Schizophrenia
One of the most reliable sources is National Institute for Health and Clinical Excellence.
http://www.nice.org.uk/nicemedia/pdf/CG82FullGuideline.pdf
This guideline fully describes the true state of our knowledge today! For example: Look up page 21-22, where the Possible causes of schizophrenia is described. It says:
"The possible causes of schizophrenia are not well understood. Research has attempted to determine the causal role of biological, psychological and social factors. The evidence does not point to any single cause. Increasingly, it is thought that schizophrenia and related psychoses result instead from a complex interaction of multiple factors (Broome et al., 2005; Garety et al., 2007). Much of the research evidence on the aetiology of schizophrenia is consistent with the long-standing ‘stress-vulnerability‘model (Nuechterlein & Dawson, 1984). This paradigm suggests that individuals possess different levels of vulnerability to schizophrenia, which are determined by a combination of biological, social and psychological factors. It is proposed that vulnerability results in the development of problems only when environmental stressors are present. If there is great vulnerability, relatively low levels of stress might be sufficient to cause problems. If there is less vulnerability, problems develop only with higher levels of stress. The model is consistent with a wide variety of putative causes of the disorder, as well as the differential relapse and readmission rates observed among people with schizophrenia. Recent research has therefore attempted to specify more precisely the nature of any vulnerability and of types of environmental stress. This includes biological hypotheses about brain biochemistry and pathology (Broome et al., 2005), and attempts to identify genes that confer susceptibility (Craddock et al., 2005). Biochemical theories have centred mainly on the ‘dopamine hypothesis‘, for which there is enduring support (Kapur, 2003). This argues that schizophrenia might be related to problems in the regulation of the neurotransmitter dopamine in the pre-frontal cortex. Psychological factors can be divided into problems with basic cognitive functions, such as learning, attention, memory, or planning, and biases in emotional and reasoning processes. Problems in cognitive function are related to research in brain structure and function, while emotional processes may be linked to social factors. Studies of psychological factors thus provide a bridge between biological and social theories. Both types of psychological factor have been implicated in the development of symptoms of schizophrenia (Frith, 1992; Gray et al., 1991; Green, 1992; Hemsley 1993; Garety et al., 2001; 2007). Recently depression and anxiety, which were previously considered unimportant by researchers, have been found to contribute to the symptoms of schizophrenia (Freeman & Garety, 2003; Birchwood, 2003; Krabbendam & van Os, 2005). Recently there has been a resurgence of interest in investigating social and environmental factors. Evidence has been accumulating to suggest that urban birth and rearing, social adversity and trauma, heavy cannabis use, migration and stressful life events all increase the risk of schizophrenia (Arseneault et al., 2004; Bebbington et al., 2004; Moore et al., 2007; Read et al., 2005; van Os et al., 2005). There is now consistent evidence that migrant populations experience raised rates and especially high rates have been found among certain minority ethnic groups (Cantor-Graae & Selten, 2005; Kirkbride et al., 2006). It is thought that this is most likely related to the high rates of social adversity and family disruption experienced by some migrant populations (Selten & Cantor-Graae, 2005; Fearon et al., 2006)."