Seasonal variations in depression and osteoarthritis.

Seasonal variations in consultations for depression and osteoarthritis were discovered in the 1980 morbidity data of five London practices with a total of 32,524 patients. Depression showed a bimodal pattern similar to that described from hospital data and national suicide statistics, but not previously recorded from general practice. Osteoarthritis also showed a bimodal pattern, with peaks in spring and autumn; this came as a surprise and needs confirmation from other studies. It may reflect the known tendency of rheumatic symptoms to become worse when relative humidity and other climatic variables are at their most changeable.The number of patients recorded in the year as having both osteoarthritis and depression was significantly smaller than would have been expected by chance. This finding is probably due to selective attention in the consultation, since it is unlikely that one condition protects a patient from getting the other.