subtypes. LCA may provide a more precise characterization of comorbidity with ADHD.

Adolescent↗

PubMed2006

Meta-analysis of association between a catechol-O-methyltransferase gene polymorphism and attention deficit hyperactivity disorder.

There have been conflicting reports on the association between the Val158/108Met polymorphism of the catechol-O-methyltransferase (COMT) gene and attention deficit hyperactivity disorder (ADHD). Therefore we would like to perform a meta-analysis of previous studies to assess the overall magnitude and significance of the association. Family-based and case-control studies of the association between the COMT gene polymorphism and ADHD were searched systematically and comprehensively. Odds ratios (OR) of association were pooled by the fixed effects model if no significant heterogeneity was present among different studies. Subgroup analysis by gender and ADHD subtypes were also performed. Eleven family-based and two case-control studies were identified. After pooling the results, no significant association between the COMT Vall58/108Met polymorphism and ADHD was found (OR 0.99 (95% CI: 0.88-1.12), P = 0.87). There was also no significant association when the results were stratified by gender or ADHD subtype. There was no significant statistical heterogeneity (chi2 = 12.27, P = 0.2) although clinical heterogeneity was present in the studies, especially the ethnicity of subjects. Sensitivity analysis demonstrated absence of undue influence of any single study. Standard regression analysis showed no significant publication bias. We concluded that no significant association was present between the most common COMT gene polymorphism and ADHD. Further studies should employ larger sample size in more homogeneous subjects. Further investigations in moderator variables and gene-gene and gene-environment interactions are also warranted.

Amino Acid Substitution↗

PubMed2005

Normal attention orienting but abnormal stimulus alerting and conflict effect in combined subtype of ADHD.

Recent pharmacological studies in animals and neuroimaging studies in normal humans suggest that the spatial and nonspatial cues in tasks measuring reflexive attention may be modulated by different neurotransmitter systems. The efficiency with which attention is oriented to explicit spatial cues may be altered by manipulating levels of brain acetylcholine, whereas reactions to nonspatial cues may be influenced by altering brain noradrenaline levels but not acetylcholine levels. In humans, however, previous attention studies have implicated dopamine when either explicit or implicit cueing is used. Some of the differences between animal and human work may be due to inadequate testing of nonspatial cues. To remedy this, we tested adult humans with ADHD that were primarily inattentive (ADHD/I) or combined inattentive/hyperactive (ADHD/C) and controls with the Attention Network Task that assesses both reflexive and voluntary attention and explicitly tests nonspatial cueing. Our results showed that spatial orienting in both subtypes was no different than controls. However, ADHD/C but not ADHD/I subjects had significantly slowed response times to nonspatial cues and cues with spatial conflict. Stimulant medication in a subset of ADHD/C subjects reduced these deficits to control levels. Based on these results, we conclude that ADHD/C subjects orient the focus of their attention normally but are impaired in their reactions both to abrupt visual cues and those that contain conflicting spatial cues.

Adolescent↗

PubMed2003

Fine and gross motor ability in males with ADHD.

In the this study, both fine and gross motor ability of males with attention-deficit-hyperactivity disorder (ADHD) were compared with a group of control children. Three groups of males with the following ADHD subtypes: predominantly inattentive (ADHD-PI; n = 50), hyperactive/impulsive (ADHD-HI; n = 16), or combined (ADHD-C; n = 38) were compared with 39 control males. Mean ages for the control group were 10 years 4 months (SD 1 year 4 months, range 7 years 8 months to 12 years 11 months); for the ADHD-PI group, 10 years (SD 1 year 2 months, range 7 years 10 months to 13 years); for the ADHD-HI group, 9 years 11 months (SD 1 year 2 months), range 7 years 11 months to 12 years 6 months); and for the ADHD-C group 10 years 2 months (SD 1 year 4 months, range 8 to 13 years). The Australian Disruptive Behaviours Scale and Connors' Parent Rating Scale-Revised were used to assess ADHD symptomatology. Verbal IQ was estimated using two verbal subtests of the Wechsler Intelligence Scale for Children, and movement ability was assessed using the Movement Assessment Battery for Children (MABC) and the Purdue Pegboard test. Findings demonstrated that the children with ADHD had significantly poorer movement ability than control children. A high percentage of these children displayed movement difficulties consistent with developmental coordination disorder (DCD). In addition, the current study found that the type and degree of movement difficulty differed between subtypes. The Total Impairment score, as derived from the MABC, was less severe for the ADHD-HI group than the other two ADHD groups, but more severe than for the control group. Males with ADHD-PI and ADHD-C had significantly poorer fine motor ability (p < 0.001) than control males, whereas the ADHD-HI group did not differ significantly from any of the other groups. As children with ADHD only and the control group did not differ significantly on fine motor ability but were significantly better than children categorized with both ADHD and DCD, it was argued that poorer fine motor ability found in children with ADHD could not be attributed to deficits in attention and concentration, but rather to factors relating to their motor ability.

Adolescent↗

PubMed2001

Teacher reports of DSM-IV ADHD, ODD, and CD symptoms in schoolchildren.

OBJECTIVE: To examine the prevalence of DSM-IV symptoms of attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder, and conduct disorder and age, gender, and comorbidity differences between ADHD subtypes. METHOD: Teachers completed a DSM-IV-referenced symptom inventory for 3,006 schoolchildren aged between 3 and 18 years. RESULTS: The screening prevalence rate of ADHD behaviors was 15.8%; rates for individual subtypes were 9.9% for inattentive, 2.4% for hyperactive-impulsive, and 3.6% for combined. The inattentive type was relatively uncommon in preschool children (3.9%), whereas the hyperactive-impulsive type was least common in teenagers (0.8%). Screening prevalence rates were higher for African-American (39.5%) than white (14.2%) students, but did not vary significantly (p < .05) as a function of geographic region or socioeconomic status. ADHD subtypes were rated as more impaired than the non-ADHD group on most measures and were easily differentiated on the basis of comorbid symptoms, social skills impairment, and special education services. CONCLUSIONS: The findings of this and similar studies show relatively high convergence for the prevalence of ADHD behaviors and differences between ADHD subtypes.

Adolescent↗