ORLANDO—Elderly patients with acute depression who show deficits on brief structured tests of memory and executive function have a high risk for developing Alzheimer’s disease within the next few years, according to research presented at the 2014 Annual Meeting of the American Association for Geriatric Psychiatry (AAGP).
“Our study suggests that late-life depression with documented memory and executive function impairment is just the tip of a bad neuropsychiatric iceberg and that there is more to come,” said principal investigator David C. Steffens, MD.
David C. Steffens, MD
It is unclear whether depression in the elderly is a risk factor for dementia or a prodrome of the disorder. The two possibilities are not mutually exclusive, according to Dr. Steffens, Professor and Chairman of the Psychiatry Department at the University of Connecticut in Farmington.
The subsequent course of elderly patients with depression and comorbid mild cognitive impairment is highly variable, as illustrated in a study in which Dr. Steffens and his colleagues followed 69 such patients for two years. Seventeen patients became cognitively unimpaired, six developed subsyndromal Alzheimer’s disease, six had possible Alzheimer’s disease, two had probable Alzheimer’s, two had dementia of undetermined etiology, 13 still met criteria for mild cognitive impairment without dementia, and 23 had cognitive impairment, which during follow-up became attributable to a more specific cause, such as cerebrovascular disease or another medical condition.
To find a means of predicting which patients with late-life major depressive disorder are most likely to develop dementia, the investigators used baseline neuropsychologic testing. Dr. Steffens presented recently published highlights of the Neurocognitive Outcomes of Depression in the Elderly (NCODE) trial, a longitudinal outpatient depression treatment study.
In this phase of NCODE, 179 older adults with acute depression but without dementia underwent baseline neuropsychologic testing, received active treatment for their depression, and were followed for a mean of 5.5 years. During follow-up, Dr. Steffens and his coinvestigators diagnosed 30 subjects as having incident dementia and deemed the other 149 cognitively normal.
Completing an extensive battery of neuropsychologic tests can be difficult for an elderly patient with late-life depression. Two of the neuropsychologic tests—the Consortium to Establish a Registry of Alzheimer’s Disease (CERAD) Recognition Memory and the Trail Making Test Part B—proved to be the best predictors of subsequent conversion to dementia.
Focusing on two tests for prognostication is practical in everyday clinical practice. Administering a lengthy battery of neuropsychologic tests, on the other hand, really is not practical, said Dr. Steffens, who is also AAGP president.
In a multivariate analysis, deficits on CERAD Recognition Memory and the Trail Making Test Part B were associated with a 6.8-fold increased risk of developing dementia during follow-up, compared with elderly patients with acute depression who scored in the normal range. The two tests correctly classified 91.6% of NCODE participants, with false-positive and false-negative rates of 5.9% and 8.6%, respectively. “As more and more data accumulate, the field is moving to a point where we can say that as part of our assessment, if you focus on one or two tests, that may actually prognosticate better,” Dr. Steffens said.
—Bruce Jancin