Functional anatomy of verbal fluency in people with schizophrenia and those at genetic risk. Focal dysfunction and distributed disconnectivity reappraised.

BACKGROUND: PET studies of verbal fluency in schizophrenia report a failure of 'deactivation' of left superior temporal gyrus (STG) in the presence of activation of left dorsolateral prefrontal cortex (DLPFC), which deficit has been attributed to underlying 'functional disconnectivity'. AIM: To test whether these findings provide trait-markers for schizophrenia. METHOD: We used H2(15)O PET to examine verbal fluency in 10 obligate carriers of the predisposition to schizophrenia, 10 stable patients and 10 normal controls. RESULTS: We found no evidence of a failure of left STG deactivation in carriers or patients. Instead, patients failed to deactivate the precuneus relative to other groups. We found no differences in functional connectivity between left DLPFC and left STG but patients exhibited significant disconnectivity between left DLPFC and anterior cingulate cortex. CONCLUSIONS: Failure of left STG 'deactivation' and left fronto-temporal disconnectivity are not consistent findings in schizophrenia; neither are they trait-markers for genetic risk. Prefrontal functional disconnectivity here may characterise the schizophrenic phenotype.

No evidence for left superior temporal dysfunction in asymptomatic schizophrenia and bipolar disorder. PET study of verbal fluency.

BACKGROUND: Positron emission tomography (PET) studies have revealed functional left superior temporal gyrus (STG) abnormalities in symptomatic schizophrenia during word generation. AIMS: To discover if this dysfunction is present in asymptomatic schizophrenia. To determine whether, without concurrent symptomatology, schizophrenia and bipolar affective disorder (BPD) are distinguishable by differing regional cerebral blood flow (rCBF) patterns during word generation. METHOD: A PET verbal fluency protocol was applied to six patients with BPD in remission and six patients with asymptomatic schizophrenia. Analysis included 10 control subjects from a contemporaneous study. RESULTS: All groups showed relative reduction of rCBF in both superior temporal cortices. There were no quantitative differences in any group comparison. All groups exhibited negative covariation between rCBF in left prefrontal and right (but not left) temporal regions. CONCLUSIONS: Abnormal patterns of left STG function cannot be regarded as a trait marker for schizophrenia. Functional abnormalities may reflect aspects of mental state.

Schizophrenia: developmental disturbance of brain and mind?

Schizophrenia is the most severe of the mental illnesses and affects approximately 0.8% of the population in Western societies. Postmortem and neuroimaging studies show that patients with schizophrenia have slightly larger cerebral ventricles than normal and a decrease in cortical volume, most markedly in the left temporal lobe. These changes are present at diagnosis and appear to show little change over extended periods of follow-up. Associated findings such as lack of normal cerebral asymmetry and cytoarchitectonic changes suggestive of impaired migration of cortical neurons implicate aberrant neurodevelopment. Schizophrenics also show an excess of pregnancy and birth complications, and an association with prenatal exposure to maternal influenza. These and reports of abnormal psychological development in pre-schizophrenic children add further support to the theory that the disorder has neurodevelopmental origins.

Psychiatric patients and HIV infection: a new population at risk?

BACKGROUND: We assess the evidence that psychiatric patients are at increased risk of infection with HIV and discuss some of the clinical implications. METHOD: Surveys of HIV seroprevalence and risk behaviours among psychiatric patients were obtained from a manual and computer search (Medline and AIDSline). RESULTS: Most studies report an increased prevalence of HIV infection among psychiatric patients compared to the general population. Risk behaviours, and obstacles to risk reduction, are identified. CONCLUSIONS: There is a strong case for investigating the seroprevalence of HIV in psychiatric settings in the UK. Issues relating to HIV and AIDS are likely to assume increasing importance in general psychiatric practice.

The concept of disease: its evolution in medical students.

First, third and fifth year medical students were asked to say to what extent they considered each of 38 conditions to be a disease, to be treatable, to be serious, to be the fault of the patient and to be external in cause. Fifth year students were significantly more inclusive in their use of the term disease, applying it to far more conditions, with third year students midway between the first and fifth year students. The use of the term disease did not relate to any great extent with its treatability, seriousness, blame or externality. The concept of disease, despite the difficulty of a consistent, formal philosophical definition, is heuristically useful, and is applied readily by medical students, evolving as students progress through medical school, in a way that cannot be explained in relation to other perceptions of the conditions.