Hippocampus and amygdala morphology in attention-deficit/hyperactivity disorder

CONTEXT: Limbic structures are implicated in the genesis of attention-deficit/hyperactivity disorder (ADHD) by the presence of mood and cognitive disturbances in affected individuals and by elevated rates of mood disorders in family members of probands with ADHD. OBJECTIVE: To study the morphology of the hippocampus and amygdala in children with ADHD. DESIGN: A cross-sectional case-control study of the hippocampus and amygdala using anatomical magnetic resonance imaging. SETTINGS: University research institute. PATIENTS: One hundred fourteen individuals aged 6 to 18 years, 51 with combined-type ADHD and 63 healthy controls. MAIN OUTCOME MEASURES: Volumes and measures of surface morphology for the hippocampus and amygdala. RESULTS: The hippocampus was larger bilaterally in the ADHD group than in the control group (t = 3.35; P < .002). Detailed surface analyses of the hippocampus further localized these differences to an enlarged head of the hippocampus in the ADHD group. Although conventional measures did not detect significant differences in amygdalar volumes, surface analyses indicated the presence of reduced size bilaterally over the area of the basolateral complex. Correlations with prefrontal measures suggested abnormal connectivity between the amygdala and prefrontal cortex in the ADHD group. Enlarged subregions of the hippocampus tended to accompany fewer symptoms. CONCLUSIONS: The enlarged hippocampus in children and adolescents with ADHD may represent a compensatory response to the presence of disturbances in the perception of time, temporal processing (eg, delay aversion), and stimulus seeking associated with ADHD. Disrupted connections between the amygdala and orbitofrontal cortex may contribute to behavioral disinhibition. Our findings suggest involvement of the limbic system in the pathophysiology of ADHD.     

Treatment of adults with attention-deficit/hyperactivity disorder

This review focuses on the treatment of attention deficit hyperactivity disorder (ADHD) in adults. It briefly addresses prevalence, diagnostic and differential diagnostic issues specific to adults. Stimulant medication, non-stimulant medication, and psychosocial treatments are thoroughly reviewed. For each class of medication possible mechanism of action, efficacy and side effects are summarized. Special attention is given to the pharmacological treatment for patients with adult ADHD and various comorbidities. In summary, stimulant medications are most effective and combined medication and psychosocial treatment is the most beneficial treatment option for most adult patients with ADHD.     

Treatment of adults with attention-deficit/hyperactivity disorder

This review focuses on the treatment of attention deficit hyperactivity disorder (ADHD) in adults. It briefly addresses prevalence, diagnostic and differential diagnostic issues specific to adults. Stimulant medication, non-stimulant medication, and psychosocial treatments are thoroughly reviewed. For each class of medication possible mechanism of action, efficacy and side effects are summarized. Special attention is given to the pharmacological treatment for patients with adult ADHD and various comorbidities. In summary, stimulant medications are most effective and combined medication and psychosocial treatment is the most beneficial treatment option for most adult patients with ADHD.     

Cognitive control in adults with attention-deficit/hyperactivity disorder

The objective of the present study was to investigate the ability of adults with Attention-Deficit/Hyperactivity Disorder (ADHD) to direct their attention and exert cognitive control in a forced instruction dichotic listening (DL) task. The performance of 29 adults with ADHD was compared with 58 matched controls from the Bergen Dichotic Listening Database (N > 1500). Participants in the Bergen DL task listen to and report from conflicting consonant-vowel combinations (two different syllables presented simultaneously, one to each ear). They are asked to report the syllable they hear (non-forced condition), or to focus and report either the right- or left-ear syllable (forced-right and forced-left condition). This procedure is presumed to tap distinct cognitive processes: perception (non-forced condition), orienting of attention (forced-right condition), and cognitive control (forced-left condition). Adults with ADHD did not show significant impairment in the conditions tapping perception and attention orientation, but were significantly impaired in their ability to report the left-ear syllable during the forced-left instruction condition, whereas the control group showed the expected left-ear advantage in this condition. This supports the hypothesis of a deficit in cognitive control in the ADHD group, presumably mediated by a deficit in a prefrontal neuronal circuitry. Our results may have implications for psychosocial adjustment for persons with ADHD in educational and work environments.     

Disentangling deficits in adults with attention-deficit/hyperactivity disorder

CONTEXT: A lack of inhibitory control has been suggested to be the core deficit in attention-deficit/hyperactivity disorder (ADHD), especially in adults. This means that a primary deficit in inhibition mediates a cascade of secondary deficits in other executive functions, such as attention. Impaired stopping has been claimed to support the inhibition hypothesis. However, executive functions such as inhibition and attention are hard to disentangle. OBJECTIVE: To use event-related potentials in adult patients with ADHD to show that impaired stopping is associated with abnormalities of attention. DESIGN: The stop signal task was presented to 24 adults with ADHD combined subtype and 24 controls. Stop event-related potentials are distorted by overlap from event-related potentials to other stimuli in close temporal proximity, but we applied a method (Adjar level 2) to effectively remove this overlap. RESULTS: In line with an inhibitory control deficit, the stop signal reaction time was longer in adults with ADHD (F(1,46) = 7.12, P<.01) whereas there was no significant difference for go stimulus reaction time. Overlap-free stop event-related potentials revealed smaller stop P3s in adults with ADHD (F(1,44) = 4.20, P<.05). In children with ADHD, this has been interpreted to reflect deficient inhibitory control. However, controls were also found to have larger early responses in the auditory cortex (N1) when stop signals resulted in successful stops, relative to failed stops, signifying increased attention (F(1,23) = 11.88, P<.01). This difference was completely absent in adults with ADHD. CONCLUSIONS: Disturbed attentional processing of the stop signal contributed to impaired stopping in adults with ADHD. This finding may have implications for treatment.     

Bupropion treatment of attention-deficit hyperactivity disorder in adults

The authors treated 19 adults with attention-deficit hyperactivity disorder with an open trial of bupropion. These patients had received maintenance stimulant medication or monoamine oxidase inhibitors for an average of 3.7 years. Fourteen of the patients experienced moderate to marked benefit from bupropion; ten of these patients chose to continue bupropion rather than their former medication. These results suggest that bupropion may be an alternative to stimulants in treating some adults with attention-deficit hyperactivity disorder.     

Impact of comorbidity in adults with attention-deficit/hyperactivity disorder

Persistence of attention-deficit/hyperactivity disorder (ADHD) into adulthood and male-to-female ratios of this disorder in childhood and adulthood have been controversial issues in the ADHD diagnosis in adults. Research has resolved these controversies and in turn provided support for the validity of the diagnosis in adults. Support for the diagnosis can also be found in data that show the lifetime prevalence rate for comorbid conditions such as antisocial disorders, mood and anxiety disorders, and substance abuse disorders to be consistent across pediatric and adult populations with ADHD. These coexisting conditions add not only to the impairment associated with ADHD in adults but also to the disorder's economic burden, the extent of which is currently unknown. However, adults with the disorder, like children, probably have higher health care use and costs than people without the disorder. Little, too, is known about the social cost of ADHD, but if left untreated, the impact may be substantial. Research to determine the occupational costs associated with ADHD is ongoing, but until that and other cost-of-illness data are available, studies on the economic costs of the comorbid conditions depression, anxiety, and substance abuse and dependence may be used to make suppositions about the economic impact of ADHD in adults. More studies are needed on the outcomes of adults with this disorder, especially cost-of-illness studies.     

Characteristics of adults with attention-deficit/hyperactivity disorder and past conduct disorder

Objective: DSM‐IV Attention‐deficit/hyperactivity disorder (ADHD) comorbid with DSM‐IV conduct disorder (CD) in childhood/adolescence has been proposed as a ‘distinct subtype’. The present study investigated subsequent psychopathological characteristics of this proposed subtype in adults. Method: Questionnaires were completed by 71 adults (mean age 29.6 years) with ADHD and their informants. Results: The 39 subjects with a history of past CD, when compared with the remaining subjects, were associated with significantly increased ratings of aspects of ADHD‐related impulsivity, with features of all three DSM‐IV ‘Clusters’ of personality disorders (PDs) (in particular of ‘Cluster B’ PDs) and with other psychopathology. Also, there were significant correlations between the number of endorsed past CD criteria and various self‐ratings of psychopathology. Conclusion: The results indicate the psychopathological characteristics of adults with a history of the proposed ‘ADHD with CD’ subtype. The findings are relevant to future studies of ADHD subtypes in adults.     

Neuropsychological function in adults with attention-deficit/hyperactivity disorder.

This article reviews the current state of the literature pertaining to the neuropsychological dysfunctions that are found in children and adults with attention-deficit/hyperactivity disorder (ADHD). Be-cause considerable controversy has existed about the nature and validity of adult ADHD, this article will aid clinicians in develop-ing a better understanding of the empirical literature on neuropsychological function in ADHD throughout the lifespan.     

Seasonal affective symptoms in adults with residual attention-deficit hyperactivity disorder.

There is evidence from clinical, epidemiological, and neuroimaging studies that attention-deficit hyperactivity disorder (ADHD) and seasonal affective disorder (SAD) may have several features in common. To assess seasonal affective symptoms in adults with ADHD, 115 individuals attending an adult ADHD clinic in Toronto, Ontario, Canada were asked to complete the Seasonal Pattern Assessment Questionnaire (SPAQ). From this clinic population of 115, a total of 56 completed SPAQs were returned. Assuming that all individuals failing to complete the SPAQ were nonseasonal and depending on which case-finding criteria were used, the rate of SAD in the overall clinic sample was estimated at either 10.4% (Terman criteria) or 19.1% (criteria of Kasper et al.). These prevalence rates are significantly greater than the rates reported in large population surveys at similar latitudes. There was an apparent relationship between female gender, impulsive-subtype ADHD, and seasonality. Future studies to examine whether core symptoms of ADHD fluctuate across the seasons and to assess the efficacy of light therapy in "seasonal" ADHD patients would be of great theoretical and clinical interest.     

The consequences of attention-deficit/hyperactivity disorder in adults

Until recently, attention-deficit/hyperactivity disorder (ADHD) was a diagnosis reserved for children and adolescents as it was believed to dissipate before adulthood. New evidence, however, supports the persistence of ADHD beyond adolescence, and it is now recognized as a chronic neurobehavioral disorder in adults. Adults with ADHD have difficulties with school, work, family interactions, and social activities. Although treatments are available for adult ADHD, many patients never receive an accurate diagnosis that would afford them appropriate therapeutic intervention. If left untreated, adult ADHD can cause significant personal, social, and economic burdens that can have a negative impact on overall quality of life. This article discusses how ADHD presents in adults and the effects of the disorder on educational, occupational, interpersonal, and social functioning. Currently available treatments for ADHD in adults are also reviewed.     

Psychosocial treatments for adults with attention-deficit/hyperactivity disorder.

This article discussed some ways in which a history of failure experiences can enhance negative affect and cognitive avoidance and further impair attentional and organizational abilities associated with ADHD. Accordingly,psychosocial interventions have two targets: providing training in organizational and attentional skills while addressing patterns that motivate demand-related distress and avoidance of these skills. The authors conceptualized these interventions as creating the conditions where patients best can use existing abilities and the benefits offered by medication treatment. As rep-resented by a small but growing literature, there are encouraging signs that structured skill-building treatments of this kind offer benefit to adults with ADHD. Further research on these strategies in the context of well-controlled trials is an essential step for helping reduce disability and distress among this cohort of patients.     

Diagnosis and evaluation of adults with attention-deficit/hyperactivity disorder.

Although some areas of adult ADHD knowledge remain unclear, there isa strong sense of how to proceed with diagnosis using current DSM-IV criteria as a guide. Thorough clinical interview, aided by the use of rating scales for current symptoms and collateral information about childhood from parents or siblings, forms the backbone of the assessment. The poor psychosocial outcomes of patients with ADHD. often a consequence of unrecognized,untreated disorder manifestation, also can serve as a diagnostic indicator. Diagnostic and symptom assessment scales also can be a significant helpin diagnosing and establishing the symptoms of ADHD in adults. It is important to remember that according to DSM-IV, the cardinal criteria for making the diagnosis are the presence of sufficient current symptoms and impairment in two realms (home, school/work, and social interactions). Accordingly, adult ADHD remains a clinical diagnosis, and the clinician-administered interview remains the cornerstone of diagnostic evaluation.     

Quantitative EEG analysis in dexamphetamine-responsive adults with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (AD/HD) is recognized as a disorder affecting children and adolescents and has more recently been documented to continue into adulthood in a proportion of patients. One of the common treatments for AD/HD is the use of stimulant medications. Numerous studies have examined the therapeutic effects of stimulant medications in children, adolescents and adults with the disorder, reporting improvements in attention, concentration, and hyperactive and impulsive behaviours. Several studies have also examined the effects of stimulants on the electroencephalograph (EEG) of children and adolescents with the disorder, but to date, there have been no studies examining the effects of stimulant medication on the EEG of adults with AD/HD. In the present study, we aimed to replicate previous EEG findings in adults with AD/HD relative to controls and to examine whether there was any change in this profile following treatment with dexamphetamine. The EEG was recorded at rest in an eyes-open condition from 50 adults diagnosed with AD/HD and assessed as good responders to treatment, both before and after treatment with dexamphetamine, and 50 control subjects. The pre-medication results are similar to those found in previous research that compared the EEGs of adults with AD/HD and control subjects. Following medication, there was a significant reduction in slow wave activity in the AD/HD group to levels similar to those in the control group. These results suggest that changes in brain function of good responders to dexamphetamine, as reflected in the EEG, may underlie the behavioural improvements observed in the clinical setting.     

Clinical assessment and diagnosis of adults with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent disorder in adult psychiatry, particularly in out-patient settings. There are no objective, laboratory-based tests that can establish this diagnosis. Present diagnostic criteria for ADHD are formulated primarily according to behavior in childhood, based on age inappropriate and impairing levels of hyperactivity, impulsivity and inattention. Other symptoms, such as mood instability and frustration intolerance, are not included in current criteria for ADHD, but are very prevalent in this patient group. ADHD is often comorbid with alcohol and substance abuse and other psychiatric disorders, in particular anxiety and personality disorders. Thus, the diagnostic assessment should both include a comprehensive clinical interview, rating scales for past and present symptoms and collateral information from multiple informants, as well as assessment of a broader spectrum of psychiatric and somatic conditions. As ADHD is associated with changes in brain function mediating different aspects of neuropsychological functions, assessment of those functions is important to understand the symptom patterns and to develop targeted treatment programs. Some topics for further research and for future developments of diagnostic criteria and tools are highlighted.     

Driving impairments in teens and adults with attention-deficit/hyperactivity disorder.

Available research provides compelling evidence that ADHD is associated with significantly increased risks for various adverse outcomes while driving, including increased traffic citations (particularly speeding), motor vehicle crashes for which the driver is at fault, repeated crash occurrences,and more severe crashes as determined from dollar damage and likelihood of bodily injuries from the crash. Not surprisingly, teens and adults with ADHD are more likely to have their licenses suspended and even fully revoked. Research further suggests that these driving risks cannot be accounted for by the comorbid disorders likely to be associated with ADHD, such as ODD, conduct disorder (CD), depression, or anxiety, or by lower than normal levels of intelligence.Recent attempts to study the processes or mechanisms involved in driving in adults with ADHD offer some explanation of how the disorder conveys such increased risks. Driving can be conceptualized usefully as involving at least three or more dimensions or levels, including basic cognitive abilities necessary for driving (operational), actual skills for maneuvering the vehicle in traffic (tactical), and the more executive, goal-directed aspects of driving(strategic). The findings of studies indicate that ADHD interferes with the basic operational components of driving by means of the impairments it produces in attention, resistance to distraction, response inhibition, slower and more variable reaction time, and the capacity to follow rules that may compete with ongoing sensory information. Accumulating evidence also points to a problem in the tactical level of driving, such that those with ADHDrate themselves and are rated by others as employing less safe driving habits during their normal operation of a vehicle than are adults in community control groups. Although this has been more elusive to demonstrate through the use of simple laboratory-based driving simulators. more modern virtual reality driving platforms offer greater promise in providing more realistic appraisals of driving performance and thus more direct evidence of the problems that occur at the tactical level from the disorder. Research has not examined the impact of ADHD at the higher strategic level or goal-directed aspects of driving. But given the mounting evidence that ADHD adversely affects executive functioning in adults, the author and colleagues anticipate that this level also will be found to be impaired in adults with ADHD. Indeed,it recently has been shown that adults with ADHD overestimate their driving abilities relative to normal adults, a problem that likely can be ascribed to more limited self-awareness and related meta-cognitive abilities for self-evaluation arising from the disorder.Although further research on the driving problems posed by ADHD is in order, sufficient evidence exists to warrant focus on possible treatments that may serve to improve these driving problems and reduce the risk for these adverse outcomes. High on the list of such treatments deserving further research and clinical attention is the use of stimulant medication. The more recent noradrenergic reuptake inhibitor. atomoxetine, also may have some promise in this regard. Studies are underway in the author's driving laboratory to see if this is the case. Meanwhile, adults with ADHD and parents of teens with ADHD should be advised about these heightened risks and encouraged to take steps that may reduce them, including the consideration of more graduated licensing for adolescents with ADHD and the possible use of stimulant medication in teens and adults with ADHD while they are operating a motor vehicle.     

Brain function and structure in adults with attention-deficit/hyperactivity disorder.

Cross-sectional data suggest that brain dysfunctions are a central component of attention-deficit/hyperactivity disorder (ADHD) in children, and a growing literature is suggesting the same for adults.This article reviews the current state of the literature pertaining to the structural and functional brain abnormalities that are found in adults with ADHD. Because the literature on ADHD in children is more extensive than that reported heretofore in ADHD in adults,the authors include brief summaries of the child literature to help inform that found in adults.     

Set shifting and working memory in adults with attention-deficit/hyperactivity disorder

Compared to the high number of studies that investigated executive functions (EF) in children with attention-deficit/hyperactivity disorder (ADHD), a little is known about the EF performance of adults with ADHD. This study compared 37 adults with ADHD (ADHD_total) and 32 control participants who were equivalent in age, intelligence quotient (IQ), sex, and years of education, in two domains of EF—set shifting and working memory. Additionally, the ADHD_total group was subdivided into two subgroups: ADHD patients without comorbidity (ADHD⁻, n = 19) and patients with at least one comorbid disorder (ADHD⁺, n = 18). Participants fulfilled two measures for set shifting (i.e., the trail making test, TMT and a computerized card sorting test, CKV) and one measure for working memory (i.e., digit span test, DS). Compared to the control group the ADHD_total group displayed deficits in set shifting and working memory. The differences between the groups were of medium-to-large effect size (TMT: d = 0.48; DS: d = 0.51; CKV: d = 0.74). The subgroup comparison of the ADHD⁺ group and the ADHD⁻ group revealed a poorer performance in general information processing speed for the ADHD⁺ group. With regard to set shifting and working memory, no significant differences could be found between the two subgroups. These results suggest that the deficits of the ADHD_total group are attributable to ADHD rather than to comorbidity. An influence of comorbidity, however, could not be completely ruled out as there was a trend of a poorer performance in the ADHD⁺ group on some of the outcome measures.