Behavioral and psychological symptoms of dementia and bipolar spectrum disorders: review of the evidence of a relationship and treatment implications.

Dementia is a neuropsychiatric disorder characterized by cognitive impairment and behavioral disturbances. The behavioral and psychological symptoms of dementia (BPSD) are common, contributing to caregiver burden and premature institutionalization. Management of BPSD is complex and often needs recourse to psychotropic drugs. Though widely prescribed, there is a lack of consensus concerning their use, and serious side effects are frequent. This is particularly the case with antidepressant treatment based on the assumption that BPSD is depressive in nature. A better understanding of BPSD etiology could lead to better management strategies. We submit that some BPSD could be the consequence of both dementia and an undiagnosed comorbid bipolar spectrum disorder, or a pre-existing bipolar diathesis pathoplastically altering the clinical expression of dementia. The existence of such a relationship is based on clinical observation, as far as the high frequency of bipolar spectrum disorders in the general population, with a prevalence estimated to be between 5.4% and 8.3%, and the psychopathological similarities between BPSD and mood disorder episodes in bipolar illness. We will review the concept of the bipolar spectrum and explain BPSD before proposing clinical pointers of a possible bipolar spectrum contaminating the phenomenology of dementia, which could lead to the targeted prescription of mood-stabilizing agents in lieu of antidepressant monotherapy. These considerations are of heuristic interest in reconceptualizing the origin of the behavioral manifestations of dementia, with important implications for geriatric practice.