In this article an overview is given of the differential diagnosis of autism and autistic-like disorders. The diagnosis of the so-called ‘Multiple Complex Developmental Disorders’ (MCDD) as a distinct entity is discussed in relation to autism and schizophrenia.

Biological research and the relevance of results until recently are discussed. Finally, the importance of the hypothalamic-pituitary-adrenal system (HPA system) as a model for research is proposed. Research on the flexibility of this system may contribute in understanding the ways of stress processing in disorders like autism, MCDD and schizophrenia.

In this investigation the effects of immune activation on the brain are characterized. In order to study this, we used a model for chronic immune activation, the myocardial infarction, and intravenous injections with the pro-inflammatory cytokine Tumour Necrosis Factor alpha (TNF-α). The incentive for this study is the observation that myocardial infarction is accompanied by behavioural and neuronal abnormalities. The effects of myocardial infarction on the brain and its functioning are widespread. In order to examine the mechanism through which this interaction occurs, a group of rats underwent an experimentally induced myocardial infarction whereafter immunohistochemistry was performed on slices of the brain. This experiment revealed regional serum protein extravasation, pointing to leakage of the blood-brain barrier. This process occurred in certain cortical, subcortical and hindbrain areas in discrete patches. The leakage was co-localized with the expression of the immune activation marker ICAM-1. A second group of rats was therefore injected with TNF-α, a major pro-inflammatory cytokine, to assess the involvement of the immune system in the effects shown. This procedure rendered the same results. It is concluded that myocardial infarction may interfere with the integrity of the blood-brain barrier and possibly with brain functioning through activation of the immune system. The relevance for pathophysiological processes is discussed.

This paper reviews the relationship between cholesterol and psychological functioning. Possibly a relationship exists between the lowering of cholesterol, low serum cholesterol concentration and mood and/or impulse control disorders. This might be associated with a disregulated cerebral serotonin metabolism. These hypotheses are based on (meta-analyses of) epidemiologic research investigating the lowering of cholesterol. One of the findings was an increased mortality due to suicide, homicide and accidents. Much is still unknown about the matters mentioned above. However, recommendations for research and clinical psychiatric practice are formulated.

Since the introduction of international psychiatric classification systems, systematic diagnostic methods have become available for personality disorders. Recent developments in the dimensional diagnostic approach of personality disorders have yielded relationships between this type of disorders and neurobiological processes including both monoaminergic and stress-hormonal systems. It is hypothesized that the pathogenesis of borderline personality disorders is related to an enhanced serotonergic tone in septo-hippocampal structures. Preliminary clinical data are suggestive for potential therapeutic effects of serotonin-modulating compounds in borderline personality disorders