S-20-01

What is evolutionary psychiatry?

T. Steimer. Clinical Psychopharmacology, Genf, Switzerland

The clinical approach to psychiatric disorders has been mainly phenomenological and empirical. Progress in the understanding of the biological substrates underlying some pathologies (e.g. the neuroendocrine stress system in depression) has led to more theoretical considerations regarding the etiology and physiopathology of mental illness. Animal models of psychiatric disorders, on the other hand, have shown a role for adaptive vs maladaptive responses to environmental and social challenges, and the importance of genetic vs environmental influences during ontogenesis. These findings have been incorporated into the current “biopsychosocial model”. Recently, evolutionary psychiatry has emerged as a new theoretical framework, based on concepts derived from evolutionary theories, also including ethology and sociobiology. It is an attempt to reconsider psychopathology within the context of phylogenesis and alternative adaptative strategies: behaviours have been selected - or retained - for their adaptive value. Although this new way of considering psychiatric diseases is interesting and potentially fruitful, it has to be assessed critically. First, the “evolutionary explanation” may not apply to all kinds of psychiatric diseases, or their individual manifestations. Some of them are more likely the result of dysfunctions which, being of limited prevalence, can be tolerated as part of natural variation. Second, evolutionary theories themselves are open to criticism and, in particular, the “adaptationist” view must be considered with some caution, because adaptation may not be a driving force of evolution. In this Introduction, we will try to give a balanced account of the evolutionary approach to psychiatric syndromes and consider some of its further developments.

S-20-02

A. Langaney. Dpt. of Anthropology and Ecolo, Geneva, Switzerland

S-20-03

Therapeutic implications of Darwinian psychiatry A. Troisi. Dpt. of Neurosciences, Univers, Roma, Italy

Darwinian psychiatry applies the concepts and methods of evolutionary biology to the study of mental disorders. As a new approach to the explanation for the origin of psychopathology, Darwinian psychiatry has attracted much interest among clinical and research psychiatrists. However, its utility in terms of treatment strategies and therapeutic interventions has been repeatedly questioned. The aim of this presentation is to demonstrate that, contrary to this common prejudice, Darwinian psychiatry has relevant therapeutic implications and can contribute to improve treatment strategies in psychotherapy and psychopharmacology. Unlike the biomedical model of mental disorders, Darwinian psychiatry distinguishes between dysfunctional and adaptive symptoms. Dysfunctional symptoms reflect neurobiological damage and their therapeutic elimination (if possible) does not entail any risk for the patient. By contrast, adaptive symptoms are evolved responses that serve the function of limiting or offsetting the adverse consequences of maladaptive circumstances. Symptoms of anxiety and depression may act as alarm signals and may favor the implementation of alternative behavior strategies. The use of drugs or psychological therapies to eliminate these symptoms may diminish suffering but worsen the global condition of the patient, as in the case of antipyretics in infectious diseases. Another important point emerging from a Darwinian approach to psychiatric therapy is that functional outcome is more important than symptom evaluation. In line with an evolutionary perspective, recent research has shown that functional impairment is a core aspect of different psychiatric disorders and that its occurrence is largely independent from symptom severity.

S-20-04

The human nature of animals

J. Koolhaas. Dpt. of Animal Physiology, Uni, Haren, Netherlands

In scientific research, animals are generally used as a model to obtain fundamental insight into human functioning. It is generally accepted that there is a considerable similarity between animals and human beings in physiological processes. However, with respect to behavior and psychology, this correspondence is far less self evident. Although the overt expression of behavior knows large species specific differences, all vertebrates share a number of fundamental mechanisms underlying behavior. A phylogenetically ancient capacity involves the way individuals deal with environmental challenges. Different coping styles can be distinguished and it will be argued that individual differentiation in coping style is fundamental to a wide variety of animal species. Studies on feral populations of rodents, fish and birds show that the differentiation in coping style has an important function not only in the social organization, but also in the evolutionary ecology of the species. Animals with a different coping style differ also in the neurobiological and neuroendocrine mechanisms underlying behavior. These include serotonergic and vasopressinergic neurotransmission and HPA axis reactivity. Some evidence will be presented that these physiological differences may explain the individual vulnerability to stress related disease. At first glance, the physiological and behavioral characteristics of coping styles are similar to human personality or temperament characteristics. However, the question if, and to what level the individual differentiation in coping style reflects the biological basis of human personality or temperament requires an experimental approach that requires a joint search for the human nature in animals as well as the animal nature in humans.