On the clinical significance of reduced executive functions in elderly patients with mental illnesses Research question: Executive functions (EF) show increasing deficits in old age.There are also numerous studies demonstrating the importance of EF in relation to depression, anxiety disorders and post-traumatic stress disorder in older patients. The study presented examined this question in a sample of patients in a psychosomatic clinic who were in middle (< 60years) and older age (≥ 60years) (N = 150) and compared them with a psychologically non-stressed comparison sample (N = 157).The survey instrument used to assess EF was the Trail-Making Test (TMT). The results show age and setting differences, i. e. older as well as mentally ill subjects showed worse results; an interaction effect was also found. Associations of symptoms and EF were found only in the elderly sample, but not in the middle-aged sample. The results show that the importance of impaired executive functions is a clinically relevant variable in psychotherapy of the elderly.