Continuity of formal thought disorder from childhood to adulthood in a high-risk sample.

Within a longitudinal prospective study of children of schizophrenic mothers, premorbid, childhood levels of formal thought disorder correlated positively with measures of formal thought disorder obtained in adulthood. It is therefore concluded that schizophrenic symptomatology develops by gradual accretion and that schizophrenia is not a sudden, unexpected disease. Orthogonal factor analysis of formal thought disorder measures obtained in adulthood revealed two factors: one reflecting vague and drifting thinking, and the second relating to the richness of speech.