Objective: The aim of the study was to investigate whether patients with affective disorder have increased risk of developing dementia compared to other groups of psychiatric patients and compared to the general population.
Method: In the Danish psychiatric central register, 3363 patients with unipolar affective disorder, 518 patients with bipolar affective disorder, 1025 schizophrenic and 8946 neurotic patients were identified according to the diagnosis at the first ever discharge from psychiatric hospital during the period from 1970 to 1974. The rate of discharge diagnosis of dementia on readmission was estimated during 21 years of follow-up. In addition, the rates were compared with the rates for admission to psychiatric hospitals with a discharge diagnosis of dementia for the total Danish population.
Results: Patients with unipolar and with bipolar affective disorder had a greater risk of receiving a diagnosis of dementia than patients with schizophrenia and those with neurosis. All groups of patients had a higher risk of being given a diagnosis of dementia than gender- and age-matched samples of the general population.
Conclusion: Patients with affective disorder appear to be at increased risk of developing dementia.