Early developmental milestones in adult schizophrenia and other psychoses.A 31-year follow-up of the Northern Finland 1966 Birth Cohort

Delayed childhood development may precede adult psychoses. We tested this h ypothesis in a large, general population birth cohort (n = 12 058) followed to age 31 years. The ages at which individuals learned to stand, walk, spe ak, and became potty-trained (bowel control) and dry (bladder control), wer e recorded at a 1-year examination. Psychiatric outcome was ascertained thr ough linkage to a national hospital discharge register. Cumulative incidenc e of DSM-III-R schizophrenia, other psychoses and non-psychotic disorders w ere stratified according to the timing of milestones and compared within th e cohort using internal standardization. 100 cases of DSM-IU-R schizophreni a, 55 other psychoses, and 315 non-psychotic disorders were identified. The ages at learning to stand, walk and become potty-trained were each related to subsequent incidence of schizophrenia and other psychoses. Compared wit h the whole cohort, earlier milestones reduced, and later milestones increa sed, the risk in a linear manner. These developmental effects were not seen for non-psychotic outcomes. The findings support hypotheses regarding psyc hosis as having a developmental dimension with precursors apparent in early life. (C) 2001 Elsevier Science B.V. All rights reserved.