Before dementia onset, people lose awareness that their memory is failing

By John Murphy, MDLinx
Published January 6, 2016

Key Takeaways

People who develop dementia begin to lose awareness of their memory impairment about 2 to 3 years before the actual onset of dementia, according to a study published in the August 26, 2015, online issue of Neurology. The researchers also found that this memory impairment is associated with several dementia-related brain pathologies that were evident postmortem.

“Our findings suggest that unawareness of one’s memory problems is an inevitable feature of late-life dementia, driven by a buildup of dementia-related changes in the brain,” said study author Robert S. Wilson, PhD, senior neuropsychologist of the Rush Alzheimer's Disease Center Rush at University Medical Center in Chicago, IL. “Lack of awareness of memory loss is common in dementia, but we haven’t known much about how common it is, when it develops, or why some people seem more affected than others.”

This investigation was novel because it began following people before they had any memory or cognitive impairment. The study began with an analysis of 2,092 older adults (average age 76) from 3 longitudinal clinical-pathologic cohort studies who had no memory or cognitive impairment at baseline. Subjects were given annual evaluations for dementia plus self-rating and performance testing of memory.

From this larger group, a subset of 239 people were diagnosed with dementia during the study. Their awareness of memory was stable until an average of 2.6 years before the onset of dementia, at which point their memory awareness declined rapidly.

“Although there were individual differences in when the unawareness started and how fast it progressed, virtually everyone had a lack of awareness of their memory problems at some point in the disease,” Dr. Wilson said.

Unexpectedly, memory unawareness began earlier in younger people than in older people. This may be because older people were more likely to expect memory loss as a normal part of aging, the researchers suggested.

The researchers also performed postmortem neuropathologic examinations of the brains of 385 participants who died during the course of the study. They found 3 dementia-related pathologies related to the rapid decline in memory awareness: tau tangles, gross cerebral infarcts, and transactive response DNA-binding protein 43 (TDP-43) pathology. As those brain changes occur and build up, affected people lose awareness that their memory is failing, researchers concluded.

“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,” Dr. Wilson said.

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