Factor versus cluster models of schizotypal traits. I: a comparison of unselected and highly schizotypal samples.

Factor analytic studies have long supported the division of schizophrenic symptoms into three relatively orthogonal factors: positive symptoms, negative symptoms, and disorders of relatedness/disorganization. Similarly, factor analyses of schizotypy often yield three factors: positive symptoms, negative symptoms, and social anxiety or disorganization. Recent cluster analyses, however, suggest that not all patients can be simply categorized according to these factors. Cluster analyses of schizotypal symptoms tend to result in clusters of individuals who are low in all factors, high in more than one factor, or high predominantly in one factor. The present study sought to compare factor and cluster models of schizotypal symptoms, as measured by the SPQ, PAS, and MIS, in unselected individuals and highly schizotypal individuals. Consistent with prior research, factor analysis of a large unselected undergraduate sample yielded three factors: "positive", "negative", and "disorganized." Factor analysis of schizotypal undergraduates produced the same three factors, plus a fourth designated "paranoid thinking." In contrast, cluster analysis of the unselected sample yielded four clusters ("low schizotypy", "average schizotypy", and "high schizotypy", plus "positive/disorganized"). Cluster analysis of the schizotypal subsample produced four clusters: "low schizotypy", "positive", "negative" and "high schizotypy."     

Vulnerability to schizophrenia: neuropsychological performance and schizotypal personality traits]

Although some neuropsychological deficits and a high rate of schizotypal personality disorders have been found in the first-degree relatives of patients with schizophrenia, few studies have looked for a link between those two types of potential marker of vulnerability to this disease. The aims of this study were: 1) to confirm some executive/attentional deficits in a group of first-degree relatives including not only siblings but also parents; 2) to evaluate the schizotypal traits using the French version of 4 self-reporting scales proposed by Chapman and his colleagues; 3) to look for a dependence or independence between the neuropsychological performance and the scores on the scales of schizotypy. Twenty four patients with schizophrenia, 48 of their first-degree relatives and 31 controls were included in the study. Both attentional tests (a Digit Symbol Substitution Test and a Degraded Stimulus-Continuous Performance Test) confirmed a worse performance in the patient and in the first-degree relative groups than in the control group. On the opposite side, the executive performance assessed by the Wisconsin Sorting Card Test, was poorer in the patient group only. Scores of the first-degree relative group on the social anhedonia, physical anhedonia and perceptual aberrations scales were at an intermediate level between those of the patient and control groups; moreover, only scores on the social anhedonia scale tended to be significantly higher in the first-degree relative group than in the control group. Among the first-degree relative group, the only significant correlation found was between the number of perseverative errors on the WCST and the scores on the physical anhedonia scale.     

Differential association of HIV-related neuropsychological impairment with semantic versus repetition priming.

There is evidence that the facilitating effects of stimulus repetition (repetition or identity priming) are mediated by visuoperceptual functions local to extrastriate cortex. Semantic or verbal-associative priming, on the other hand, is believed to be a function of more anterior brain systems. The present study finds evidence for disrupted semantic priming with intact repetition priming in a cognitively impaired HIV+ sample. These results are consistent with recent brain-imaging evidence for a subcortical and white-matter locus for HIV associated neuropathology resulting in effects on subcortical-frontal systems.     

Early HIV-related neuropsychological impairment: Relationship to stage of viral infection

Abstract

Sixty male outpatients with no past neuropsychiatric history were examined for evidence of early HIV-related neuropsychological impairment. Significant cognitive deficit, as measured by the RAVLT and WAIS-R Digit Symbol Substitution tests, and moderate correlation with indices of immune function, were observed in a group of patients with AIDS-Related Complex [ARC]. Patients with asymptomatic HIV-infection demonstrated no significant differences in performance compared to a group of HIV-seronegative controls. No significant group differences in age, education, predicted-IQ or self-rated depression and anxiety were observed. These results support the hypothesis that HIV-related cognitive disturbance occurs within the context of immunosuppression.     

Early HIV-related neuropsychological impairment: relationship to stage of viral infection

Sixty male outpatients with no past neuropsychiatric history were examined for evidence of early HIV-related neuropsychological impairment. Significant cognitive deficit, as measured by the RAVLT and WAIS-R Digit Symbol Substitution tests, and moderate correlation with indices of immune function, were observed in a group of patients with AIDS-Related Complex [ARC]. Patients with asymptomatic HIV-infection demonstrated no significant differences in performance compared to a group of HIV-seronegative controls. No significant group differences in age, education, predicted-IQ or self-rated depression and anxiety were observed. These results support the hypothesis that HIV-related cognitive disturbance occurs within the context of immunosuppression.     

Longitudinal change in neuropsychological performance using latent growth models: a study of mild cognitive impairment

The goal of the current study was to examine cognitive change in both healthy controls (n?=?229) and individuals with mild cognitive impairment (MCI) (n?=?397) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). We applied latent growth modeling to examine baseline and longitudinal change over 36 months in five cognitive factors derived from the ADNI neuropsychological test battery (memory, executive function/processing speed, language, attention and visuospatial). At baseline, MCI patients demonstrated lower performance on all of the five cognitive factors when compared to controls. Both controls and MCI patients declined on memory over 36 months; however, the MCI patients declined at a significantly faster rate than controls. The MCI patients also declined over 36 months on the remaining four cognitive factors. In contrast, the controls did not exhibit significant change over 36 months on the non-memory cognitive factors. Within the MCI group, executive function declined faster than memory, while the other factor scores changed slower than memory over time. These findings suggest different patterns of cognitive change in healthy older adults and MCI patients. The findings also suggest that, when compared with memory, executive function declines faster than other cognitive factors in patients with MCI. Thus, decline in non-memory domains may be an important feature for distinguishing healthy older adults and persons with MCI.     

Season of birth and neuropsychological impairment in schizophrenia.

Repeated studies suggest a relationship between winter birth and increased incidence of schizophrenia. Furthermore, there may be seasonal fluctuations in schizophrenia risk factors (e.g., influenza epidemics) and the severity of biological anomalies (e.g., enlarged cerebral ventricles in neuroimaging studies). In order to assess whether winter-born schizophrenics show greater neuropsychological impairment, 112 males meeting Research Diagnostic criteria for schizophrenia were administered the Luria-Nebraska Neuropsychological Battery, a thorough measure of higher cortical functioning deficit. Sixty-four of these 112 patients were also administered the Wechsler Adult Intelligence Scale-Revised, the Benton Visual Retention Test, and the Rey Auditory Verbal Learning Test. Despite the use of several definitions of winter and nonwinter birth, there was no evidence of elevated rates of neuropsychological dysfunction among winter-born patients on any measure. The current study contains certain limitations (e.g., variable medication status at testing), but the results suggest no strong season of birth relationship with neuropsychological impairment in a reasonably large, research-diagnosed sample of schizophrenic patients.     

Factor structure of the CERAD neuropsychological battery.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery was developed to evaluate cognitive impairments associated with Alzheimer's disease (AD). Previous studies have suggested that the battery is multi-dimensional, represented by either 3 or 5 dimensions. In this study a principal factor analysis was conducted using contemporary quantitative methods for determining the number of factors. Exploratory factor analysis of the CERAD battery and MMSE was conducted using one-half of the CERAD database (total N = 969). Glorfeld's modification of Horn's parallel analysis method suggested that there was 1 common factor in the variable matrix. Characterization of patterns of deficits in AD requires supplementation of measures derived from the CERAD and MMSE with other tests.     

Neural processing of social rejection: the role of schizotypal personality traits

A fear of being rejected can cause perceptions of more insecurity and stress in close relationships. Healthy individuals activate the dorsal anterior cingulate cortex (dACC) when experiencing social rejection, while those who are vulnerable to depression deactivate the dACC presumably to downregulate salience of rejection cues and minimize distress. Schizotypal individuals, characterized by unusual perceptual experiences and/or odd beliefs, are more rejection sensitive than normal. We tested the hypothesis, for the first time, that individuals with high schizotypy also have an altered dACC response to rejection stimuli. Twenty-six healthy individuals, 14 with low schizotypy (LS) and 12 with high schizotypy (HS), viewed depictions of rejection and acceptance and neutral scenes while undergoing functional MRI. Activation maps in LS and HS groups during each image type were compared using SPM5, and their relation to participant mood and subjective ratings of the images was examined. During rejection relative to neutral scenes, LS activated and HS deactivated the bilateral dACC, right superior frontal gyrus, and left ventral prefrontal cortex. Across both groups, a temporo-occipito-parieto-cerebellar network was active during rejection, and a left fronto-parietal network during acceptance, relative to neutral scenes, and the bilateral lingual gyrus during rejection relative to acceptance scenes. Our finding of dACC-dorso-ventral PFC activation in LS, but deactivation in HS individuals when perceiving social rejection scenes suggests that HS individuals attach less salience to and distance themselves from such stimuli. This may enable them to cope with their higher-than-normal sensitivity to rejection.     

Two models of impulsivity: relationship to personality traits and psychopathology.

BACKGROUND: Impulsivity is prominent in psychiatric disorders. Two dominant models of impulsivity are the reward-discounting model, where impulsivity is defined as inability to wait for a larger reward, and the rapid-response model, where impulsivity is defined as responding without adequate assessment of context. We have compared the role of these models of impulsivity in human psychopathology, based on the hypothesis that rapid-response impulsivity would be more strongly related to other aspects of psychopathology and to impulsivity as described by questionnaires.METHODS: We investigated relationships between personality and laboratory measures of impulsivity, and between these measures and clinical characteristics, in parents of adolescent subjects with disruptive behavioral disorders (DBDs) and matched control subjects. Diagnoses were rendered using the Structured Interview for DSM-IV. The Barratt Impulsiveness Scale (BIS) was used as a trait measure of impulsivity. Rapid-response impulsivity was assessed using a form of the Continuous Performance Test, the Immediate Memory-Delayed Memory Task (IMT/DMT). Reward-delay impulsivity was measured using two tasks where subjects could choose between smaller immediate or larger delayed rewards.RESULTS: Rapid-response, but not reward-delay impulsivity, was significantly higher in subjects with lifetime Axis I or Axis II diagnoses. Scores on the BIS were elevated in subjects with Axis I diagnoses and correlated significantly with both rapid-response and reward-delay tests, but more strongly with the former. Multiple regression showed that rapid-response, but not reward-delay performance or intelligence quotient, contributed significantly to BIS scores. Correlations were similar in parents of control subjects and of DBD subjects.CONCLUSIONS: These data suggest that measures of rapid-response impulsivity and of reward-delay impulsivity are both related to impulsivity as a personality characteristic. The relationship appears stronger, however, for rapid-response impulsivity, as measured by the IMT/DMT. Laboratory and personality measures of impulsivity appear to be related to risk of psychopathology.     

The impact of HIV-associated neuropsychological impairment on everyday functioning.

HIV-1 infection can be associated with neuropsychological (NP) deficits ranging from subtle to severe. The purpose of this study was to evaluate the functional, or "real-world" impact of HIV-associated NP impairment in a group of 267 HIV-infected participants. All participants received comprehensive NP, neuromedical, and standardized functional evaluations that included laboratory measures of shopping, cooking, financial management, medication management and vocational abilities. Compared to NP-normal participants, those with NP impairment performed significantly worse on all laboratory measures of everyday functioning. Multivariate analyses revealed that the NP ability domains of Abstraction/Executive Function, Learning, Attention/Working Memory and Verbal abilities most strongly and consistently predicted failures on the functional battery. Both NP impairment and impairment on the functional battery were significantly associated with subjective experiences of cognitive difficulties, as well as unemployment and increased dependence in activities of daily living; multivariate prediction models that also considered depressed mood and biological measures of disease progression revealed that impairment on the functional battery and depression were the only unique predictors of all three indicators of "real-world" functioning. The current results add to growing evidence concerning the clinical significance of HIV-associated NP impairment. Objective, laboratory based functional measures, such as those used here, may compliment NP testing in future studies directed at understanding the impact on life quality of central nervous system disorders and their treatments. Finally, there is a need for additional research investigating the apparently independent effect of depression on level of everyday functioning in HIV infected persons.     

Solvent-induced toxic encephalopathy: Electrophysiological data in relation to neuropsychological findings

Abstract

Male subjects with type 2A (n = 12) and 2B (n = 12) solvent-induced toxic encephalopathy and a reference group of healthy men (n = 12) without previous solvent exposure were studied using quantitative EEG and event-related potentials from an odd-ball and a dual-task paradigm. Subjects with toxic encephalopathy of types 2A and 2B showed markedly lower P300 amplitudes than did controls in both paradigms. In the relatively complex dual-task setting, subjects with 2A and 2B showed lower signal detection than did controls.     

Focal cognitive impairment in mitochondrial encephalomyopathies: a neuropsychological and neuroimaging study.

Mitochondrial encephalomyopathies (ME) are a multisystemic group of diseases characterized by a wide range of biochemical and genetic mitochondrial defects with a variable mode of inheritance. We studied the neuropsychological profile, magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) data in a group of ME patients in order to look for common or specific cognitive defects and a possible correlation with related brain areas. Three main cognitive areas were assessed: general intelligence, memory functions and visuo-perceptual skills. Our sample included 16 ME patients (nine males, seven females) aged 25-68 years (mean age 45.2, SD 13.0). No sign of mental deterioration was found in the group of elderly subjects. Despite subjects showing no global cognitive impairment they scored lower in nonverbal versus verbal tasks. Visuo-spatial skills and short-term memory were selectively impaired. There was no correlation between neuropsychological results and age, illness duration, age of onset, clinical phenotypes, genetic mitochondrial alterations and pharmacological therapy. The most frequent SPECT pattern observed was the hypoperfusion of temporal lobes, with a direct localization in the temporal cortex and with prevalent mesial involvement. The neuropsychological profile and SPECT imaging revealed similarities with focal defects.     

The neuropsychological profile of psychotic major depression and its relation to cortisol.

BACKGROUND: Our study described the neuropsychological profile of psychotic major depression (PMD) compared to nonpsychotic major depression (NPMD) patients and psychiatrically healthy controls (HC). We predicted that higher cortisol levels would be associated with greater cognitive deficits. METHODS: Twenty-nine PMDs, 24 NPMDs, and 26 HCs were recruited at Stanford University Medical Center. Psychiatric ratings, cortisol levels from 1800-0900 hours, and neuropsychological test data were obtained. RESULTS: PMDs had more severe cognitive impairments compared with NPMDs and HCs with the exception of simple verbal attention. PMDs had elevated mean cortisol levels from 1800 to 0100 hours which were significantly correlated with poorer verbal memory and psychomotor speed performance. Cortisol slopes from 1800 to 0100 hours were also significantly correlated with verbal memory and working memory. CONCLUSIONS: While PMDs' ability to attend passively to information appears intact, they have more difficulty processing, manipulating, and encoding new information. Elevated cortisol levels, as seen in PMD patients, are associated with poorer cognitive performance especially related to verbal memory for lists of words and working memory.     

Magnetic resonance imaging correlates of neuropsychological impairment in multiple sclerosis.

The authors examined whether specific neuropsychological abnormalities in multiple sclerosis (MS) are associated with focal lesion areas detected by MRI. Lesion area, regardless of distribution, correlated with performance on the vast majority of neuropsychological procedures. No significant difference appeared between groups with normal/mild and moderate overall cognitive impairment on any of the MRI measures. However, patients with severe cognitive impairment had greater lesion area, regardless of location, and had significant atrophy of the corpus callosum compared with the other two groups. These results suggest that severe atrophy of the corpus callosum reflects global disease and provides a relatively focal morphological marker of severe cognitive impairment in MS.