This study examines the relationship between various possible precipitating events and the onset of unipolar depressive illness in 100 patients. The precipitating factors studied were: (1) deprivation prior to age 16 as a result of loss of parents by death, separation or divorce; (2) personal losses through death in the year before admission; (3) threatened personal losses; and (4) physical illness in the preceding six months. Patients whose depressive illness started before age 40 had a significantly higher incidence of real or threatened personal losses than did later-onset depressives (after 40). Twelve patients claimed a personal loss preceding the onset of depressive symptoms. Using 51 well relatives of the patients, matched for age and sex as controls, two claimed a similar type of personal loss. The difference between the two incidences, patient 12% and control of 3.9%, is not statistically significant.
Cadoret RJ, Winokur G, Dorzab J, Baker M. Depressive Disease: Life Events and Onset of Illness. Arch Gen Psychiatry. 1972;26(2):133-136. doi:10.1001/archpsyc.1972.01750200037008