Diagnostic issues and the nature of the relationship between dementia and depression

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Donald A Davidoff

Harvard Medical School, USA

: Int J Ment Health Psychiatry

Abstract

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There are many questions and conflicting research concerning the nature of the relationship between depression and dementia, i.e., are they coincidental, unidirectionally causal, mutually influencing or do they share a common pathophysiology. Normal and pathological aging will be reviewed with a focus on the differences between crystallized and fluid intelligence. Effects of depression on cognition as individuals age are addressed. Depression primarily impairs reaction time and some executive functions, such as mental flexibility, such that executive functions can appear impaired. There has been no demonstration of a consistent disturbance in memory functioning resulting from depression alone, whereas dementia is characterized by memory loss. Nonetheless memory complaints are ubiquitous amongst the elderly, regardless of whether they are healthy, depressed or dementing. No consistent and agreed upon terminology is apparent throughout the literature on the relationship between dementia and depression, confounding a current understanding. For example, DSM-5 criteria for a diagnosis of depression may currently result in an under-reporting of major depression because elder patients tend demonstrate fewer symptoms and tend to focus on somatic and/ or cognitive complaints rather than on mood issues. Thus, a nosology is proposed to help clarify these issues. Depression confounds the diagnosis of dementia and vice versa. Current research has not provided a definitive understanding of this complex relationship. Recent studies have suggested that the magnitude and trajectory of depressive symptomatology have been underappreciated. Perhaps the single greatest problem in understanding the relationship between dementia and depression is the heterogeneous nature of the illnesses themselves. Clarification can only come when careful specification of each group is made. In effect, apples must be compared with apples and not with oranges.

Biography

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Donald A. Davidoff is the Chief of the Department of Neuropsychology and Director of the Neuropsychology Fellowship Program at the McLean Hospital, Harvard Medical School. He is also an assistant professor in the Department of Psychiatry, Harvard Medical School and Psychologist, McLean Hospital. He founded the Geriatric Neuropsychiatry Unit in 1993 and was its Psychologist- in-Charge for 15 years, retiring from that position to focus on research and the Department of Neuropsychology. He has published numerous papers and book chapters on the diagnosis and management of patients with dementia, treatment resistant affective disorders, optimal aging, the neurocognitive basis of Hoarding Disorder, nonverbal learning disabilities and affective and motivational aspects of memory functioning. He is a sought after speaker for interdisciplinary conferences and has taught courses at the American Psychiatric Association Meetings consistently for the last 15 years. He is an award-winning teacher and has mentored a large number of multi-disciplined professionals including pre- and post-doctoral psychologists and psychiatry residents. He is a member of the core faculty of the Harvard-South Shore Residency Training program and the McLean-MGH Harvard Residency Training Program.

E-mail: ddavidoff@mclean.harvard.edu