Neurodevelopmental and neurodegenerative models of schizophrenia Sample Clauses

Neurodevelopmental and neurodegenerative models of schizophrenia. The understanding of schizophrenia's etiopathology and natural course, which shape its clinical presentation and guide its treatment, can be viewed under two different perspectives: the neurodevelopmental and neurodegenerative models. The neurodevelopmental model of schizophrenia posits that this disease is the outcome of abnormalities in maturational processes, occurring in the brain long before the onset of symptoms, caused by genetic and environmental factors (Xxxxxxxxx et al. 2012, Xxxxxx and Xxxxx 1987, Xxxxxxxxxx 1987). Patients show a neurodevelopmental lag, gradually falling behind, in cognitive ability, probably until early adulthood (Xxxxxxxxxxx et al. 2010). In the neurodevelopmental model, genetic liability to psychosis plays a central role, particularly those genes involved in brain development. In order to unravel the complex genetics of psychiatric disorders, the concept of endophenotypes has been construed (Xxxxx and Xxxxxx 2014, Xxxxx et al. 2014, Xxxxxxx and Xxxxx 2010, Xxxxxxxx et al. 2007, Xxxxxx and Xxxxxx 2006, Xxxxxxxxx and Xxxxx 2003). Endophenotypes are disease associated objective measures, including neurophysiological, neuroanatomical, biochemical, endocrinological and neuropsychological parameters. They should reflect the action of susceptibility genes more directly than the disease phenotypical expression, increasing the power to identify those genes and also to understand the mechanisms whereby they influence psychiatric disorders. The criteria for evaluating a potential endophenotype are established, with some variations between authors. The trait should be associated with the disorder in the general population, be more prevalent in unaffected relatives of affected individuals than in the general population, co-segregate with the disease in families, be heritable, be reliably measured, be stable and state-independent (i.e. it should be present in affected individuals even outside periods of acute illness or symptom exacerbation), its measurement should be non-invasive and economically feasible. This approach has been extensively applied to schizophrenia (Xxxxx et al. 2009, Xxxxx et al. 2007) with large ongoing multicentre studies (Xxxxxxxxx et al. 2013, Xxxxxxx et al. 2007). With a different focus, the classic Kraepelin model of schizophrenia stressed that neurodegenerative changes take place after the onset of symptoms, with gradual decline in brain, cognitive and social functioning (Xxxxxxxxx 1999). It has been argued that ...