Patients May Lose Awareness of Memory Loss Years before Onset of Dementia
Patients who will develop dementia may start to become less aware of their memory problems years before the disease actually sets in, according to a new study.
“Our main finding was that unawareness of memory impairment is part of the natural history of dementia in late life rather than a symptom experienced by a few affected persons,” says lead study author Robert S. Wilson, PhD, senior neuropsychologist of the Rush Alzheimer’s Disease Center in Chicago. “On average, awareness began to decline 2.6 years before dementia was diagnosed.”
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While the majority of studies of memory unawareness in dementia have focused on people who have already been diagnosed, this study began following older adults before they showed signs of the disease.
Wilson and his colleagues conducted analyses of nearly 2,100 participants involved in 3 ongoing studies that each followed older adults for more than a decade. At baseline, participants were an average age of 76 years old and showed no signs of memory or cognitive impairment.
Participants completed annual evaluations of their memory and cognitive abilities, and researchers also asked them how often they had trouble remembering things and how they would rate their memory compared to 10 years earlier.
During the study, 239 patients were diagnosed with dementia—their memory awareness was stable at first and then began to decline rapidly about 2 to 3 years before dementia onset.
“Declines in awareness (of memory loss in dementia) tended to occur earlier in younger than older patients,” Wilson says. “We think this might be because memory impairment is so common among the oldest old.”
While there were differences in when the declines began and how quickly they progressed, practically all of the patients were unaware of their memory problems at some point in the course of their dementia.
Investigators also examined the brains of 385 participants who died during the course of the study, inspecting them for 7 types of neurological changes common in dementia. “We found that the presence of large strokes and higher levels of pathologies associated with Alzheimer’s disease and ALS were associated with more rapid decline in awareness of memory impairment,” Wilson says.
They identified 3 dementia-related pathologies that appeared to be associated with rapid decline in memory awareness:
• tau proteins or tangles.
• infarcts, or areas of brain damage.
• changes in the protein TDP-43.
When these pathologies weren’t present, the researchers found no evidence of decline in awareness of memory loss.
Wilson says these findings should help practitioners and family members better understand the behavior of people with dementia and help with its clinical diagnosis.
“This study underscores the importance of family members looking for help from doctors and doctors getting information from friends or family when making decisions about whether a person has dementia, since people may be unable to give reliable reports about the history of their own memory and thinking abilities,” he says.
—Colleen Mullarkey
Reference
Wilson RS, Boyle PA, Yu L, Barnes LL, Sytsma J, Buchman AS, et al. Temporal course and pathologic basis of unawareness of memory loss in dementia. Neurology. 26 Aug 2015. [Epub ahead of print].