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PubMed2001

A comparison of the neuropsychological profiles of the DSM-IV subtypes of ADHD.

Recent research on the DSM-IV subtypes of attention-deficit/hyperactivity disorder (ADHD) has demonstrated that the subtypes differ in demographic characteristics, types of functional impairment, and profiles of comorbidity with other childhood disorders. However, little research has tested whether the subtypes differ in underlying neuropsychological deficits. This study compared the neuropsychological profiles of children without ADHD (n = 82) and children who met symptom criteria for DSM-IV Predominantly Inattentive subtype (ADHD-IA; n = 67), Predominantly Hyperactive Impulsive subtype (ADHD-HI; n = 14), and Combined subtype (ADHD-C; n = 33) in the areas of processing speed, vigilance, and inhibition. We hypothesized that children with elevations of inattention symptoms (ADHD-IA and ADHD-C) would be impaired on measures of vigilance and processing speed, whereas children with significant hyperactivity/impulsivity (ADHD-HI and ADHD-C) would be impaired on measures of inhibition. Contrary to prediction, symptoms of inattention best predicted performance on all dependent measures, and ADHD-IA and ADHD-C children had similar profiles of impairment. In contrast, children with ADHD-HI were not significantly impaired on any dependent measures once subclinical symptoms of inattention were controlled. Our results do not support distinct neuropsychological deficits in ADHD-IA and ADHD-C children, and suggest that symptoms of inattention, rather than symptoms of hyperactivity/impulsivity, are associated with neuropsychological impairment.

Adolescent↗

PubMed2000

Age-sensitive cognitive function, growth hormone and insulin-like growth factor 1 plasma levels in healthy older men.

Circulating levels of growth hormone (GH) change during the process of aging. Decline of cognitive functioning with aging is also well established. In this study, we investigated whether insulin-like growth factor 1 (IGF-1) and the GH response to a challenge of GH-releasing hormone and GH-releasing peptide 6 were associated with age-sensitive cognitive functions, but not with functions that do not decline with aging, in 17 healthy male subjects aged between 66 and 76 years. In addition, relations with anthropometric measures were examined. Neuropsychological performance was scored on tests of variables not sensitive to aging (general knowledge, vocabulary, basic visual perception and reading ability), and of variables sensitive to aging (visuoconstructive ability, perceptual motor and mental processing speed, and verbal long-term memory). After correcting for education, the serum GH response was significantly associated with two age-sensitive cognitive tests (measures of mental processing speed), but with none of the tests not sensitive to aging. However, the direction of the association was opposite to the relation between IGF-1 and these cognitive tests: higher levels of GH response were associated with poorer cognitive performance, whereas higher levels of IGF-1 were associated with better performance. GH response, but not IGF-1, was inversely correlated with body mass index. The results are in accordance with previous research suggesting a disruption of the relation between IGF-1 and GH secretion in older age.

Aged↗

PubMed2006

Diffusion tensor imaging of the corpus callosum in Autism.

The corpus callosum is the largest commissural white matter pathway that connects the hemispheres of the human brain. In this study, diffusion tensor imaging (DTI) was performed on subject groups with high-functioning autism and controls matched for age, handedness, IQ, and head size. DTI and volumetric measurements of the total corpus callosum and subregions (genu, body and splenium) were made and compared between groups. The results showed that there were significant differences in volume, fractional anisotropy, mean diffusivity, and radial diffusivity between groups. These group differences appeared to be driven by a subgroup of the autism group that had small corpus callosum volumes, high mean diffusivity, low anisotropy, and increased radial diffusivity. This subgroup had significantly lower performance IQ measures than either the other individuals with autism or the control subjects. Measurements of radial diffusivity also appeared to be correlated with processing speed measured during the performance IQ tests. The subgroup of autism subjects with high mean diffusivity and low fractional anisotropy appeared to cluster with the highest radial diffusivities and slowest processing speeds. These results suggest that the microstructure of the corpus callosum is affected in autism, which may be related to nonverbal cognitive performance.

Adolescent↗

PubMed2004

Leg extensor power, cognition, and functional performance in independent and marginally dependent older adults.

BACKGROUND: physical and cognitive function must be integrated and optimised in performance of daily activities. Age-related loss of physical function can result in poor performance of necessary daily activities and possibly lead to increased dependency and a change of living status. OBJECTIVES: (1) to evaluate average differences in physiological, cognitive, and functional performance of older adults from two different levels of independence, (2) to examine contributions of leg power, cognition, and functional performance to level of independence. DESIGN: cross-sectional study of self-reported 'independent' versus 'marginally dependent' older adults. SUBJECTS: 35 older adults (77.2 +/- 6 years) were placed into independent (n = 18) or marginally dependent (n = 17) groups based upon the Medical Outcomes Study SF36 physical function scores (independent: SF36PF > or = 85, marginally dependent: SF36PF < 85) and living status. METHODS: assessment of physical function includes the dependent variable, SF36PF. Assessment of physical, cognitive, and functional performance include the independent variables of leg extensor power, reaction time, processing speed, memory, attention, and functional performance. Functional performance is assessed by the Continuous Scale Physical Functional Performance Test. RESULTS: independent older adults have greater performance on leg power, reaction time, processing speed, memory, and functional performance than marginally dependent older adults. Functional performance is an independent predictor of level of independence. Leg power and cognition were separate small but significant predictors of independence. CONCLUSIONS: independent older adults have greater physiological, cognitive and functional performance than marginally dependent older adults. Individuals with greater functional performance tend to remain independent.

Activities of Daily Living↗

PubMed2004

General slowing or decreased inhibition? Mathematical models of age differences in cognitive functioning.

Researchers have attempted to explain age-related decrements in cognitive performance in terms of reduced processing speed or decreased ability to inhibit irrelevant thoughts. We present these ideas in the context of a dynamic model derived from extensions of the classical predator-prey equation. Reduced processing speed among older adults is represented by use of delays in the dynamic model, whereas the interference imposed by distractors is captured by use of the predator-prey interaction term. We demonstrate the versatility of this modeling approach, and its pertinence to age-related behavioral change, by means of numerical simulations. In showing the applicability of these models, we identify several unresolved methodological and measurement issues that have to be addressed.

Aged↗

PubMed1995

Cognitive mediation of adult age differences in language performance.

Young (M = 20 years) and old (M = 68 years) adults completed language processing tasks, measures of working memory capacity (backward span and the n-back lag task), inhibitory efficiency (Stroop interference), and processing speed (color naming). regression analyses revealed that each of the resource measures significantly predicted language performance and attenuated variance in language performance that would otherwise be attributed to age. When speed variance was entered into the equation first, the mediating influence of the inhibition and working memory measures remained significant. When speed and inhibition differences were controlled, the working memory measures could not reliably predict language performance. These results suggest that language performance differences may be fundamentally mediated by age differences in processing speed and inhibitory efficiency.

Adolescent↗

PubMed2002

Older age, traumatic brain injury, and cognitive slowing: some convergent and divergent findings.

Reaction time (RT) meta-analyses of cognitive slowing indicate that all stages of processing slow equivalently and task independently among both older adults (J. Cerella & S. Hale, 1994) and adults who have suffered a traumatic brain injury (TBI; F. R. Ferraro, 1996). However, meta-analyses using both RT and P300 latency have revealed stage-specific and task-dependent changes among older individuals (T. R. Bashore, K. R. Ridderinkhof, & M. W. van der Molen, 1998). Presented in this article are a meta-analysis of the effect of TBI on processing speed, assessed using P300 latency and RT, and a qualitative review of the literature. They suggest that TBI induces differential slowing. Similarities in the effects of older age and TBI on processing speed are discussed and suggestions for future research on TBI-induced cognitive slowing are offered.

Adult↗

PubMed2006

Spatial and non-spatial attention deficits in neurodegenerative diseases: assessment based on Bundesen's theory of visual attention (TVA).

PURPOSE: The aim was to present evidence that, similarly as in neglect, a combined pattern of spatial and non-spatial deficits of visual attention can also be typically observed in patients suffering from neurodegenerative disorders. METHOD: Whole and partial report of brief letter arrays, based on Bundesen's 'theory of visual attention' (TVA), was applied in patients suffering from Huntington's disease (HD), mild cognitive impairment (MCI), or Alzheimer's disease (AD). TVA-based parameter estimates were derived reflecting (a) perceptual processing speed and visual working memory storage capacity as non-spatial aspects of visual attention (determined by whole report performance), and (b) spatial attentional weighting (determined by partial report performance). RESULTS: Processing speed was severely slowed in HD, and also reduced, although to a lesser degree, in MCI and AD patients. In HD and AD patients, but not in MCI patients, a strong leftward bias of spatial attention was observed. CONCLUSION: Neglect and neurodegenerative diseases both involve a similar constellation of non-spatial and spatial deficits of visual attention. Therefore, by using TVA-based measurement, results from both fields of research may fruitfully inform each other in future studies, thus improving our understanding of the interaction of spatial and non-spatial attention deficits and its behavioral consequences.

Aged↗

PubMed1995

Neuropsychological impairments in chronic fatigue syndrome, multiple sclerosis, and depression.

To examine the degree and nature of cognitive impairments in chronic fatigue syndrome, a comprehensive neuropsychological battery was given to patients with chronic fatigue syndrome, multiple sclerosis, depressed patients, and healthy controls. The battery included tests of attention and concentration, information processing speed, verbal and visual memory, intellectual ability, and concept formation. Measures of depression and anxiety were also obtained. The chronic fatigue syndrome group did not differ from the depressed group in overall neuropsychological performance, but differed from the multiple sclerosis and control groups. The most significant impairment was in information processing speed in the chronic fatigue syndrome group. Depression and anxiety were not related to neuropsychological performance. The influence of reduced information processing on other areas of cognition is discussed.

Adult↗

PubMed2002

Cognitive functioning and quality of life in long-term adult survivors of bone marrow transplantation.

BACKGROUND: The late neurotoxic effects of bone marrow transplantation (BMT) on cognitive functioning and quality of life (QOL) were investigated in a consecutively treated cohort of long-term adult survivors. METHODS: Progression-free patients treated with BMT or peripheral stem cell grafts for a hematologic malignancy at least 2 years before study participation were examined with a comprehensive battery of neuropsychological tests and questionnaires for QOL and mood states. The results of the neuropsychological tests were compared with healthy population norms. RESULTS: Forty patients were included, 87.5% of whom had undergone an allogeneic transplantation. All received total body irradiation up to 12 Gy (in two fractions). Assessment took place 22-82 months after BMT. Mild to moderate cognitive impairment was found in 24 patients (60%). Compared with healthy population norms, selective attention and executive function, information processing speed, verbal learning, and verbal and visual memory were most likely to be affected. The mean score for the total patient group revealed that these patients scored significantly lower on the information processing speed task compared with expected scores obtained from the normal population. The main predictors for poor neuropsychological performance were fatigue, global health, and educational level. Other correlations with moderate to severe cognitive impairment were subjective cognitive complaints, physical functioning, social functioning, overall mood states, and employment status. CONCLUSIONS: These data indicate that BMT may lead to cognitive complaints and late cognitive deficits in long-term adult survivors. Cognitive functioning should therefore be used as an outcome parameter in BMT studies.

Adolescent↗

PubMedDate not supplied

Sequencing versus nonsequencing working memory in understanding of rapid speech by older listeners.

The goal of this study was to identify specific neurocognitive deficits that are associated with older listeners' difficulty understanding rapid speech. Older listeners performed speech recognition tests comprised of time-compressed sentences with and without context, and on a neurocognitive battery aimed specifically at testing working memory, processing speed, and attention. A principle component analysis identified three main cognitive components as follows: a sequencing working memory (WM-S) component, a nonsequencing working memory (WM-NS) component, and a processing speed (PS) component. Each of the cognitive component scores was divided into high, mid, and low categories. Sentence performance of the cognitive subgroups was compared within each component. The results showed that, with hearing loss and age accounted for, the cognitive score groups differed similarly on the sentence condition scores also at 50 and 60% time compression, particularly on the subgroups of the WM-S component. The results suggest that deficits in a separate working memory function identified as sequencing were associated with differences in ability to understand time-compressed speech in this study.

Age Factors↗

PubMed2004

Neuropsychological and information processing performance and its relationship to white matter changes following moderate and severe traumatic brain injury: a preliminary study.

Reductions in information processing speed have frequently been reported following moderate and severe traumatic brain injuries (TBIs), consistent with the effects of diffuse white matter damage. Although the corpus callosum (CC) is a common site for diffuse damage following TBI, the effects of this damage on information processing speed have not been adequately examined. This study assessed a TBI group and a matched control group on tests of attention, memory, fluency, and set shifting ability, together with reaction time (RT) tasks requiring the inter- and intrahemispheric processing of visual and tactile information. The RT tasks were designed to target the cognitive functions that are likely to be affected by diffuse white matter damage, including damage to the CC. The TBI group demonstrated deficits in verbal and visual fluency and verbal memory. They were also slower on the visual and tactile RT tasks, were more affected by task complexity, and slower on RT tasks requiring the interhemispheric transfer of information. In fact, one of the interhemispheric tactile RT tasks proved to be the most discriminating of all the cognitive and RT measures. MRIs completed on a subset of TBI participants indicated that the mean CC measurements were 5% to 19% smaller than a normative control group, with the most atrophied areas being the isthmus and anterior midbody. Although white matter atrophy was moderately related to visual and tactile RT performance, and total hippocampal volume related to memory performance, CC area was not related to many of the tasks that were designed to tap interhemispheric processing. None of the standard cognitive tests correlated with outcome in the TBI group, but 1 of the tactile RT measures was significantly related to 2 measures of outcome.

Adolescent↗

PubMed2006

Ankle brachial index as a predictor of cognitive impairment in the general population: ten-year follow-up of the Edinburgh Artery Study.

OBJECTIVES: To determine whether the ankle brachial index (ABI, a marker of generalized atherosclerosis) is associated with cognitive impairment after 10 years in older people. DESIGN: Cohort study (Edinburgh Artery Study). SETTING: Eleven general practices in Edinburgh, Scotland. PARTICIPANTS: Seven hundred seventeen men and women aged 55 to 74 from the general population, followed for 10 years. MEASUREMENTS: ABI measured at baseline and major cognitive functions (including premorbid function using the National Adult Reading Test, NART) tested after 10 years. RESULTS: After adjustment for age and sex, a low ABI was associated with lower scoring (bottom tertile vs top tertile) on Raven's Matrices (odds ratio (OR)=1.6, 95% confidence interval (CI) =1.0-2.6), Verbal Fluency (OR =1.8, 95% CI =1.1-3.0), and Digit Symbol Test (OR =2.3, 95% CI =1.3-4.2), suggesting that the ABI is predictive of poorer performance in nonverbal reasoning, verbal fluency, and information processing speed. The association between ABI and the Digit Symbol Test remained significant after further adjustment for premorbid cognitive function (tested using the NART), suggesting that the ABI is also predictive of decline in information processing speed (from premorbid ability to that measured here in older age). CONCLUSION: The ABI may be useful in identifying older individuals at higher risk of cognitive impairment. In the future, preventive measures developed to target individuals with a low ABI should consider measures to reduce vascular-related cognitive decline as well as cardiovascular events, in an effort to reduce the incidence and consequences of subsequent cognitive impairment and dementia.

Aged↗

PubMed2004

Cognitive enhancement therapy for schizophrenia: effects of a 2-year randomized trial on cognition and behavior.

BACKGROUND: Deficits in social cognition and neurocognition are believed to underlie schizophrenia disability. Attempts at rehabilitation have had circumscribed effects on cognition, without concurrent improvement in broad aspects of behavior and adjustment. OBJECTIVE: To determine the differential effects of cognitive enhancement therapy (a recovery-phase intervention) on cognition and behavior compared with state-of-the-art enriched supportive therapy. DESIGN: A 2-year, randomized controlled trial with neuropsychological and behavioral assessments completed at baseline and at 12 and 24 months. SETTING: An outpatient research clinic housed in a medical center's comprehensive care service for patients with severe mental illness. PATIENTS: A total of 121 symptomatically stable, non-substance-abusing but cognitively disabled and chronically ill patients with schizophrenia or schizoaffective disorder. INTERVENTIONS: Cognitive enhancement therapy is a multidimensional, developmental approach that integrates computer-assisted training in neurocognition with social cognitive group exercises. Enriched supportive therapy fosters illness management through applied coping strategies and education. MAIN OUTCOME MEASURES: Six highly reliable summary measures--Processing Speed, Neurocognition, Cognitive Style, Social Cognition, Social Adjustment and Symptoms--were tested using analysis of covariance and linear trend analysis. RESULTS: At 12 months, robust cognitive enhancement therapy effects were observed on the Neurocognition and Processing Speed composites (P<.003), with marginal effects observed on the behavioral composites. By 24 months, differential cognitive enhancement therapy effects were again observed for the 2 neuropsychological composites and for Cognitive Style (P=.001), Social Cognition (P=.001), and Social Adjustment (P=.01). As expected, no differences were observed on the residual Symptoms composite. Effects were unrelated to the type of antipsychotic medication received. Enriched supportive therapy also demonstrated statistically significant within-group effect sizes, suggesting that supportive psychotherapy can also have positive, although more modest, effects on cognitive deficits. CONCLUSION: Many cognitive deficits and related behaviors of patients with stable schizophrenia are improved when sufficient exposure to relevant rehabilitation is provided.

Adult↗

PubMed2003

Speed of information processing after unilateral stroke.

Speed of information processing in the subacute stage after stroke was studied in 88 first ever, unilateral, ischemic stroke patients. The patient group included 42 right and 46 left hemisphere patients. Seventy-one control subjects were also examined. Four reaction time tasks with different levels of complexity were used: two visuomotor, and two semantic categorisation tasks. The results showed that stroke causes a decrease in decision making speed, but that the effect is different for right and left hemisphere patients. The right hemisphere group were slower than the control group on all reaction time tasks, and slower than the left hemisphere patients on the visuomotor tasks. The left hemisphere patients were slower than the healthy controls, only on the most complex tasks, the categorisation tasks.

Adult↗

PubMed2006

The relationship of working memory, inhibition, and response variability in child psychopathology.

INTRODUCTION: The aim of this study was to investigate the relationship between working memory and inhibition in children with attention deficit hyperactivity disorder (ADHD), high-functioning autism (HFA), and Tourette syndrome (TS), compared to normally developing children. Furthermore, the contribution of variation in processing speed on working memory and inhibition was investigated in these childhood psychopathologies. METHOD: Four groups of children are reported in this study: 65 children with ADHD, 66 children with HFA, 24 children with TS, and 82 normal control children. All children were in the age range of 6-13 years. RESULTS: The relationship between working memory and inhibition was similar in children with ADHD, HFA, TS, and normally developing children. The relationship between both domains did not alter significantly for any of the groups, when variation in processing speed was taken into account. More symptoms of hyperactivity/impulsivity are related to a poorer inhibitory process and greater response variability. More symptoms of autism are related to a poorer working memory process. CONCLUSION: The current study showed that working memory, inhibition, and response variability, are distinct, but related cognitive domains in children with developmental psychopathologies. Research with experimental manipulations is needed to tackle the exact relationship between these cognitive domains.

Adolescent↗

PubMed1999

Speech-reading: cognitive predictors and displayed emotion.

The present study had three aims: to examine the effects of displayed emotion and message length on speech-reading performance, and how measures of working memory (cf. Baddeley 1986) and verbal information processing speed relate to speech-reading performance. Words and sentences with either positive or negative meaning were used in a word decoding and a sentence-based speech-reading test. A total of 48 normal-hearing subjects participated. The results revealed general effects of displayed emotion, message meaning and message length and no effect of displayed emotion vs message length. Furthermore, working memory but not verbal information processing speed nor accuracy predicted speech-reading performance. The results were discussed with respect to a model of face-processing (Bruce & Young 1986) and with respect to clinical implications.

Adult↗

PubMed2004

Neurocognitive consequences of marihuana--a comparison with pre-drug performance.

In determining the effects of regular marihuana use on neurocognition, abilities within specific relevant cognitive domains prior to regular drug use have not been available. The present study examined effects of current and past regular use of marihuana in subjects for whom pre-drug performance had been ascertained in a prospective, longitudinal fashion. A total of 113 young adults, assessed since infancy, were evaluated using neurocognitive tests for which commensurate measures were obtained prior to the initiation of marihuana smoking. Marihuana users, determined by urinalysis and self-report, were categorized as light (< 5 joints per week) and heavy (> or = 5 joints per week) current users and former users, the latter having used the drug regularly in the past (> or = 1 joint per week) but not for at least 3 months. A third of the subjects were using marihuana on a regular basis at the time of assessment with half being heavy users. Among former, regular users, approximately half had been smoking 5 or more joints per week. Overall IQ, memory, processing speed, vocabulary, attention, and abstract reasoning were assessed. After accounting for potentially confounding factors and pre-drug performance in the appropriate cognitive domain, current regular heavy users did significantly worse than non-users in overall IQ, processing speed, immediate, and delayed memory. In contrast, the former marihuana smokers did not show any cognitive impairments. It was concluded that residual marihuana effects are evident beyond the acute intoxication period in current heavy users after taking into account pre-drug performance but similar deficits are no longer apparent 3 months after cessation of regular use, even among former heavy using young adults.

Adult↗