Everyday “senior moments” — forgetting where you left your car keys, for example, or the name of a friend of a friend — are not necessarily something to worry about, according to a new study.

The time to be concerned about such sudden lapses in memory (which affect people of all ages) is when you stop noticing them, the study’s findings suggest. 

And that warning sign — forgetting that you have forgotten — starts to occur two to three years before the onset of dementia, the findings also indicate.

“The results suggest that declining awareness of memory impairment is an essentially inevitable manifestation of late-life dementia,” write the study’s authors.

The study appeared last week in the journal Neurology, which is published by the Minnesota-based American Academy of Neurology. The research was led by Robert S. Wilson, a neuropsychologist at Rush University Medical Center in Chicago.

Study details

For the study, Wilson and his colleagues analyzed data collected from 2,092 people participating in three ongoing studies: the Religious Orders Study, the Rush Memory and Aging Project and the Minority Aging Research Study. The mean age of the participants was 76 at the start of the study, and none entered the study with signs of memory problems or other cognitive impairments.

The participants were followed for just under 11 years. Each year, they underwent a clinical exam as well as a battery of memory and cognitive tests. They were also asked how often they had trouble remembering things and how they would rate their memory compared to what it was 10 years earlier.

During the 10-plus years of the study, 239 participants (about 10 percent of the total group) were diagnosed with dementia. An analysis of the data on the participants who developed dementia revealed that their memory awareness was stable until it began to sharply drop 2.6 years (on average) before diagnosis.

“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,” said Wilson in a statement released with the study.

Autopsies were also conducted on the brains of 385 participants who died during the study. The researchers found that people who had experienced a rapid decline in memory awareness were more likely to have protein tangles, infarcts (dead brain tissue resulting from a lack of blood) and other dementia-associated signs of neural damage.

Limitations and implications

This study has several strengths, including a large number of participants and a relatively long follow-up period. But the ongoing studies from which the participants were drawn involved specific populations that may or may not be representative of everyone — thus the need, say the researchers, for ‘replicating these results in other cohorts.”

Still, the findings are interesting — and reassuring, perhaps, for anybody who worries about their “senior moments.”

Yet the findings also “underscore 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,” said Wilson, “since people may be unable to give reliable reports about the history of their own memory and thinking abilities.”

Although the study was funded in part by public money from the National Institute on Aging, it is behind a paywall on the Neurology website.