Kraepelin revisited: schizophrenia from degeneration to failed regeneration

One hundred years after its conceptual definition as 'Dementia Praecox' by Emil Kraepelin, schizophrenia is still a serious psychiatric illness that affects young adults and leads to disability in at least half of patients. The key treatment issue is partial or non-response, especially of negative symptoms. The illness is also associated with different degrees of cognitive dysfunction, particularly in verbal and working memory; the resulting functional impairment may lead to unemployment and an inability to maintain stable relationships. Patients' cognitive dysfunction led Kraepelin to the assumption that schizophrenia is a form of juvenile dementia caused by a degenerative process of the human brain. Postmortem studies and a plethora of imaging studies do not support the notion of a degenerative process, but such a process is supported by the recently published, largest genome-wide association study on schizophrenia. More than a 100 hits were described, converging on pathways that have a significant role in dopamine metabolism in immune modulation, calcium signalling and synaptic plasticity. This review suggests that research should focus on animal models based on risk genes like transcription factor 4 and study the effects of exposure to environmental stressors relevant for schizophrenia. The use of relevant end points like pre-pulse inhibition or cognitive dysfunction will allow us to gain an understanding of the molecular pathways in schizophrenia and consequently result in improved treatment options, especially for the disabling aspects of this illness.

The effects of physical exercise in schizophrenia and affective disorders

Affective and non-affective psychoses are severe and frequent psychiatric disorders. Amongst others, they not only have a profound impact on affected individuals through their symptomatology, but also regarding cognition, brain structure and function. Cognitive impairment influences patients' quality of life as well as their ability to work and being employed. While exercise therapy has been implemented in the treatment of psychiatric conditions since the days of Kraepelin and Bleuler, the underlying mechanisms have never been systematically studied. Since the early 1990s, studies emerged examining the effect of physical exercise in animal models, revealing stimulation of neurogenesis, synaptogenesis and neurotransmission. Based on that body of work, clinical studies have been carried out in both healthy humans and in patient populations. These studies differ with regard to homogenous study samples, sample size, type and duration of exercise, outcome variables and measurement techniques. Based on their review, we draw conclusions regarding recommendations for future research strategies showing that modern therapeutic approaches should include physical exercise as part of a multimodal intervention programme to improve psychopathology and cognitive symptoms in schizophrenia and affective disorders.