Adults with ADHD. An overview.

Attention-Deficit Hyperactivity Disorder (ADHD) is a common, genetically transmitted neurological disorder, with onset in childhood, probably mediated by decreased brain dopaminergic functioning. The first author was one of the earliest to describe the persistence of symptoms into adulthood. Prevalence and natural history data suggest that of the 3 to 10% of children diagnosed with ADHD, one- to two-thirds (somewhere between 1 and 6% of the general population) continue to manifest appreciable ADHD symptoms into adult life. This paper describes how ADHD in adults can be readily diagnosed and treated, despite resembling or coexisting with other psychiatric disorders. The Wender Utah diagnostic criteria address adult characteristics of the disorder. Informant and patient interviews and rating scales are used to determine the psychiatric status of the patient as a child, make a retroactive diagnosis of childhood ADHD, and establish the current diagnosis of the adult. Stringent diagnosis is key to determining effective treatment. Dopamine agonist stimulant medications appear to be the most effective in treating ADHD. About 60% of patients receiving stimulant medication showed moderate-to-marked improvement, as compared with 10% of those receiving placebo. The core symptoms of hyperactivity, inattention, mood lability, temper, disorganization, stress sensitivity, and impulsivity have been shown to respond to treatment with stimulant medications. Non-dopaminergic medications, such as the tricyclic antidepressants and SSRIs have generally not been useful in adults with ADHD in the absence of depression or dysthymia. Pemoline is no longer approved for use in these patients, despite early favorable reports. Appropriate management of adult patients with ADHD is multimodal. Psychoeducation, counseling, supportive problem-directed therapy, behavioral intervention, coaching, cognitive remediation, and couples and family therapy are useful adjuncts to medication management. Concurrent supportive psychosocial treatment or polypharmacy may be useful in treating the adult with comorbid ADHD.

Attention deficit/hyperactivity disorder as a right hemisphere syndrome. Selective literature review and detailed neuropsychological case studies.

Recent studies of ADHD implicate well-defined neuroanatomical networks and neurochemical pathways in its pathophysiological basis. Considerable attention has focused on the role of anterior and superior frontal regions and portions of the basal ganglia, including the caudate nucleus and globus pallidus. This paper reviews a growing literature suggesting differential involvement of right hemisphere mechanisms specialized for behavioral regulation and attention. Supportive data are drawn from neuropsychology, neuroanatomy, and neurochemistry. In addition, three cases are presented that illustrate the complex role of right hemisphere dysfunction in adult manifestations of ADHD. We suggest that the pleomorphic presentations of ADHD can be understood in terms of a spectrum of disturbances in overlapping neural regions, especially involving frontal and parietal areas of the right hemisphere and their connections to subcortical structures (including the striatum, limbic system and diencephalic nuclei).

Metacognitive remediation in adult ADHD. Treating executive function deficits via executive functions.

The neuropathology underlying ADHD most consistently points to dysfunction in corticostriatal pathways--leading to inactivation, or insufficient engagement, of frontal and prefrontal lobes. By implication there may be functional disconnection between the anterior and posterior higher cortical regions, instead of a fixed dysfunction in either one. Given this premise, reconnection of these systems via cognitive interventions constitutes a logical remedial approach in the treatment of ADHD, which this paper introduces. In particular, a hybrid model is developed which proposes integration of existing psychodynamic, cognitive, and neuropsychological interventions. An organizing theme is expansion of metacognitive understanding through these procedures, powerfully exemplified via use of metaphor in clinical vignettes.

Adult ADHD. Concluding thoughts.

This concluding paper raises some final questions and issues that the authors feel should receive more emphasis in future research on ADHD in adults. One significant problem for our field is the upward extension of child-based models and approaches without proper adaptation to adults. With adults differing patterns of comorbidity and symptom heterogeneity pose new conceptual, diagnostic, and treatment challenges. As an illustration, we review ten common presenting complaints in adults and their link to the underlying core ADHD deficits of hyperkinesis, inattention, and impulsivity. While these core symptoms are often overt problems in children, in adults subtler executive dysfunction appears. Even though the growing consensus is that ADHD is a disorder of executive functions (EF), the details of the EF/ADHD connection remain unclear and may be far more complex in adults. That complexity is mirrored in the widening anatomic representation of EF, extending beyond the frontal lobes into the subcortex and other nonfrontal regions. More research will be needed to follow the developmental trajectory of executive dysfunction in ADHD over the life cycle and tie this to the developmental neuropsychology of EF. Psychosocial context and nongenetic familial influence are also critical variables that need greater consideration when characterizing and measuring ADHD symptoms in adults. Finally, until we have reached consensus on adult subject selection, we may not be able to enhance diagnostic rigor or expand our conceptual framework for understanding the underlying pathophysiology of ADHD in adults.

Visuospatial orientation in Parkinson's disease.

Visuospatial functioning in patients with Parkinson's disease was investigated using neuropsychological measures of basic visual perception, complex perceptual discrimination, and spatial orientation. Three subgroups of patients were described: (a) those with broadly impaired visuospatial abilities, (b) those with generally intact abilities, and (c) those whose performance on a task of spatial orientation was lower than their performance on a task of complex perceptual discrimination. These subgroup differences were also concordant with three other variables: age, duration of disease, and degree of dementia. It is suggested that decreases in spatial orientation functioning in Parkinson's disease may reflect the speed of progression of this disease.

Retrograde amnesia following unilateral temporal lobectomy.

Remote memory performance was assessed in a carefully matched sample of temporal lobectomy subjects and normal controls. Left temporal lobectomy subjects exhibited a consistent pattern of remote memory disturbance. Right temporal lobectomy subjects performed at the same level as normal controls. The pattern of impairment observed in left temporal lobectomy subjects was characterized by deficits in recall of chronological information from the past decade and extended to deficits in recall in some aspects of factual knowledge. The disorder could not be attributed solely to language deficits and was at least as severe as accompanying deficits in recent memory. These findings suggest that the left medial temporal region may play a significant role in recall of remote information in addition to its role in recent memory functions.

Regional distribution of cerebral arteriovenous malformations. Interactions with sex and handedness.

On the basis of clinical observation and a developmental theory of cerebral laterality, Geschwind and Galaburda suggested that cerebral arteriovenous malformations (AVMs) are more common in the left hemispheres of male patients. We tested this hypothesis by examining interactions among sex, handedness, and location of lateralized, supratentorial AVMs. Data from 112 cases were analyzed by log-linear procedures. We found that (1) females had a greater proportion of left-hemisphere AVMs, whereas males showed an opposite trend; (2) there were no interactions between sex and handedness; and (3) nondextrals showed a higher proportion of AVMs located in frontal regions, regardless of the hemispheric side of the lesion. Although these findings appear to be inconsistent with the Geschwind-Galaburda hypothesis, the inconsistency may be attributable to the embryonic stage at which this developmental abnormality occurs. In addition, the unexpected findings may also reflect our use of multivariate statistical procedures, which control for interaction effects.

Unilateral displacement in the olfactory sense: a manifestation of the unilateral neglect syndrome.

Unilateral neglect is a syndrome primarily occurring with right hemisphere--particularly right parietal lobe--brain damage and involving the failure to respond to stimuli presented to the left side of the body and space. Unilateral displacement (a less severe manifestation of the neglect syndrome) involves the accurate identification of a stimulus, but the displacement or mislocalization of that stimulus to the opposite side of the body and space. This study investigated two major theories of unilateral neglect utilizing the primarily ipsilaterally innervated olfactory sense. The sensory theory states that unilateral neglect is due to a diminished sensory input, whereas the representational theory states that it is due to a disordered internal representation which is not dependent on sensory input. Results revealed that right hemisphere lesion patients with left unilateral neglect exhibited a significantly greater number of displacements in their left nostril on olfactory double simultaneous stimulation, consistent with the representational theory.

The nature of unilateral neglect in the olfactory sensory system.

This study investigated two major theories of unilateral neglect utilizing the ipsilaterally innervated olfactory sense. The sensory theory states that unilateral neglect is due to a diminished or attenuated sensory input. The representational theory states that unilateral neglect is due to a disordered internal representation, which is not dependent on sensory input. Results of the study revealed that right hemisphere lesion patients with left unilateral neglect failed to respond to their left contralateral nostril on olfactory double simultaneous stimulation, consistent with the representational theory because the left nostril has no direct sensory input to the right hemisphere.

In search of closure: subjective contour illusions, Gestalt completion tests, and implications.

This study investigates the construct validity of perceptual closure tests (CTs), and isolates a common processing demand from the right-hemisphere. Sixty-seven patients with focal unilateral lesions (34 right side, 33 left side), and 80 control subjects participated. Multivariate analyses indicated that there was substantial age-related variance in all CTs, while sex was variably significant; CTs are not uniform in their discriminating ability, and hence factorially complex; and their specifically right hemisphere-sensitive dimension was subjective contour illusions, and interestingly unrelated to facial discrimination ability. The methodological and theoretical implications are discussed.

Evidence for differentiation of right hemisphere visual-perceptual functions.

Performance on tasks sensitive to right hemisphere dysfunction (facial discrimination and perceptual closure) are reported in eight patients with right hemisphere lesions. Patients demonstrated an apparent double dissociation of performance on the two measures. Site-by-task specificity for the closure task was strongly suggested. Implications for right hemisphere organization and underlying psychological processes are considered.