Stability of Executive Function Deficits in Girls with ADHD: A Prospective Longitudinal Followup Study into Adolescence

Neuropsychological deficits in the executive system are major sources of morbidity in individuals with attention-deficit/hyperactivity disorder (ADHD). We conducted a 5-year longitudinal study of girls with (N = 140) and without (N = 122) ADHD, aged 6–18 years at baseline. Neuropsychological functioning was assessed using standard neuropsychological testing assessing executive functions (EFs). Girls with ADHD were significantly more impaired than controls in all neuropsychological domains except set shifting. Despite variability in the stability of individual domains of EFs, the majority (79%) of girls with ADHD that met the categorical definition of executive function deficits (EFDs, defined as two or more EF tasks impaired) at baseline continued to have EFDs at the five-year followup. These findings document the stability of EFDs in girls with ADHD from childhood into adolescence.     

Impact of gender and age on executive functioning: do girls and boys with and without attention deficit hyperactivity disorder differ neuropsychologically in preteen and teenage years?

ADHD is known to have neuropsychological correlates, characterized mainly by executive function (EF) deficits. However, most available data are based on studies of boys through age 12. Our goal was to assess whether girls with ADHD express neuropsychological features similar to those found in boys, and whether these impairments are found in both preteen and teen samples. Participants were 101 girls and 103 boys with DSM--III--R ADHD, and 109 comparison girls and 70 boys without ADHD, ages 9 to 17 years. Information on neuropsychological performance was obtained in a standardized manner blind to clinical status. Primary regression analyses controlled for age, socioeconomic status, learning disability, and psychiatric comorbidity. Girls and boys with ADHD were significantly more impaired on some measures of EFs than healthy comparisons but did not differ significantly from each other. With the exception of 1 test score there were no significant Sex × Diagnosis interactions. Moreover, there were no more significant interactions among age, gender, and diagnosis than would be expected by chance. Neuropsychological measures of EFs were comparably impaired in girls compared to boys with ADHD, and these impairments are found at ages 9 to 12 and ages 13 to 17. These findings suggest that executive dysfunctions are correlates of ADHD regardless of gender and age, at least through the late teen years.     

Impact of executive function deficits and attention-deficit/hyperactivity disorder (ADHD) on academic outcomes in children

The association between executive function deficits (EFDs) and functional outcomes were examined among children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Participants were children and adolescents with (n = 259) and without (n = 222) ADHD, as ascertained from pediatric and psychiatric clinics. The authors defined EFD as at least 2 executive function measures impaired. Significantly more children and adolescents with ADHD had EFDs than did control participants. ADHD with EFDs was associated with an increased risk for grade retention and a decrease in academic achievement relative to (a) ADHD alone, (b) controlled socioeconomic status, (c) learning disabilities, and (d) IQ. No differences were noted in social functioning or psychiatric comorbidity. Children and adolescents with ADHD and EFDs were found to be at high risk for significant impairments in academic functioning. These results support screening children with ADHD for EFDs to prevent academic failure.     

Neuropsychological functioning of girls with attention-deficit/hyperactivity disorder followed prospectively into adolescence: evidence for continuing deficits?

The current study prospectively followed girls with attention-deficit/hyperactivity disorder (ADHD), along with a matched comparison sample, 5 years after childhood neuropsychological assessments. Follow-up neuropsychological measures emphasized attentional skills, executive functions, and language abilities. Paralleling childhood findings, the childhood-diagnosed ADHD group displayed moderate to large deficits in executive/attentional performance as well as in rapid naming relative to the comparison group at follow up (M-sub(age) 14.2 years). ADHD-inattentive versus ADHD-combined contrasts were nonsignificant and of negligible effect size, even when a refined, sluggish cognitive tempo subgroup of the inattentive type was examined. Although ADHD versus comparison group differences largely withstood statistical control of baseline demographics and comorbidities, control of childhood IQ reduced executive function differences to nonsignificance. Yet when the subset of girls meeting diagnostic criteria for ADHD in adolescence was compared with the remainder of the participants, neuropsychological deficits emerged even with full statistical control. Overall, childhood ADHD in girls portends neuropsychological and executive deficits that persist for at least 5 years.     

Neuropsychological performance deficits in adults with attention deficit/hyperactivity disorder.

Neuropsychological deficits in children diagnosed with attention deficit/hyperactivity disorder (ADHD) have been well documented utilizing various neuropsychological tests. Only recently has research begun to examine if similar deficits are present in adults with ADHD. A neuropsychological testing battery was constructed that assessed verbal learning and memory, psychomotor speed, and sustained attention--all demonstrated to be deficient in individuals with ADHD. Fifty-six self-referred nonmedicated adults with a DSM-IV diagnosis of ADHD and 38 normal comparison adults participated. ADHD adults demonstrated verbal and nonverbal memory deficits and decreased psychomotor speed compared to normal controls. Differences between ADHD and normal adults were not documented on traditional measures of executive functioning. A pattern of results emerged whereby ADHD adults' performance, particularly with regard to psychomotor speed, became more impaired as task complexity increased. This study's results largely corroborate similar neuropsychological testing results in ADHD children and recent ADHD adult findings, and support a frontal lobe dysfunction hypothesis of ADHD.     

Neuropsychological functioning in girls with attention-deficit/hyperactivity disorder with and without learning disabilities

The authors' goal was to assess neuropsychological performance in girls with attention-deficit/hyperactivity disorder (ADHD) and evaluate the role of comorbid learning disabilities (LDs). Participants were 140 girls with ADHD and 122 girls without ADHD, ages 6-17 years. Neuropsychological performance was measured in a standardized manner, blind to clinical status. LD was defined by a combined regression-based and low-achievement classification. ADHD was associated with modest, but significant, neuropsychological impairment, as measured with an aggregate measure of performance and with the Stroop Color-Word Test, independent of age, social class, IQ, and psychiatric comorbidity. Neuropsychological deficits were most pronounced in girls with both ADHD and an LD and in those without medications. These results extend to females the previously documented association of LDs with neuropsychological functioning in males with ADHD.     

Learning disabilities and executive dysfunction in boys with attention-deficit/hyperactivity disorder

The effect of comorbid reading or arithmetic learning disabilities (LDs) on neuropsychological function in attention-deficit/hyperactivity disorder (ADHD) was studied. Participants were young males diagnosed with ADHD, with and without LD, and non-ADHD, non-LD male controls of similar age. LD was defined by combined regression-based and low-achievement classifications. Analyses adjusted for the effect of psychiatric comorbidity, age, and socioeconomic status on neuropsychological function. Children who had both ADHD and LD were significantly more impaired on both executive and nonexecutive functions than ADHD children without LD. Neuropsychological performance was most impaired in ADHD with combined arithmetic and reading disability. These data indicate that comorbid LD, especially arithmetic disability, significantly increases the severity of executive function impairment in ADHD.     

Neuropsychological performance in adult attention-deficit hyperactivity disorder: meta-analysis of empirical data.

Attention-deficit hyperactivity disorder (ADHD) is increasingly recognized not only in children but also in adults. Neuropsychological tests are important tools to quantify the attentional and/or cognitive deficits of patients compared to controls. The present meta-analysis integrates 24 empirical studies reporting results of at least one of 50 standard neuropsychological tests comparing adult ADHD patients with controls. The 50 tests were categorized into the following 10 functional domains: verbal ability, figural problem solving, abstract problem solving, executive function, fluency, simple attention, sustained attention, focused attention, verbal memory, figural memory. For each domain a pooled effect size d' was calculated. Complex attention variables and verbal memory discriminated best between ADHD patients and controls. Effect sizes for these domains were homogeneous and of moderate size (d' between 0.5 and 0.6). In contrast to results reported in children, executive functions were not generally reduced in adult ADHD patients.     

Executive functioning in adult ADHD: a meta-analytic review

BACKGROUND: Several theoretical explanations of ADHD in children have focused on executive functioning as the main explanatory neuropsychological domain for the disorder. In order to establish if these theoretical accounts are supported by research data for adults with ADHD, we compared neuropsychological executive functioning and non-executive functioning between adults with ADHD and normal controls in a meta-analytic design. METHOD: We compared 13 studies that (1) included at least one executive functioning measure, (2) compared the performance of an adult ADHD group with that of an adult normal control group, (3) provided sufficient information for calculation of effect sizes, and (4) used DSM-III-R or DSM-IV criteria to diagnose ADHD. RESULTS: We found medium effect sizes both in executive functioning areas [verbal fluency (d= 0-62), inhibition (d = 0-64 and d = 0.89), and set shifting (d = 0.65)] and in non-executive functioning domains [consistency of response (d = 0.57), word reading (d = 0.60) and color naming (d = 0.62)]. CONCLUSIONS: Neuropsychological difficulties in adult ADHD may not be confined to executive functioning. The field is in urgent need of better-designed executive functioning tests, methodological improvements, and direct comparisons with multiple clinical groups to answer questions of specificity.     

Executive function and attention deficit hyperactivity disorder: stimulant medication and better executive function performance in children.

BACKGROUND: Executive function deficits have been reported repeatedly in children with Attention Deficit Hyperactivity Disorder (ADHD). Stimulant medication has been shown to be effective in improving cognitive performance on most executive function tasks, but neuropsychological tests of executive function in this population have yielded inconsistent results. Methodological limitations may explain these inconsistencies. This study aimed to measure executive function in medicated and non-medicated children with ADHD by using a computerized battery, the Cambridge Neuropsychological Test Automated Battery (CANTAB), which is sensitive to executive function deficits in older patients with frontostriatal neurological impairments. METHODS: Executive function was assessed in 30 children with ADHD: 15 were stimulant medication naive and 15 were treated with stimulant medication. These two groups were compared to 15 age, sex and IQ matched controls. RESULTS: The unmedicated children with ADHD displayed specific cognitive impairments on executive function tasks of spatial short-term memory, spatial working memory, set-shifting ability and planning ability. Impairments were also seen on spatial recognition memory and delayed matching to sample, while pattern recognition memory remained intact. The medicated children with ADHD were not impaired on any of the above executive function tasks except for deficits in spatial recognition memory. CONCLUSIONS: ADHD is associated with deficits in executive function. Stimulant medication is associated with better executive function performance. Prospective follow-up studies are required to examine these effects.     

Prospective follow-up of girls with attention-deficit/hyperactivity disorder into adolescence: Evidence for continuing cross-domain impairment

The authors performed 5-year prospective follow-up (retention rate = 92%) with an ethnically diverse sample of girls, aged 11-18 years, who had been diagnosed in childhood with attention-deficit/ hyperactivity disorder (ADHD; N = 140) and a matched comparison group (N = 88). Hyperactive-impulsive symptoms were more likely to abate than inattentive symptoms. Across multiple domains of symptoms and functional impairment, girls with ADHD continued to display deficits of moderate to large effect size in relation to the comparison girls, but few differences emerged between the inattentive versus combined types. Follow-up effects withstood statistical control of crucial covariates for most outcomes, meaning that there were specific effects of childhood ADHD on follow-up status; in other instances, baseline disruptive disorders accounted for adolescent effects. For outcomes identical at baseline and follow-up, girls with ADHD showed more improvement across time than comparison girls (except for math achievement). Overall, ADHD in girls portends continuing impairment 5 years after childhood ascertainment.     

Neuropsychological functioning in stimulant-naive boys with hyperkinetic disorder

BACKGROUND: Although children with hyperkinetic disorder and/or attention deficit hyperactivity disorder (ADHD) show disordered executive neuropsychological functioning, the nature of these changes remains controversial. Additionally, impairments in non-executive neuropsychological functioning have been relatively unexplored. Here, the authors describe the neuropsychological functioning of a sample of stimulant drug-naive boys with hyperkinetic disorder on a battery of neuropsychological tasks sensitive to impairments of both executive and non-executive functions. METHOD: Seventy-five stimulant drug-naive boys meeting diagnostic criteria for ICD-10 hyperkinetic disorder were compared with 70 healthy developing controls matched for age but not IQ on computerized tests of neuropsychological functioning from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and a Go/No-Go inhibition task. RESULTS: Boys with hyperkinetic disorder exhibited impairments on tasks with a prominent executive component--working memory, planning, strategy formation, attentional set-shifting and on a reaction time task. However, they were also impaired on tasks without prominent executive components--pattern and spatial recognition, spatial span, delayed matching to sample and paired associates learning. Contrary to predictions, no impairment was observed on the Go/No-Go inhibition task. CONCLUSIONS: Medication-naive boys with hyperkinetic disorder displayed a broad range of neuropsychological impairments. Deficits were demonstrated on tasks with and without prominent executive components. Impairments were not confined to tasks dependent upon frontostriatal functioning, cannot wholly be explained by deficits in inhibitory control, nor can they be attributed to intelligence or previous exposure to stimulant medication.     

Relationships between neuropsychological measures of executive function and behavioral measures of ADHD symptoms and comorbid behavior.

OBJECTIVE: The aim of this study was to examine the relationship between executive functions (EFs), as measured by neuropsychological tests, and symptoms of attention deficit hyperactivity disorder (ADHD) and comorbid behavior, as rated by parents and teachers. As intelligence and language ability are important covariates they were also assessed. METHOD: The sample consisted of 43 children aged 7-11 years who were referred for neuropsychological assessment at a tertiary clinical facility. Most of the children had the diagnosis of ADHD combined or inattentive type. Different aspects of EFs were assessed. RESULTS: EFs were not significantly related to symptoms of ADHD, but only to comorbid symptoms of depression and autistic symptomatology. Language ability rather than EFs best predicted teacher ratings of inattention. CONCLUSIONS: The results of the study do not support the EF theory of ADHD. The importance of screening for comorbid language disorders in children referred for ADHD is emphasized.     

Neuropsychological functioning in relatives of girls with and without ADHD

BACKGROUND: A limited number of studies have examined neuropsychological functioning in the family members of ADHD youth, and none have focused exclusively on relatives of females. METHOD: Structured diagnostic interviews and neuropsychological batteries were administered to parents and siblings enrolled in a family study of girls with and without ADHD. Relatives were stratified into three groups: relatives of DSM-IV ADHD probands with ADHD (n = 106), relatives of ADHD probands without ADHD (n = 189) and relatives of controls without ADHD (n = 243). Analyses were also conducted on a subgroup of families in which more than one member had RESULTS: The neuropsychological battery as a whole distinguished affected and unaffected ADHD relatives from controls. The Wechsler Oral Arithmetic subtest, the Stroop Word, Color and Color-Word subscales were impaired in affected ADHD relatives, as were the WRAT-R Arithmetic and Reading subtests. Only the Stroop Color-Word and Interference subtests and the WRAT-R Arithmetic subtest showed significant impairments in unaffected relatives. In multiplex families, additional impairments were found in unaffected relatives on the Stroop Color subtest and the Wechsler Oral Arithmetic subtest. Analyses based on DSM-III-R diagnoses produced nearly identical results. Minor differences emerged across relatives of probands with different DSM-IV subtypes. CONCLUSIONS: Data were consistent with our previous study of relatives of boys with ADHD. Neuropsychological impairments in relatives of female ADHD probands were primarily associated with the diagnosis of ADHD, but subtle cognitive impairments that index familial vulnerability to the disorder may exist.     

Neuropsychological functioning in people with ADHD across the lifespan

ADHD is defined by behavioral characteristics similar to neuropsychological disorders of executive dysfunction. This paper is a literature review of the neurocognitive characteristics of ADHD from early childhood through adulthood. The author addresses the development of the concept of attention and executive function (EF) deficits in ADHD, clinical neuropsychological studies of pre-teenage children, teenagers and adults with ADHD, gender and the role of psychiatric co-morbidity including the relationship of learning disabilities to ADHD, heterogeneity of neuropsychological dysfunctions, experimental neuropsychological studies, the relationship of brain structure to function, psychopharmacology of ADHD, and clinical neuropsychological assessment. The group data clearly supports the hypothesis that executive dysfunctions are correlates of ADHD regardless of gender and age, and these EF deficits are exacerbated by co-morbidity with learning disabilities such as dyslexia. However, there is limited data on children under the age of 5, teenagers from age 13-18, and adults with ADHD over the age of 40. Studies of individual classification of people with ADHD compared to healthy, non-psychiatric controls do not support the use of neuropsychological tests for the clinical diagnosis of ADHD, and indicate that not all persons with ADHD have EF deficits. Some persons with ADHD may have deficits in brain reward systems that are relatively independent of EF impairments. Future research should clarify the multiple sources of ADHD impairments, continue to refine neuropsychological tools optimized for assessment, and incorporate longitudinal, developmental designs to understand ADHD across the lifespan.     

Neuropsychological correlates of ADHD symptoms in preschoolers

The authors examined the neuropsychological status of 22 preschoolers at risk for attention-deficit/hyperactivity disorder (ADHD) and 50 matched control children, using measures of nonverbal working memory, perceptual and motor inhibition, and memory for relative time. All tasks included paired control conditions, which allowed for the isolation of discrete executive function constructs. Group differences were evident on several measures of neuropsychological functioning; however, after accounting for nonexecutive abilities, no deficits could be attributed to specific functions targeted by the tasks. Performance on executive measures was not related to objective indices of activity level or ratings of ADHD symptoms. Yet, the fact that at-risk preschoolers were highly symptomatic casts doubt on whether executive function deficits and/or frontostriatal networks contribute etiologically to early behavioral manifestations of ADHD.     

The relation between working memory components and ADHD symptoms from a developmental perspective

The objective was to examine the relations between attention deficit hyperactivity disorder (ADHD) symptoms and four working memory (WM) components (short-term memory and central executive in verbal and visuospatial domains) in 284 6-16-year-old children from the general population. The results showed that verbal and visuospatial short-term memory and verbal central executive uniquely contributed to inattention symptoms. Age interacted with verbal short-term memory in predicting inattention, with the relation being stronger in older children. These findings support the notion of ADHD as a developmental disorder, with changes in associated neuropsychological deficits across time. The results further indicate ADHD-related deficits in several specific WM components.     

Neuropsychological differences among empirically derived clinical subtypes of schizophrenia.

Neuropsychological profile differences between empirically derived clinical subtypes of schizophrenia were examined. Two hundred five patients and 209 demographically matched controls were administered a neuropsychological battery examining 8 domains. Subtypes included negative, disorganized, paranoid, Schneiderian, and mild. All subtypes displayed a neuropsychological profile of generalized impairment with greater deficits in learning, memory, and attention. Results were suggestive of diffuse cognitive dysfunction in schizophrenia with more severe deficits in learning and memory relative to executive skills. This pattern of greater learning and memory impairment was pronounced for disorganized patients. In contrast, paranoid patients outperformed disorganized and negative patients in several domains. These findings reflect bilateral frontal-temporal dysfunction, particularly in disorganized and negative patients. Subtype differences highlight the importance of conceptualizing schizophrenia as a multifocal disorder.     

Stability and course of neuropsychological deficits in manic and depressed bipolar patients compared to patients with Major Depression

BACKGROUND: Neuropsychological functioning varies across different subgroups of patients with affective disorders; yet there have only been a few studies pointing out distinctive neuropsychological profiles and following-up possible changes in this functioning. The aim of this study was to compare neuropsychological functioning across remitted manic or depressed patients with bipolar disorder compared to remitted patients with Major Depression and to explore the course of their cognitive functioning. METHODS: 30 patients with Major Depression, 17 manic bipolar patients, and 22 depressed bipolar patients were assessed for memory, attention, and executive functions using the Auditory Verbal Learning Test (AVLT), the Modified Card Sorting Test (MCST), the Attention Network Test (ANT), and Stop-Signal Task. Neuropsychological assessment was performed at discharge and seven weeks after discharge. RESULTS: The three groups showed different neuropsychological performance at discharge. Regarding selective attention and speed of responding the manic bipolar patients displayed poorer performance than the other two groups. Furthermore, follow-up assessment revealed that although all patient groups demonstrated an overall improvement, some deficits (especially in executive functions) remain. Manic bipolar patients showed again the worst performance. Depressed bipolar patients, however, were not observed to show a poorer outcome than depressed unipolar patients. CONCLUSIONS: This study provides further evidence for distinct neuropsychological functioning in patients with affective disorders depending on their state of illness. Furthermore, it supports the hypothesis that especially manic bipolar patients stay impaired in certain cognitive functions after remission. These findings may be of clinical relevance regarding treatment and prevention programs and emphasize the need of further research investigating stability and course of patients with mood disorders.