Am J Psychiatry 1995; 152:862-868
Copyright © 1995 by American Psychiatric Association
A longitudinal follow-up study of seasonal affective disorder
K Sakamoto, S Nakadaira, K Kamo, T Kamo and K Takahashi
Department of Psychiatry, Tokyo Women's Medical College, Japan.
OBJECTIVE: The purposes of this study were to evaluate the long-term
stability of a seasonal pattern of recurrent depression, identify possible
factors associated with alteration of the seasonal pattern, and determine
whether atypical vegetative symptoms during early seasonal depressive
episodes predict future seasonal relapses. METHOD: The subjects were 41
patients satisfying the criteria used in the Japanese multicenter study of
seasonal affective disorder who were consistently treated at the same
outpatient clinic. Their longitudinal courses were evaluated by using case
records and the Schedule for Affective Disorder and
Schizophrenia--Life-time Version; the mean follow-up period was 10.4 years.
RESULTS: Nine subjects (22.0%) consistently showed a fall-winter pattern of
recurrence throughout follow-up. Seventeen patients with an initial
fall-winter pattern subsequently tended to shift seasons or show less
seasonality. This alteration in pattern was possibly associated with
antidepressant therapy or life events. Eleven patients with an initial
diagnosis of nonseasonal affective disorder subsequently developed seasonal
affective disorder; no specific factors were associated with this change.
Atypical vegetative symptoms were significantly more common in patients
with stable seasonal patterns of recurrence than in those who lost
seasonality. CONCLUSIONS: Although seasonal affective disorder appeared to
be altered by antidepressant treatment, the presence of a core group of
patients with a consistent seasonal pattern of recurrent depression
suggests the validity of seasonal affective disorder as a distinct subtype
of recurrent affective illness. The findings also suggest that atypical
vegetative symptoms during early seasonal depressive episodes predict the
subsequent seasonality of depression.
