Schizophrenia is a major psychiatric disease, which affects the centre of the personality, with severe problems of perception, cognition as well as affective and social behaviour. In cerebrospinal fluid of drug-free schizophrenic patients, a significant decrease in the level of total glutathione (GSH) by 27% (P<0.05) was observed as compared to controls, in keeping with the reported reduced level of its metabolite gamma-glutamylglutamine. With a new non-invasive proton magnetic resonance spectroscopy methodology, GSH level in medial prefrontal cortex of schizophrenic patients was found to be 52% (P = 0.0012) lower than in controls. GSH plays a fundamental role in protecting cells from damage by reactive oxygen species generated among others by the metabolism of dopamine. A deficit in GSH would lead to degenerative processes in the surrounding of dopaminergic terminals resulting in loss of connectivity. GSH also potentiates the N-methyl-D-aspartate (NMDA) receptor response to glutamate, an effect presumably reduced by a GSH deficit, leading to a situation similar to the application of phencyclidine (PCP). Thus, a GSH hypothesis might integrate many established biological aspects of schizophrenia.

Altered negative feedback control of the hypothalamic-pituitary-adrenocortical (HPA) system is a frequent laboratory sign of major depression. It coincides with depressive episodes and partially reverses after recovery from psychopathology. Such an HPA disturbance in feedback control can be acquired as a result of stressful life experiences and be compounded by age or it can be genetically predetermined at all levels involved in fine-tuned neuroendo-crine regulation. Major psychiatric disorders run in families and a high familial load for an affective illness therefore increases an individual’s risk of becoming affected. We investigated whether the HPA feedback disturbance observed among patients with depression is present in otherwise healthy individuals who are at high risk for psychiatric disorders because they have a first-degree relative with an affective illness. Using rigid psychodiagnostic techniques, we screened 431 consecutively admitted patients with depression and identified 35 families with one or more high-risk probands (HRPs). The results of a combined dexamethasone/human corticotropin-releasing hormone (DEX-CRH) test showed that the group of dexamethasone-pretreated (1.5 mg; 23.00 h) HRPs released more cortisol after stimulation with human CRH (100 µg; 15.00 h the next day) than a control group (CPs), but less than a group of patients with an acute major depressive episode (DPs). The peak cortisol values were 146.1 ± 147.7 nmol/l (mean ± SD) (HRPs), 75.3 ± 47.9 nmol/l (CPs) and 278.2 ± 199.2 nmol/l (DPs), yielding significant (F = 9.66, p < 0.001) group differences, with values for HRPs vs. CPs and HRPs vs. DPs being significant at the 1 % level (t test). The adrenocorticotropin (ACTH) responses of the HRPs did not exceed control levels, suggesting that over time the adrenocortical gland had developed a hypersensitivity, possibly secondary to long-term overexposure to ACTH. A linear discriminant analysis identified 32% of the HRPs as showing cortisol response patterns indistinguishable from those of DPs. These and other data analyses revealed the presence of an HPA feedback disturbance in a substantial number of subjects at risk for affective illness. Our findings suggest that the negative feedback defect in a number of healthy probands at risk for affective disorder is caused by a disturbed corticosteroid receptor function. In the absence of current or previous psychiatric disorder or environmental factors such as specific lifestyles that could have led to adaptive changes in corticosteroid receptor function in our subjects, we conclude that our findings are best understood as indicating a genetically transmitted risk factor, possibly rendering these individuals susceptible to affective disorders.

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