Frontal lobe syndrome reassessed: comparison of patients with lateral or medial frontal brain damage

Examination of mood and behaviour changes after frontal damage may contribu te to understanding the functional role of distinct prefrontal areas in dep ression and anxiety. Depression and anxiety disorders, symptoms, and behavi our were compared in eight patients with single lateral and eight patients with single medial frontal lesions matched for age, sex, race, education, s ocioeconomic status, side, and aetiology of lesion 2 weeks and 3 months aft er brain injury. DSM IV major depressive and generalised anxiety disorders were more frequent in patients with lateral compared with medial lesions at 2 weeks but not at 3 months. At 3 months, however, patients with lateral d amage showed greater severity of depressive symptoms, and greater impairmen t in both activities of daily living and social functioning. At initial eva luation depressed mood and slowness were more frequent, whereas at 3 months slowness, lack of energy, and social unease were more frequent in the late ral than the medial group. Patients with lateral lesions showed greater red uction of emotion and motivation (apathy) during both examinations. Medial frontal injury may fail to produce emotional dysregulation or may inhibit e xperience of mood changes, anxiety, or apathy. Lateral prefrontal damage ma y disrupt mood regulation and drive while leaving intact the ability to exp erience (negative) emotions.