OBJECTIVE: This study was undertaken to examine patients with closed head injuries for the presence of depressive disorders. METHOD: A consecutive series of 66 patients with closed head injuries but no significant spinal cord or other organ system injury were examined by means of a semistructured psychiatric interview. The Hamilton Rating Scale for Depression as well as scales measuring impairment in activities of daily living, intellectual functioning, and social functioning were administered. The patients' CT scans were also examined. RESULTS: Seventeen patients had major depression and two had minor depression. The presence of left dorsolateral frontal lesions and/or left basal ganglia lesions and, to a lesser extent, parietal- occipital and right hemisphere lesions was associated with an increased probability of developing major depression. Compared to the nondepressed group, the group with major depression had a higher frequency of previous psychiatric disorder and showed evidence of poorer social functioning. CONCLUSIONS: Major depression occurs in about one-quarter of patients after traumatic brain injury. This is the same frequency as in other major disorders such as stroke. Major depression appears to be provoked by one or more factors that include poor premorbid social functioning and previous psychiatric disorder or injury to certain critical brain locations.Abstract Teaser