Differential effects of mental stress on plasma homovanillic acid in schizophrenia and normal controls.
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We previously reported that mental stress by Kraepelin's arithmetic test decreases plasma homovanillic acid (pHVA) levels in psychiatrically normal healthy human subjects. The present study was undertaken to determine whether this pattern of changes in pHVA concentrations resulting from mental stress is altered in patients with schizophrenia. Fourteen male patients with schizophrenia including those under ongoing neuroleptic treatment and 14 normal male volunteers participated in the study. Following overnight fast and restricted physical activity, the subjects performed Kraepelin's arithmetic test for 30 minutes. Plasma samples were collected immediately before and after the test for measurement of pHVA levels. A significant diagnosis by Kraepelin's test effect was observed due to a decrease in pHVA levels by the Kraepelin test in control subjects but not in patients with schizophrenia. Changes in pHVA levels during the Kraepelin test positively correlated with pre-test pHVA levels in control subjects, while this correlation was not observed in patients with schizophrenia. These results may be further support for the presence of a dopamine-dependent restitutive system in the brain. The absence of response of pHVA levels to mental stress in patients with schizophrenia may indicate that the dopamine restitutive system in these patients is disrupted or already down-regulated, as previously predicted. (+info)
Neurocognitive and social functioning in schizophrenia.
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This cross-sectional study examined the relationships between neurocognitive and social functioning in a sample of 80 outpatients with DSM-III-R schizophrenia. The neurocognitive battery included measures of verbal ability, verbal memory, visual memory, executive functioning, visual-spatial organization, vigilance, and early information processing. Positive and negative symptoms were assessed with the Positive and Negative Syndrome Scale. A range of social behaviors were assessed using the Social Functioning Scale (SFS), the Quality of Life Scale (QLS), and a video-based test, the Assessment of Interpersonal Problem-Solving Skills (AIPSS). Social functioning as assessed by the SFS was unrelated to neurocognitive functioning. Poor cognitive flexibility was associated with low scores on the QLS and the AIPSS. Verbal ability and verbal memory were also significantly associated with the AIPSS. Visual-spatial ability and vigilance were associated with the sending skills subscale of the AIPSS. In this study, which used a wide range of neurocognitive tests and measures of community functioning and social problem solving, results support earlier research that suggests an association between certain aspects of neurocognitive functioning and social functioning. (+info)
Ziprasidone 80 mg/day and 160 mg/day in the acute exacerbation of schizophrenia and schizoaffective disorder: a 6-week placebo-controlled trial. Ziprasidone Study Group.
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In this double-blind study, patients with an acute exacerbation of schizophrenia or schizoaffective disorder were randomized to receive either ziprasidone 80 mg/day (n = 106) or 160 mg/day (n = 104) or placebo (n = 92), for 6 weeks. Both doses of ziprasidone were statistically significantly more effective than placebo in improving the PANSS total, BPRS total, BPRS core items, CGI-S, and PANSS negative subscale scores (p < .05). Ziprasidone 160 mg/day significantly improved depressive symptoms in patients with clinically significant depression at baseline (MADRS > or = 14, over-all mean 23.5) (p < .05) as compared with placebo. The percentage of patients experiencing adverse events was similar in each treatment group, and resultant discontinuation was rare. The most frequent adverse events associated with ziprasidone were generally mild dyspepsia, nausea, dizziness, and transient somnolence. Ziprasidone was shown to have a very low liability for inducing movement disorders and weight gain. The results indicate that ziprasidone is effective and well tolerated in the treatment of the positive, negative, and depressive symptoms of an acute exacerbation of schizophrenia or schizoaffective disorder. (+info)
Activation of Heschl's gyrus during auditory hallucinations.
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Apart from being a common feature of mental illness, auditory hallucinations provide an intriguing model for the study of internally generated sensory perceptions that are attributed to external sources. Until now, the knowledge about the cortical network that supports such hallucinations has been restricted by methodological limitations. Here, we describe an experiment with paranoid schizophrenic patients whose on- and offset of auditory hallucinations could be monitored within one functional magnetic resonance imaging (fMRI) session. We demonstrate an increase of the blood oxygen level-dependent (BOLD) signal in Heschl's gyrus during the patients' hallucinations. Our results provide direct evidence of the involvement of primary auditory areas in auditory verbal hallucinations and establish novel constraints for psychopathological models. (+info)
Psychophysical isolation of a motion-processing deficit in schizophrenics and their relatives and its association with impaired smooth pursuit.
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Schizophrenia patients and many of their relatives show impaired smooth pursuit eye tracking. The brain mechanisms underlying this impairment are not yet known, but because reduced open-loop acceleration and closed-loop gain accompany it, compromised perceptual processing of motion signals is implicated. A previous study showed that motion discrimination is impaired in schizophrenia patients. Motion discrimination can make use of position and contrast as well as velocity cues. Here, we report that the motion discrimination deficit, which occurs in both schizophrenic patients and in their first-degree relatives, involves a failure of velocity detection, which appears when judging intermediate target velocities. At slower and faster velocities, judgments of velocity discrimination seemed normal until we experimentally disentangled velocity cues from nonmotion cues. We further report that compromised velocity discrimination is associated with sluggish initiation of smooth pursuit. These findings point to specific central nervous system correlates of schizophrenic pathophysiology. (+info)
Concurrent performance of motor tasks and processing capacity in patients with schizophrenia.
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Any task is carried out more successfully if we allocate undivided attention to it, but as demands on attentional capacity increase-for example, in concurrent or dual task conditions-performance on attended tasks becomes more impaired. Patients with schizophrenia show impaired performance on tasks requiring high levels of attentional capacity. This study examines performance of 11 patients with schizophrenia and 13 normal controls on two motor tasks (placing pegs in a pegboard and repetitive index finger tapping) under unimanual, bimanual, and dual task conditions. The patients with schizophrenia placed fewer pegs and had reduced tapping speed in unimanual and bimanual conditions. However, the decrement in bimanual performance as a percentage of unimanual performance was not significantly different for the patients and controls on either the pegboard or tapping tasks. By contrast, under dual task conditions, the performance of the patients with schizophrenia in peg placement actually improved relative to the unimanual pegboard task, whereas tapping performance deteriorated compared with the unimanual tapping, a decrement that was significantly greater for the patients. Thus the improvement in the visually guided pegboard task was at the expense of the repetitive tapping task. These results are discussed in terms of an impairment of self initiated movement with general sparing of externally triggered movements in schizophrenia and the role of frontostriatal loops in this process. (+info)
Computed tomographic findings in schizophrenia: relation with symptom dimensions and sex differences.
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OBJECTIVE: Loss of grey matter, a consistent finding in schizophrenia, is likely to be influenced by symptom heterogeneity and sex. This study was conducted to determine the extent and region of brain atrophy in schizophrenia and its relation to symptom syndromes and to patient sex. DESIGN: Prospective study of consecutive patients. SETTING: Psychiatric department of a general teaching hospital. PATIENTS: Sixty-one consecutive patients (37 men and 24 women) admitted to hospital for acute exacerbation of schizophrenia, as diagnosed according to the DSM third edition, revised. INTERVENTIONS: Computed tomographic examination of the head. OUTCOME MEASURES: Diffuse atrophy and atrophy in the frontal and temporal regions and the sylvian fissure were rated using the CT Rating Scale for Schizophrenia. Ratings were contrasted between male and female subjects; relations between atrophy ratings and 3 symptom dimensions of schizophrenia were examined for male and female subjects separately. RESULTS: Widening of the sylvian fissure was positively related to psychomotor poverty (r = 0.32, p < 0.01). There was a significantly stronger relation between diffuse atrophy and reality distortion in female than in male subjects. There was no sex difference in the atrophy rating in all regions of the brain, and this lack of sex difference was not related to age of onset, length of illness or age at the time of the CT scan. CONCLUSION: The morphological changes in the brain on CT are no greater in men than in women with schizophrenia. Different mechanisms may be involved in producing reality distortion symptoms in men and women. (+info)
Disruption of latent inhibition in rats with postnatal hippocampal lesions.
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Disruption of latent inhibition has been proposed as a possible model of cognitive abnormalities that underlie positive symptoms of a schizophrenia. We tested neonatal hippocampal lesioned rats in a latent inhibition paradigm. Lesions of the ventral hippocampus were induced by bilateral injections of ibotenic acid in 7 days old rats. The behavior of lesioned rats was tested postpubertally. We found a hyperresponsiveness to dopaminergic stimulation by apomorphine in locomotion tests. Latent inhibition was tested using the acquisition of a conditioned reaction in a two-way shuttle box. Sham operated control animals showed after preexposure of the to-be-conditioned stimulus (combined tone and light stimulus) a low acquisition. Ibotenic acid lesioned animals learned the conditioned reaction with and without preexposure in the same way, indicating disturbed latent inhibition. These results demonstrate disturbances in early postnatal hippocampal lesioned rats comparable with those seen in schizophrenic patients, thus further validating this procedure as a useful animal model of some aspects of schizophrenia. (+info)