Comorbidity: Psychiatric Comorbidity in Persons With Dementia

The assessment and treatment of psychiatric symptoms in persons with cognitive dysfunction are becoming increasingly important. Prevalence estimates of dementia in the United States range from 5% in those aged 71 to 79 years to 25% to 50% in those 90 or older. Up to 90% of patients with dementia have psychiatric comorbidities.1,2 Physicians who treat patients with dementia must remember that dementia is not merely a problem with memory. The presence of one or more additional cognitive disturbances, including aphasia, apraxia, or agnosia, is required to make the diagnosis according to DSM-IV-TR criteria. Furthermore, some patients may present with changes in personality or deficits in executive function rather than memory impairment, which complicates the initial diagnosis.3 Additional mental and behavioral disturbances often affect patients and caregivers as much as memory deficits and may influence quality of life, the need for institutionalization, mortality, and caregiver burden.2,4,5 This article emphasizes neuropsychiatric disturbances with the greatest prevalence and morbidity in persons with dementia. It also addresses comorbid depressive and anxiety disorders, as well as psychological and behavioral disturbances associated with dementia—psychosis and agitation/aggression.3,6 DEPRESSION Depression affects 20% to 32% of persons with dementia: the prevalence is higher in patients with vascular dementia than in patients with Alzheimer disease (AD).6 Assessing depression in dementia patients poses several challenges. Depressive symptoms can be the initial manifestations of dementia and may fluctuate over time.2,3 Compared with older patients with intact cognition, patients with dementia are more likely to report a diminished ability to concentrate or indecisiveness during a major depressive episode.4 On the other hand, patients with dementia are less likely to report insomnia/hypersomnia, feelings of worthlessness and guilt, or thoughts of death/suicide.4