Depression and dementia are the most frequent mental disorders at senior age. It is assumed that long-term depressions grow into dementia and the relationship between both syndromes has been discussed. The purpose of our study was to establish whether there exists mutual relationship between dementia and depression and whether depression resistant to therapy is a risk factor for dementia development.

25 patients who suffered prolonged phases of depression resistant to therapy were included and monitored for two years. Their average age was 75.4 years (range 65 to 88). The diagnosis of the group was as follows: 11 patients suffered from periodical depressive disorder, 7 patients from depressive phase, 1 patient from bipolar affective disorder and 6 patients from organic depressive disorder. The patients met the diagnostic criteria of severe depression according to ICD-10, the depression grade was assessed by the Geriatric Depression Scale by Yessavage. The diagnosis of dementia was based on clinical examination, CT of the brain, cognitive functions were assessed using the MMSE test.

11 patients of the 25 observed persons with chronified depression symptoms passed into dementia in the course of 2 years. They were 4 patients suffering from periodical depressive disorder, 4 patients with depressive phase and 3 patients with organic depressive disorder.

Our study implies that the development of dementia in depressive patients is significantly more frequent than in non-depressive persons of comparable age. Chronic depression resistant to therapy represents a risk factor for the development of dementia.