A systemic study of personality features and cognitive processes based on the conception of pathopsychological syndrome has been conducted in patients with the first episode of juvenile endogenous psychosis. The association between characteristics of a pathopsychological syndrome and clinically determined premorbid features has been identified. The highest expression of schizotypal features (reduced selectivity, social perception) and cognitive impairment (motivation, mental activity regulation, adequate self-esteem, emotional reaction to success/failure) were characteristic of a group named "deficit variant of pseudopsychopathy" which contained a large number of passive schizoids. It has been shown that premorbid personality features are most distinct in initial stages of disease ("pathos" factors). "Nosos" factors are implicit and can be only presumably regarded as predictors of disease course.