Involutional melancholia refers to manic depressive disorder occuring during old age. Age of first presentation is 50 for women and 55 for men. Early symptoms include weight loss, insomnia, lack of interest in activities, poor concentration and low spirits. They also experience dejection, agitation, nihilistic delusions, hypochondriacal delusions and paranoid features.Ref: Abnormal Psychology By Page Mn page 279; Kaplan & Sadock's Comprehensive Textbook of Psychiatry, 9th edition page 1707.