Aerobic exercise and its effects on cognition in schizophrenia.

PURPOSE OF REVIEW: Schizophrenia is a severe neuropsychiatric disorder with incomplete remission because of negative and cognitive symptoms in a large proportion of patients. Antipsychotic medication is successful in modulating positive symptoms, but only to a lower extent negative symptoms including cognitive dysfunction. Therefore, development of innovative add-on treatment is highly needed. In this review, recent evidence from clinical studies reveals effects of aerobic exercise on cognitive deficits in schizophrenia patients. RECENT FINDINGS: First studies and meta-analyses on aerobic exercise in schizophrenia patients have shown effects on positive, negative, and global symptoms and cognitive domains such as global cognition, working memory, and attention. Underlying neurobiological mechanisms such as neuroplasticity-related synaptogenesis and neurogenesis have been identified in animal studies and possibly mediate effects of aerobic exercise on brain structure and function. SUMMARY: Different aspects of methods (e.g., endurance training versus yoga and Tai Chi), length and dose of the intervention, supervision of patients by sports therapists as well as maintenance of cognitive improvement after cessation of training have been raised by previous studies. However, minimal and most effective dosage of the intervention and mechanisms underlying changes in neuroplasticity need to be answered in future basic and large-scale randomized clinical trials.

Disturbed macro-connectivity in schizophrenia linked to oligodendrocyte dysfunction: from structural findings to molecules.

Schizophrenia is a severe psychiatric disorder with multi-factorial characteristics. A number of findings have shown disrupted synaptic connectivity in schizophrenia patients and emerging evidence suggests that this results from dysfunctional oligodendrocytes, the cells responsible for myelinating axons in white matter to promote neuronal conduction. The exact cause of this is not known, although recent imaging and molecular profiling studies of schizophrenia patients have identified changes in white matter tracts connecting multiple brain regions with effects on protein signaling networks involved in the myelination process. Further understanding of oligodendrocyte dysfunction in schizophrenia could lead to identification of novel drug targets for this devastating disease.

The impact of environmental factors in severe psychiatric disorders.

During the last decades, schizophrenia has been regarded as a developmental disorder. The neurodevelopmental hypothesis proposes schizophrenia to be related to genetic and environmental factors leading to abnormal brain development during the pre- or postnatal period. First disease symptoms appear in early adulthood during the synaptic pruning and myelination process. Meta-analyses of structural MRI studies revealing hippocampal volume deficits in first-episode patients and in the longitudinal disease course confirm this hypothesis. Apart from the influence of risk genes in severe psychiatric disorders, environmental factors may also impact brain development during the perinatal period. Several environmental factors such as antenatal maternal virus infections, obstetric complications entailing hypoxia as common factor or stress during neurodevelopment have been identified to play a role in schizophrenia and bipolar disorder, possibly contributing to smaller hippocampal volumes. In major depression, psychosocial stress during the perinatal period or in adulthood is an important trigger. In animal studies, chronic stress or repeated administration of glucocorticoids have been shown to induce degeneration of glucocorticoid-sensitive hippocampal neurons and may contribute to the pathophysiology of affective disorders. Epigenetic mechanisms altering the chromatin structure such as histone acetylation and DNA methylation may mediate effects of environmental factors to transcriptional regulation of specific genes and be a prominent factor in gene-environmental interaction. In animal models, gene-environmental interaction should be investigated more intensely to unravel pathophysiological mechanisms. These findings may lead to new therapeutic strategies influencing epigenetic targets in severe psychiatric disorders.