Michael R. Basso

Neuropsychological correlates of negative, disorganized and psychotic symptoms in schizophrenia

Recent studies suggest that three dimensions (negative, disorganized and psychotic) categorize schizophrenic symptoms. A developing literature indicates distinct cerebral correlates of each symptom cluster, but few investigations have determined their neuropsychological correlates. In the present study, the Schedules of Negative and Positive Symptoms measured symptom severity in 62 schizophrenics, and a subsequent principal components analysis revealed three symptom dimensions. Factor scores, age and parental socio-economic status were simultaneously entered into regression equations to explain variance across a broad neuropsychological test battery. Negative symptoms were associated with deficits involving intelligence, executive function, memory, sustained-attention and sensory-motor function, whereas disorganized symptoms correlated with decreased intelligence, attention-span and sensory-motor function. Psychotic symptoms were unrelated to deficits. These data are consistent with hypotheses that these three symptom dimensions have distinct neurobehavioral correlates.

Relative memory deficits in recurrent versus first-episode major depression on a word-list learning task.

Although memory deficits are associated with major depressive disorder, few studies have identified which patient characteristics predict impairment. Because recurrent depression appears related to more severe cerebral dysfunction, the present study tested whether recurrent depressed individuals have worse memory function than first-episode depressed individuals. Two groups of young-adult, nonpsychotic, depressed inpatients (20 single episode [SE] and 46 recurrent episode [RE]) were administered the California Verbal Learning Test within a broader battery of neuropsychological tests. The groups were equivalent in age, education, estimated IQ, severity of depression, and demographic composition. The RE group demonstrated memory deficits relative to both the SE group and published norms, but no other significant difference was found across the battery. Data indicate that abnormal memory performance is associated with recurrent depression, whereas memory deficits are not prominent in first-episode depressed individuals.

Estimated premorbid intelligence mediates neurobehavioral change in individuals infected with HIV across 12 months.

This study tested whether estimated premorbid intelligence moderates worsening neurobehavioral dysfunction in HIV infection. 155 homosexual men (54 controls, 49 HIV+ asymptomatic, 24 HIV+ symptomatic, 28 AIDS) with stable disease status were tested on measures of executive function at baseline and 12-month follow-up. Premorbid intelligence was estimated on the basis of a demographically-based regression equation (Hamsher, 1984), and participants were classified as average or above-average intelligence. Regardless of disease status, participants with above-average IQ showed no declines on measures of executive function across time. In contrast, among those with average IQ, symptomatic groups showed declines, whereas the asymptomatic group did not. The findings support the hypothesis that estimated premorbid intelligence mediates declines in neuropsychological function in patients with stable HIV status. These findings are consistent with theoretical models of cognitive reserve capacity.

Practice Effects on the WAIS-III Across 3- and 6-Month Intervals

Fifty-one participants (age M = 24.6; education M = 14.4 years) were administered the Wechsler Adult Intelligence Scale – Third Edition (WAIS-III) at baseline and at an interval of either 3 or 6 months later. Full Scale IQ (FSIQ), Verbal IQ (VIQ), Performance IQ (PIQ), Verbal Comprehension Index (VCI), Perceptual Organization Index (POI), and Processing Speed Index (PSI) scores improved significantly across time, whereas no significant change occurred on the Working Memory Index. Specifically, test scores increased approximately 3, 11, 6, 4, 8, and 7 points, respectively on the VIQ, PIQ, FSIQ, VCI, POI, and PSI for both groups. Notably, the degree of improvement was similar regardless of whether the inter-test interval was 3 or 6 months. These findings suggest that prior exposure to the WAIS-III yields considerable increases in test scores. Reliable change indices indicated that large confidence intervals might be expected. As such, users of the WAIS-III should interpret reevaluations across these intervals cautiously.

Neuropsychological deficits in psychotic versus nonpsychotic unipolar depression

A broad range of neuropsychological function was compared in samples of young adult unipolar depressed inpatients with and without psychotic features. Consistent with expectations, the psychotic depressive group demonstrated a broad range of deficit and had more impaired performances than the nonpsychotic group. Relevance of these data for hypotheses concerning psychotic depression as a unique diagnostic entity is discussed. In the context of previous research, the current findings suggest that accounting for individual differences in depression may clarify discrepancies between earlier studies of neuropsychological function in depression, and our understanding of the mechanisms by which depression influences cognition may be refined.

Attentional-shaping as a means to improve emotion perception deficits in schizophrenia

Inability to recognize emotional expressions of others (emotion perception) is one of the most common impairments observed among individuals with schizophrenia. Such deficits presumably contribute much to the social dysfunction characteristic of schizophrenia. This study examined the efficacy of a novel attentional-shaping intervention to improve emotion perception abilities. Sixty participants with schizophrenia were randomly assigned to one of three intervention conditions: 1) attentional-shaping, 2) contingent monetary reinforcement, or 3) repeated practice. Participants completed the Face Emotion Identification Test (FEIT) at pre-test, intervention, post-test, and one week follow-up. Participants also completed the Bell-Lysaker Emotion Recognition Test (BLERT) and the Social Behavior Scale at pre-test and follow-up to measure generalization. The results showed that the attentional-shaping condition had significantly higher scores on the FEIT at intervention, post-test, and follow-up compared to monetary reinforcement and repeated practice. Improvement was also found on the BLERT and a trend was found for improved social behaviors at one-week follow-up. Results will be discussed in terms of face scanning and attentional deficits present in schizophrenia and potential uses of this intervention in the remediation of emotion perception deficits.

Perceptions of hostility by persons with and without persecutory delusions

Introduction. Current models of paranoia propose that ambiguous situations, in which cues regarding the intentions of others are lacking, may be perceived as hostile by persons with persecutory delusions (PD). Thus, a social-cognitive bias for the perception of hostility may be present. In this study, the Ambiguous Intentions Hostility Questionnaire (AIHQ) was used to present situations that are ambiguous regarding the intentions of others. It was predicted that on the AIHQ, persons with PD would show greater levels of perceived hostility, blame, and aggression than both psychiatric and nonpsychiatric controls. Methods. The sample comprised 32 persons with PD, 28 persons without PD (psychiatric controls), and 50 healthy participants (nonpsychiatric controls). Participants completed the AIHQ along with measures of paranoia, attributional style, depression, anxiety, self-esteem, and public self-consciousness. Results. As predicted, the group with PD showed greater perceptions of hostility, blame, and aggression scores for ambiguous situations on the AIHQ. Also, the AIHQ Hostility bias score was predictive of paranoid ideation. Conclusions. Persons with PD showed a social-cognitive bias for perceiving hostility in ambiguous situations. The bias appears to be specific as it was not found in the psychiatric or nonpsychiatric control groups. Suggestions for future research are discussed.

Self-generated learning in people with multiple sclerosis

Memory impairment is among the most common cognitive deficits in people with multiple sclerosis (MS). To remediate this problem, recent research has evaluated the benefits of self-generated encoding. These nascent investigations reveal that people with MS who have mild memory impairment demonstrate a significant memory benefit from self-generated encoding compared with didactic learning. To extend prior research, the present experiment included MS patients with moderate-severe, rather than just mild, memory impairment. Additionally, the experiment evaluated whether self-generated encoding improves memory for activities of daily living instead of abstract words. Specifically, the experiment determined whether self-generated encoding enhanced memory for names, appointments, and object locations. In agreement with and extending prior research, MS patients remembered more information if it was self-generated rather than didactically presented, and this finding occurred despite moderate-severe memory impairment. Furthermore, compared with didactic encoding, self-generation enhanced recall of activities of daily living. Implications of these findings for cognitive rehabilitation and the nature of memory impairment in MS are discussed.

Verbal Fluency: Language or Executive Function Measure?

Measures of phonemic and semantic verbal fluency, such as FAS and Animal Fluency (Benton, Hamsher, & Sivan, 1989), are often thought to be measures of executive functioning (EF). However, some studies (Henry & Crawford, 2004a, 2004b, 2004c) have noted there is also a language component to these tasks. The current exploratory factor-analytic study examined the underlying cognitive structure of verbal fluency. Participants were administered language and EF measures, including the Controlled Oral Word Association Test (FAS version), Animal Fluency, Boston Naming Test (BNT), Vocabulary (Wechsler Adult Intelligence Scale-III), Wisconsin Card-Sorting Test (WCST, perseverative responses), and Trail-Making Test-Part B (TMT-B). A 2-factor solution was found with the 1st factor, language, having significant loadings for BNT and Vocabulary, while the second factor was labeled EF because of significant loading from the WCST and TMT-B. Surprisingly, FAS and Animal Fluency loaded exclusively on to the language factor and not EF. The current results do not exclude EF as a determinant of verbal fluency, but they do suggest that language processing is the critical component for this task, even without significant aphasic symptoms. Thus, the results indicated that both letter (phonemic) and category (semantic) fluency are related to language, but the relationship to EF is not supported by the results.

Neurobehavioural consequences of substance abuse and HIV infection

Although our understanding of how human immunodefiency virus (HIV)-related neurobehavioural deficits develop is nascent and preliminary, some clues have emerged which may clarify lingering uncertainties. In particular, HIV seems to yield brain dysfunction by mediating pathological changes upon neuronal function. HIV also compromises immunological integrity, thereby resulting in secondary infections that may further increase brain dysfunction. Notably, many individuals with HIV tend to be current or past abusers of drugs, and, in some cases, their drug use may have actually presented a pathway for initial HIV infection. Similar to HIV, many drugs tend to yield pathological changes upon neuronal function. Further paralleling HIV, some drugs seem to compromise immune function, which in turn may yield secondary detrimental effects upon the brain. Yet, despite the relatively high comorbidity rates of HIV infection and substance abuse, few investigations have addressed the potential interaction between these two factors upon neurobehavioural status. Towards this end, the present paper reviews the existing literature concerning neuropsychological effects of HIV and substance use, and suggests potential mechanisms whereby substance use may potentiate and exacerbate the onset and severity of neurobehavioural abnormalities in HIV infection.