Predisposition to Schizophrenia: An Update of Current Understanding.

Within the field of mental health, the concept of predisposition or that of being "at risk" has been properly addressed by Mrazek and Haggarty. This period prior to clear diagnosis of psychosis has been referred by several names like 'premorbid' phase, at-risk individuals, predisposed individuals, prodromal phase, etc. The premorbid phase is perhaps the most debated term in this list because this term suggests that the morbidity arises only in the overt illness phase. However, evidences arising from several different lines of observations suggest that this may not be the case. In spite of the fact that it has been generally accepted that the prodromal phase precedes the clinical phase, identification of this phase remains a challenge. The real challenge in identifying the onset of the prepsychotic phase is the differentiation of 'normal' experiences from these 'abnormal' experiences. Much fewer studies have been conducted for the assessment of cognitive functions in prodromal phase or predisposed phases of schizophrenia. Cognitive deficits, particularly in memory and attentional functions, are among the most extensively documented aspects of psychosis. Regarding the somatosensory abnormalities in the high-risk individuals, so far there has been only one study conducted which involved somatosensory evoked potentials in these patients.