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.

Melatonin is a hormone secreted by the pineal gland mainly during the night. The discovery that this melatonin secretion decreases under the influence of bright light, gave rise to the use of light therapy in some affective disorders. The literature on the relationship between melatonin secretion and mood is reviewed concerning seasonal affective disorder, non-seasonal affective disorder and premenstrual syndrome. Light therapy could reduce an abnormal high melatonin secretion back to normal proportions. None of the affective disorders, however, is accompanied by an unusual high melatonin level. Nevertheless, light therapy as well as other therapies that suppress melatonin have a therapeutic effect. This is not the case with the administration of melatonin. Mood is not affected by extra melatonin in seasonal affective disorder but it is in both other affective disorders. Melatonin plays a part in the pathogenesis of the affective disorders but it is not yet clear which one.

The elucidation of sleep regulation is not an easy task. On one side, there is a multitude of solid yet disparate data, on the other side, the topic is tempting for engaging in wild speculation, particularly with respect to the functions of sleep. Models may exert a moderating influence by mediating between the two extremes. However, also they navigate between the risk of banality in reformulating the obvious, and the peril of fancy in losing touch with empirical reality.

Toxicology is one of the eldest areas of special attention in medicine and pharmacy. In the past, forensic toxicology was the most important part, but nowadays, at least in the Netherlands, the clinical, occupational and environmental toxicology have the centre of attention.

The brain plays its own role in the clinical toxicology. There the intoxication can take place, it can be the basis of the peripheral symptoms of the intoxication or it can be the cause of the intoxication, e.g. at a suicidal attempt or the hospital addiction syndrome.

The somatic treatment of an intoxicated patient includes in the first place the stabilization of the patient (cardio-vascular, ventilation and central effects); then the removal of the poison from the surroundings and out of the patient by different suitable methods and finally the symptomatic treatment, sometimes with antidotes.

In the Netherlands, hardly any intoxication is fatal, when the patient arrives in the hospital in time, or euthanasia took place on purpose.

The analysis of motivational systems underlying temporal organisation in animal behaviour has relied primarily on two conceptual functional frameworks: Homeostasis and biological clocks. Homeostasis is one of the most general and influential concepts in physiology. Walter Cannon introduced homeostasis as a universal regulatory principle which animals employ to maintain constancy of their ‘internal milieu’ in the face of challenges and perturbations from the external environment. Cannon spoke of “The Wisdom of the Body”, the collective of responses designed to defend the ideal internal state against those perturbations.

Since some years it has become evident that objective disturbances can be found in patients suffering from personality disorders. Research findings from earlier date already demonstrated low levels of 5-hydroxyindoleacetic acid in the cerebrospinal fluid, especially in patients with personality disorders, under exclusion of depressive features. Furthermore, data have been collected on the correlation between a hyposerotonergic state and disturbances in aggression and impulse control in a variety of syndromes such as automutilation, bulimia nervosa, suicide attempts and various states of drug abuse.

However, psychopharmacological research in personality disorders is rare and to date mainly patients with borderline and schizotypical personality disorders have been studied. It is quite remarkable for this area to find more review articles than original contributions based on the results of clinical trials. A great variety of recommendations for pharmacotherapy in these patients exists in literature, among which treatment with carbamazepine, lithium, low-dose neuroleptics, tricyclic antidepressants and serotonin uptake inhibitors. In this article we will analyze the research methodology and the results of clinical trials forming the base for pharmacotherapeutic treatment recommendations.

Only the results of well-controlled studies will be reviewed.

Huntington's disease (HD) is an autosomal dominant disorder of the central nervous system, characterised by neurological, cognitive and psychiatric pathology. Recently the causative genetic defect was discovered. We present a retrospective study of 59 HD patients, investigating correlations between molecular and clinical data.

The correlation between CAG-repeatlength and age at onset is confirmed. No correlations between this biological marker and other clinical features are found (symptoms at onset, mode of progression of the disease).

The consequences of these findings for predictive testing are discussed. Furthermore, a short overview of the predictive testing procedure in the Center for Human Genetics in Leuven (Belgium) is given.

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.

Risperidone (Risperdal®) is a recently developed antipsychotic drug with the combination of serotonin-5HT2A-and dopamine-D2-antagonism (SDA). In patients with schizophrenia, risperidone reduces positive symptoms at least equally effective as haloperidol, however, risperidone has a reduced propensity for the induction of extrapyramidal symptoms.

In addition, available evidence indicates that risperidone may be an effective treatment for negative symptoms. The optimum daily dose range is between 4 and 8 mgfor most patients. In this review article, risperidone is compared with some other (classical and atypical) neuroleptics. In addition, the pharmacological and pharmacokinetic properties of risperidone are reviewed.

The adult human typically exhibits a monophasic sleep-wake cycle, i.e., remains awake and alert for approximately 16 hours and then sleeps for 8 hours. Recent experiments have provided new insights in the role of the endogenous circadian pacemaker in this consolidation of sleep and wakefulness.

Sleep deprivation studies had shown previously that sleepiness and alertness are co-determined by a process which keeps track of the history of sleep and wakefulness and the circadian pacemaker, which keeps track of time. During every day life and during sleep deprivation both processes change simultaneously and their relative contribution to alertness and sleep propensity cannot be assessed under these conditions.

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.