Causes of Psychosis


Why do many psychiatric disorders
emerge during adolescence?

Tomáš Paus, Matcheri Keshavan and Jay N. Giedd

The peak age of onset for many psychiatric disorders is adolescence, a time of remarkable physical and behavioral changes. The processes in the brain that underlie these behavioral changes have been the subject of recent investigations. What do we know about the maturation of the human brain during adolescence? Do structural changes in the cerebral cortex reflect synaptic pruning? Are increases in white-matter volume driven by myelination? Is the adolescent brain more or less sensitive to reward? Finding answers to these questions might enable us to further our understanding of mental health during adolescence.

Analogous to hallucinations produced by sensory deafferentation, such as phantom limb, the SDA hypothesis assumes that high levels of social withdrawal/isolation in vulnerable individuals prompt social cognition programs to produce spurious social meaning in the form of complex, emotionally compelling hallucinations and delusions representing other persons or agents.

The Social Defeat Hypothesis of Schizophrenia: An Update

Jean-Paul Selten, Elsje van der Ven, Bart P. F. Rutten, and Elizabeth Cantor-Graae

The Social Defeat hypothesis posits that SD (i.e., the negative experience of
being excluded from the majority group) is the common denominator of 5 major schizophrenia risk factors: urban upbringing, migration, childhood trauma, low intelligence, and drug abuse. The purpose of this update of the literature since 2005 is to answer 2 questions: (1) What is the evidence that SD explains the association between schizophrenia and these risk factors? (2) What is the evidence that SD leads to sensitization of the mesolimbic DA system?

Emerging evidence points to a role of the inflammatory process in the pathogenesis of major psychiatric disorders. Accordingly, during the last decade, anti-inflammatory therapeutic approaches have been studied in schizophrenia and depression. Intensive research, however, is necessary in order to clarify whether an immune-related therapy may one day replace treatment with the currently available antidepressants or antipsychotics, at least in subgroups of patients with MD or schizophrenia.