BY THOMAS R. COLLINS
CHICAGO—The median survival time after a dementia diagnosis is the same for younger patients and older patients, according to results of an analysis of a large Dutch memory clinic cohort presented here at the Alzheimer's Association International Conference.
The study, which involved 4,495 patients tracked over 15 years, was prompted by the relatively thin amount of literature on dementia survival, especially in younger patients. The paucity of data on survival can hamper discussions between patients and clinicians, said Hanneke Rhodius-Meester, MD, a clinical geriatrician and researcher at VU Medical Center Alzheimer Center in Amsterdam.
"When they come to us and they receive their diagnosis, often one of the first questions is, 'What comes next? How long do I have to live?'" she said.
The findings were both surprising and discouraging — the hope was that the better overall health condition of the younger patients would mean they would live longer, Dr. Rhodius-Meester said. But that wasn't the case.
Researchers pulled data from participants enrolled in the Amsterdam Dementia Cohort between 2000 and 2014. The average age was 66 years; about 45 percent were female; and the average score on the Mini-Mental Status Examination was 24. Prior to enrollment, patients had subjective cognitive decline, mild cognitive impairment, or dementia diagnosis. Researchers collected patients' mortality data from the Dutch government registry.
The findings revealed mortality differences based on dementia type, with longer median survival for frontotemporal lobar degeneration at 6.4 years, Alzheimer's disease at 6.2 years, vascular dementia at 5.7 years, and dementia with Lewy bodies at 5.1 years. Median survival for more rare dementia causes, such as Creutzfeldt-Jakob disease, was 3.6 years.
The researchers found no differences for patients 65 and younger and those older than 65. In fact, in the older group, median survival increased significantly over the study period, by two years (p<.001). This aligned well with lengthened survival in the general population. However, over the same period, this remained unchanged for the younger group.
"It seems that these older patients benefit from the improved health care: better cardiovascular risk management, more knowledge of a healthy diet," Dr. Rhodius-Meester said. "Things that have improved life expectancy in the general population have affected the older patients positively as well. But the young patients don't seem to benefit from those changes. So we think that these young patients have an even more aggressive and even more resistant neurodegenerative disease, like Alzheimer's disease, that just makes them die independent of how well we take care of them otherwise."
The findings underscore the need for precise diagnoses to optimize treatment and care and counseling, she said.
David S. Knopman, MD, FAAN, professor of neurology at Mayo Clinic in the Rochester, MN, said the findings could be modestly useful to clinicians."These are interesting data and are of some value clinically for counseling patients but especially family caregivers," Dr. Knopman said.
But, he added, while there may be differences by type of dementia, that doesn't change the fact that they all have unfavorable prognoses. "My sense is that mean values in survival in dementia are not that helpful: What I find more helpful when talking to patients is to describe the range that accounts for the majority of patients," he said. "So, for example, in behavior variant FTD (frontotemporal degeneration), some patients — often those who develop ALS — may survive only two to three years, whereas some other patients can survive for more than a decade. This study might have underestimated the longer surviving cases due to the duration of total follow-up."
The figures on younger versus older patients might not matter much in the moment of counseling, Dr. Knopman said. "They don't think about comparisons to other people," he added. "They just want to know about themselves, and the take-home message here is that age doesn't make all that much difference."
Dr. Rhodius-Meester had no disclosures. Dr. Knopman disclosed that he serves on the data and safety monitoring board and receives personal compensation for the DIAN-TU study.
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AAIC Abstract P1-357: Rhodius-Meester H, et al. Median survival in memory clinic cohort is short, even in young onset dementia.