Systematic review on the role of neurocognitive deficits in first-degree relatives of schizophrenic patients.

Aim: To systematically review studies exploring cognitive deficits in first-degree relatives of schizophrenic patients as putative indicators of vulnerability for schizophrenia and identifying if some dysfunction may represent endophenotypic features with genetic liability to the disorder. Methods: Studies focusing on cognitive performances of first-degree relatives of schizophrenic patients within three neuropsychological domains (i.e., attention, memory and executive functions) were included. Searches included MedLine, Embase, PsychINFO, and bibliographies. Results: No clear-cut conclusions can be drawn from the published literature on the topic, since results of reviewed studies were biased by a number of limitations (e.g., low sample sizes, heterogeneity of samples, use of different assessment measures). However, some specific deficits in each of the investigated domains have been reported in both schizophrenic patients and, to a lesser degree, in their first degree relatives, thus suggesting that neurocognitive functions may be considered putative indicators of illness vulnerability. Conclusions: Further evidences are needed to obtain definitive conclusion on the role of neuropsychological functions of first-degree relatives of schizophrenic patients as a marker of illness vulnerability. Future studies should adopt more rigorous research methods and more specific and sophisticated measures of cognitive functions.