Biomedical subjects

Robert K Heaton

Publications and source records attributed to Robert K Heaton.

At least 19 recordsLinked to original sources

PubMed2007

Incident major depression does not affect neuropsychological functioning in HIV-infected men.

The diagnosis of lifetime major depressive disorders (MDDs) and of current major depressive episodes (MDEs) are relatively common in HIV-infected individuals, and often are assumed to influence neuropsychological (NP) performance. Although cross-sectional studies of HIV-infected individuals generally have found no systematic link between current MDE or depressive symptoms and NP performance, longitudinal studies are needed to clarify whether incident MDE may impact NP functioning in at least some cases. Two hundred twenty-seven human immunodeficiency virus (HIV)-infected adult men, who did not meet criteria for a current MDE at baseline, participated in a longitudinal NP study for an average of two years. Participants received repeated NP assessments, as well as structured psychiatric interviews to ascertain presence or absence of both lifetime MDD and current MDE. Ninety-eight participants had a lifetime history of MDD, and 23 participants met criteria for incident MDE at one of their follow-up evaluations. Groups with and without lifetime MDD and/or incident MDE had comparable demographics, HIV disease status and treatment histories at baseline, and numbers of intervening assessments between baseline and the final follow-up. Lifetime MDD was associated with greater complaints of cognitive difficulties in everyday life, and such complaints were increased at the times of incident MDE. However, detailed group comparisons revealed no NP performance differences in association with either lifetime or incident major depression. Finally, NP data from consistently nondepressed participants were used to develop "norms for change" and these findings failed to show any increased rates of NP worsening among individuals with incident MDE. Our results suggest that neurocognitive impairment and major depression should be considered as two independent processes.

Adult↗

PubMed2006

Correlations of functional capacity and neuropsychological performance in older patients with schizophrenia: evidence for specificity of relationships?

BACKGROUND: Neuropsychological (NP) performance is a consistent correlate of everyday functioning in schizophrenia, but it is unclear whether relationships between individual NP ability areas and domains of everyday functioning are general or specific. Assessments of real-world everyday functioning may be influenced by environmental and social factors (e.g., social security, disability status, opportunities and restrictions in living situations). This study examined the specificity of the relationships between different NP abilities and performance-based measures of social and living skills. METHODS: 181 ambulatory older (age>50) patients with schizophrenia were examined with NP tests measuring episodic and working memory, executive functioning, verbal fluency, and processing speed. All subjects performed tasks examining social (Social Skills Performance Assessment: SSPA) and everyday living (UCSD Performance Based Skills Assessment: UPSA) skills. RESULTS: Using canonical analysis, the NP variables were used to predict the functional capacity measures. The analysis found that 37% of the variance in the functional capacity and NP measures was shared, X(2) (54)=106.29, p<.001. Two canonical roots described the cognitive variables and the roots were differentially associated with everyday living and social skills. The root loading on processing speed, episodic memory, and executive functions were associated with UPSA scores, while the root loading on working and episodic memory and verbal fluency were associated most strongly with social competence. IMPLICATIONS: Social and everyday living skills deficits in patients with schizophrenia may reflect generally independent domains of functional outcome, linked through cognitive performance. The data suggest that somewhat different cognitive processes are associated with these two domains of functional capacity, although there appears to be some overlap, which may be due to the nature of the NP tests employed.

Activities of Daily Living↗

PubMed2006

Assessment of community functioning in people with schizophrenia and other severe mental illnesses: a white paper based on an NIMH-sponsored workshop.

People with schizophrenia frequently have significant problems in community functioning. Progress in developing effective interventions to ameliorate these problems has been slowed by the absence of reliable and valid measures that are suitable for use in clinical trials. The National Institute of Mental Health convened a workgroup in September 2005 to examine this issue and make recommendations to the field that would foster research in this area. This article reports on issues raised at the meeting. Many instruments have been developed to assess community functioning, but overall insufficient attention has been paid to psychometric issues and many instruments are not suitable for use in clinical trials. Consumer self-report, informant report, ratings by clinicians and trained raters, and behavioral assessment all can provide useful and valid information in some circumstances and may be practical for use in clinical trials. However, insufficient attention has been paid to when and how different forms of assessment and sources of information are useful or how to understand inconsistencies. A major limiting factor in development of reliable and valid instruments is failure to develop a suitable model of functioning and its primary mediators and moderators. Several examples that can guide thinking are presented. Finally, the field is limited by the absence of an objective gold standard of community functioning. Hence, outcomes must be evaluated in part by "clinical significance." This criterion is problematic because different observers and constituencies often have different opinions about what types of change are clinically important and how much change is significant.

Activities of Daily Living↗

PubMed2006

Depression and suicidality in HIV/AIDS in China.

BACKGROUND: This pilot study examined rates of major depression and suicidality and their associations with daily functioning in HIV infected (HIV+) and uninfected (HIV-) persons in China. METHOD: HIV+ participants (N=28) and demographically matched HIV- controls (N=23) completed the Chinese Composite International Diagnostic Interview to determine lifetime rates of major depressive disorder (MDD) and suicidality. Current mood and suicidal ideation were assessed with the Beck Depression Inventory-I. The impact of depression and HIV infection on daily functioning was measured by an Activity of Daily Living questionnaire. RESULTS: Mean duration of known HIV+ status was 2 years. Almost 79% (n=22) of HIV+ but just 4% (n=1) of HIV- groups reported lifetime major depression. Of the 22 HIV+ individuals with lifetime MDD, only one had onset before learning of HIV status. The remainder developed MDD within 6 months after testing HIV positive. In those HIV+ subjects who met MDD criteria after HIV diagnosis, only two (9%) had received depression treatment, yet four (18%) had persisting active suicidal thoughts. Depression and HIV+ status independently predicted worse daily functioning. LIMITATIONS: Representativeness is limited in this small sample of convenience. CONCLUSION: This preliminary study presents evidence of high rates of major depression and suicidality in HIV-infected persons in China. Despite this, few had sought mental health assistance, suggesting a need to increase awareness of psychiatric comorbidity and access to mental health services.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Transient and executive function working memory in schizophrenia.

Transient working memory requires attention and temporary storage of information, whereas executive function working memory requires additional mental manipulation of that information. Working memory impairment is common in schizophrenia patients, but only some studies have found differential impairment in executive function working memory compared to transient working memory. We measured both types of working memory using the Digit Span forward (DF) and backward (DB) tasks in a large sample of schizophrenia patients (n=267) and normal comparison subjects (n=82); in the patients, we also examined associations between performance on the Digit Span tasks and Letter-Number Sequencing (LNS), a putative executive function working memory test. Compared to healthy subjects, the schizophrenia patients showed impairment in the medium effect size range on both DF (d=-0.55) and DB (d=-0.68). DB scores predicted LNS performance, whereas DF scores did not. Worse negative symptoms were associated with worse performance on DF, DB and LNS. These results do not reflect differential executive function working memory dysfunction in schizophrenia, but appear to support transient and executive function working memory as separable constructs.

Adult↗

PubMed2006

Cortical and subcortical neurodegeneration is associated with HIV neurocognitive impairment.

OBJECTIVE: To determine the association of markers of regional neurodegeneration (ND) at autopsy to degree of neurocognitive impairment in persons with HIV. DESIGN: In a prospectively followed cohort of HIV-infected individuals we examined the relationship between antemortem neuropsychological (NP) abilities and postmortem neuropathological data. METHODS: Twenty-seven HIV-infected individuals with both neuropsychological and neuropathological data were identified. Laser confocal scanning microscopy was used to determine the degree of ND based on: (1) microtubule-associated protein (MAP2; reflecting neuronal cell bodies and dendrites) and (2) synaptophysin (SYN; a measure of presynaptic terminals). A regional combined score, based on the distribution of percentage neuropil occupied by MAP2 and SYN and emphasizing severity of ND, was created for each brain region: midfrontal cortex, hippocampus, and putamen. RESULTS: The regional combined scores from each brain region studied were better correlated with level of global NP impairment than measures of SYN and MAP2 individually. In a regression, hippocampal and putamen regional combined scores were independent predictors of degree of antemortem NP impairment (F(3,23) = 6.17; P < 0.01; R2 = 0.45). The correlations among regional ND measures demonstrated that ND is unevenly distributed across multiple brain regions. CONCLUSIONS: As the anatomic distribution and temporal progression of neuropathologic changes appears to differ across individuals, it is important to consider both cortical and subcortical brain regions in studies of neuropathogenesis and treatment of HIV-related brain disease. Furthermore, combining information from several markers of neural injury provided the strongest association with degree of neurocognitive impairment during life.

Adult↗

PubMed2006

Recency effects in HIV-associated dementia are characterized by deficient encoding.

The aim of the present study was to investigate the nature and cognitive mechanisms of serial position learning effects in HIV-associated dementia (HAD). Participants were 16 persons with HAD, 50 non-demented persons with HIV-infection, and 50 demographically comparable HIV-seronegative participants. HAD participants, relative to both comparison groups, exhibited reduced middle region (p<0.01) and elevated recency region (p<0.05) recall on the Hopkins Verbal Learning Test-Revised, but no primacy region effect (p>0.10). On recognition testing, the HAD group was impaired in discriminating targets from distractors (p<0.01) in all three serial position regions; however, they were not impaired on measures of retrieval (p>0.10) within these same regions. In sum, HAD participants relied disproportionately on recency regions of the list, indicating a passive recall style of echoing only the words within their auditory attention span. Interestingly, HAD participants did not evidence significant improvement on measures of recognition, a finding that suggests that the serial position effects are most consistent with a primary encoding deficit.

AIDS Dementia Complex↗

PubMed2006

An evaluation of longitudinal neurocognitive performance among middle-aged and older schizophrenia patients: use of mixed-model analyses.

The purpose of this study was to evaluate the trajectory of neuropsychological performance among middle-aged and older patients with schizophrenia using hierarchical linear modeling (HLM). Using the Mattis Dementia Rating Scale (DRS), we assessed cognitive performance of 143 schizophrenia outpatients (Mean age=53.1 years, SD=8.8) and 66 healthy comparison subjects (Mean age=61.8 years, SD=8.8). All participants had DRS data from two or more testing sessions with average intervals between sessions being 15 months (range=6-55). Using HLM, we found cognitive performance to be stable over time in both schizophrenia patients and healthy comparison subjects. Age, gender, ethnicity, and education did not affect trajectories. We also analyzed the data using more traditional statistical approaches to longitudinal data and found similar results. In sum, we found cognitive impairment to be stable over time among outpatients with schizophrenia, regardless of the statistical methodology used to analyze longitudinal data.

Adult↗

PubMed2006

Additive deleterious effects of methamphetamine dependence and immunosuppression on neuropsychological functioning in HIV infection.

Methamphetamine (MA) dependence and HIV infection are independently associated with cerebral dysfunction, especially within frontal-basal ganglia circuits. Recent evidence indicates that MA dependence has an additive effect on neuropsychological (NP) deficits associated with HIV infection. This study extends prior findings by examining the combined effects of MA dependence (MA+) and immunosuppression (i.e., CD4 lymphocyte count <200) on NP functioning in 284 HIV+ individuals. Prevalence of NP impairment was examined in four demographically comparable groups: (1) MA+/CD4 < 200; (2) MA+/CD4 > or = 200; (3) MA-/CD4 < 200; and (4) MA-/CD4 > or = 200. Results revealed that both MA dependence and immunosuppression were significant predictors of NP impairment. More importantly, additive effects were evident whereby the MA+/CD4 < 200 group exhibited the highest rate of NP impairment. Findings indicate that MA dependence conveys an additive deleterious impact on NP status in immunosuppressed persons with HIV infection, perhaps reflecting the combined effects of neuropathophysiological mechanisms in fronto-striatal circuits.

Adult↗

PubMed2006

Development of demographic norms for four new WAIS-III/WMS-III indexes.

Following the publication of the third edition Wechsler scales (i.e., WAIS-III and WMS-III), demographically corrected norms were made available in the form of a computerized scoring program (i.e., WAIS-III/WMS-III/WIAT-II Scoring Assistant). These norms correct for age, gender, ethnicity, and education. Since then, four new indexes have been developed: the WAIS-III General Ability Index, the WMS-III Delayed Memory Index, and the two alternate Immediate and Delayed Memory Indexes. The purpose of this study was to develop demographically corrected norms for the four new indexes using the standardization sample and education oversample from the WAIS-III and WMS-III. These norms were developed using the same methodology as the demographically corrected norms made available in the WAIS-III/WMS-III/WIAT-II Scoring Assistant.

Adolescent↗

PubMed2006

Prospective memory in HIV-1 infection.

The cognitive deficits associated with HIV-1 infection are thought to primarily reflect neuropathophysiology within the fronto-striato-thalamo-cortical circuits. Prospective memory (ProM) is a cognitive function that is largely dependent on prefronto-striatal circuits, but has not previously been examined in an HIV-1 sample. A form of episodic memory, ProM involves the complex processes of forming, monitoring, and executing future intentions vis-à-vis ongoing distractions. The current study examined ProM in 42 participants with HIV-1 infection and 29 demographically similar seronegative healthy comparison (HC) subjects. The HIV-1 sample demonstrated deficits in time- and event-based ProM, as well as more frequent 24-hour delay ProM failures and task substitution errors relative to the HC group. In contrast, there were no significant differences in recognition performance, indicating that the HIV-1 group was able to accurately retain and recognize the ProM intention when retrieval demands were minimized. Secondary analyses revealed that ProM performance correlated with validated clinical measures of executive functions, episodic memory (free recall), and verbal working memory, but not with tests of semantic memory, retention, or recognition discrimination. Taken together, these findings indicate that HIV-1 infection is associated with ProM impairment that is primarily driven by a breakdown in the strategic (i.e., executive) aspects of retrieving future intentions, which is consistent with a prefronto-striatal circuit neuropathogenesis.

Adult↗

PubMed2006

Early environmental factors, ethnicity, and adult cognitive test performance.

This study was conducted to better understand cross-cultural variation in neuropsychological test performance by exploring the relationship between early environmental factors and adult neuropsychological functioning in African Americans (AA) and Caucasians (CA). Cognitive testing data and detailed retrospective early environmental histories were obtained from 100 neurologically healthy adults (75 AA, 25 CA). Results indicate that: (a) consistent with previous research, the two ethnic groups differed significantly on their cognitive test performance; (b) early environmental factors were significantly related to performance on cognitive tests; (c) the two ethnic groups demonstrated slight, but significant, differences in their early environmental histories; but (d) covarying early environmental factors did not substantially reduce the group performance in cognitive test performance. The failure of reported environmental factors to account for more of the ethnic disparity in test performance may have resulted from the inherent weakness of the retrospective assessment method (i.e., lack of precision or objectivity in participants' recollections of their early environments). These results highlight the remaining need for ethnicity specific normative data until cross-cultural variation in neuropsychological test performance is better understood.

Adult↗

PubMed2006

Demographically adjusted normative standards for new indices of performance on the Paced Auditory Serial Addition Task (PASAT).

The Paced Auditory Serial Addition Task (PASAT) is a complex cognitive test sensitive to neuropsychological disorders. Its traditional Total Correct score seemingly reflects multiple cognitive abilities, including attention, working memory, and processing speed. Snyder, Aniskiewicz, and Snyder (1993) modified scoring guidelines for the PASAT to give credit only for "dyads." This method emphasizes working memory operations and has been found superior to Total Correct scores at detecting cognitive impairments in several investigations. To date, normative standards are not available for the "dyad" scoring method, thus limiting its utility in clinical and research settings. The current investigation provides demographically adjusted normative data based on a sample of 500 healthy adults of varied age, education, sex, and race (African American and Caucasian) for various indices of performance on the PASAT, including "Total Dyads" obtained across the four PASAT trials. In addition, we describe and present normative data on four other indices designed to quantify various aspects of performance on the PASAT: invalid responding, effects of varied information processing speed demands, and tendency to omit responses and to make arithmetic errors.

Abstracting and Indexing↗

PubMed2006

Work-related abilities in schizophrenia and HIV infection.

Schizophrenia and human immunodeficiency virus (HIV) infection both are associated with high rates of neurocognitive impairment. These impairments predict unemployment in both disorders, independent of other disease-related factors that may affect employment. In this study, we investigated work-related abilities and previous employment patterns in 27 unemployed patients with schizophrenia, 27 demographically matched unemployed HIV-infected participants, and 27 nonmatched employed HIV seropositive (HIV+) participants. All subjects were administered a computerized and hands-on assessment of vocational abilities and a comprehensive work history interview. Compared with the employed HIV+ group, the two unemployed groups had lower estimates of maximal lifetime job functioning. In terms of current vocational abilities, the employed HIV+ subjects generally performed best, followed by the unemployed HIV+ subjects and the patients with schizophrenia. Although the unemployed schizophrenia subjects had the most decline in vocational abilities (from estimated lifetime maximum level), the patterns of decline were similar in the two unemployed groups and were suggestive of parallel impairments in frontal-subcortical functioning.

Adult↗

PubMed2006

Determinants of real-world functional performance in schizophrenia subjects: correlations with cognition, functional capacity, and symptoms.

OBJECTIVE: Impairments in adaptive life skills are a major source of disability in patients with schizophrenia. The relationship between adaptive life skills in real-world settings and performance on neuropsychological tests may be complicated by other factors that interfere with deployment of skills. Assessment of the ability to perform life skills under optimal conditions (i.e., assessment of functional capacity) has been proposed as a means to clarify these relationships. METHOD: The authors examined cross-sectional data from a study of the course of neuropsychological and adaptive life skills of older (age 50-85) schizophrenia patients (N=78). Functional capacity was examined with a performance-based measure (UCSD Performance-Based Skills Assessment), and case managers rated real-world adaptive functions (i.e., interpersonal skills, work skills, and community activities). Neuropsychological performance was assessed with a comprehensive battery, while symptoms were assessed with patient self-report and clinical ratings. RESULTS: Confirmatory path analyses were used to evaluate the effects of neuropsychological performance, functional capacity, and symptoms on the various domains of real-world functioning. Neuropsychological performance predicted functional capacity, which predicted all three domains of real-world functioning. Depression predicted interpersonal and work skills, while negative symptoms affected interpersonal skills independently of other predictors. CONCLUSIONS: Real-world adaptive life skills are predicted by neuropsychological performance, symptoms, and functional capacity. Neuropsychological performance contributes little to the prediction of real-world performance after accounting for functional capacity. In some domains, negative and depressive symptoms influenced real-world performance while not relating to functional capacity or neuropsychological performance.

Activities of Daily Living↗

PubMed2006

Association between dyads and correct responses on the Paced Auditory Serial Addition Task (PASAT).

The sensitivity of the Paced Auditory Serial Addition Task (PASAT) to working memory deficits may be enhanced by examining "dyads" (i.e., correct responses immediately preceded by a correct response) as a complement to the traditional total correct summary score. In a sample of 397 mostly African American (79%) healthy adults, total dyad and total correct scores were highly correlated (r = .96, p < .001); however, the magnitude of this association diminished in faster stimulus presentation trials, particularly among participants with impaired working memory abilities.

Adult↗

PubMed2005

Construct validity of Hopkins Verbal Learning Test-Revised component process measures in an HIV-1 sample.

Executive dyscontrol of episodic verbal learning and memory secondary to prefrontostriatal circuit neuropathophysiology is a common feature of HIV-1 infection. Prior research indicates that standard clinical learning and recall indexes from Hopkins Verbal Learning Test-Revised (HVLT-R) are among the most sensitive indicators of HIV-associated neurocognitive disorders. Emerging data support the validity of qualitative component process measures derived from the HVLT-R (e.g., Semantic Clustering); however, no prior studies have examined these particular indices of performance in an HIV-1-infected population. In the present study, we examined the construct validity of HVLT-R component process indices in a sample of 42 persons with HIV-1 infection and 29 demographically similar seronegative comparison participants. The HIV-1 sample performed significantly below the seronegative group on Total and Delayed Recall, Semantic Clustering, and the Retrieval Index. No between-group differences were observed on Serial Clustering, Pair Frequency, Learning, Repetitions, Semantic False Positive Recognition Errors, or the Recognition Discrimination Index. In addition, the HVLT-R component process measures demonstrated evidence of convergent and divergent validity with standard clinical tests in the HIV-1 sample. Findings support the construct validity of HVLT-R component process measures and are commensurate with prior literature indicating that HIV-1 disease is associated with deficient executive control of encoding and retrieval within verbal episodic memory.

Adult↗

PubMed2005

A battery approach for measuring neuropsychological change.

The accurate interpretation of serial neuropsychological testing is a fundamental activity of neuropsychologists in clinical and research settings. Although prior research supports the construct validity of several individual tests for the reliable measurement of cognitive change, neuropsychologists are often interested in detecting changes in cognitive functioning across a battery of tests. In the present study, we examined the specificity of a modified Reliable Change Index (RCI) methodology applied across a focused battery of commonly used neuropsychological tests. Fifty-seven healthy controls underwent neuropsychological assessment at two time points separated by approximately 1 year. Test-retest reliability coefficients and standard RCI confidence intervals for the individual tests were broadly comparable with prior research in healthy populations. Battery change scores were generated by calculating z-scores of change for each individual test, which were summed across the entire test battery. The RCI methodology was applied to the summed z-score to provide a 90% confidence interval as an indicator of overall cognitive stability. These battery RCI normative standards demonstrated adequate specificity when applied to 29 persons with HIV-1 infection who were classified as medically and neurologically stable. Findings from this study may be useful for both clinicians and researchers seeking normative standards for determining reliable changes in performance across a commonly used battery of neuropsychological tests.

Adult↗