Memory declines faster in years closest to death
Two new studies published in the April 4 online issue of Neurology, the medical journal of the American Academy of Neurology, suggest that a person’s memory declines at a faster rate in the last two-and-a-half years of life than at any other time after memory problems first begin. The second study shows that keeping mentally fit through board games or reading may be the best way to preserve memory during late life. Both studies were conducted by researchers at Rush University Medical Center.
“In our first study, we used the end of life as a reference point for research on memory decline rather than birth or the start of the study,” said study author Robert S. Wilson, PhD, study author and neuropsychologist at Rush University Medical Center in Chicago.
For the study, 174 Catholic priests, nuns and monks without memory problems had their memory tested yearly for six to 15 years before death. After death, scientists examined their brains for hallmarks of Alzheimer’s disease called plaques and tangles.
The study found that at an average of about two-and-a-half years before death, different memory and thinking abilities tended to decline together at rates that were 8 to 17 times faster than before this terminal period. Higher levels of plaques and tangles were linked to an earlier onset of this terminal period but not to rate of memory decline during it.
The second study, also conducted by Wilson, showed that keeping mentally fit through board games or reading may be the best way to preserve memory during late life.
The study, which focused on mental activities, involved 1,076 people with an average age of 80 who were free of dementia. Participants underwent yearly memory exams for about five years. They reported how often they read the newspaper, wrote letters, visited a library and played board games such as chess or checkers. Frequency of these mental activities was rated on a scale of one to five, one meaning once a year or less and five representing every day or almost every day.
Robert Wilson found that the characteristic plaques and tangles of Alzheimer’s disease (which occur before the disease is diagnosable) are not to blame for the fast rate of the decline. Alzheimer’s tangles and plaques were associated with the decline starting earlier, but not with it going faster. That points to another culprit for the memory problems.
“The findings suggest that the changes in mental abilities during the two to three years before death are not driven directly by processes related to Alzheimer’s disease, but instead that the memory and other cognitive decline may involve some biological changes in the brain specific to the end of life,” Oregon Health and Science University professor Hiroko Dodge, who was not involved in the study, wrote in an editorial accompanying the new paper. “The study by Wilson and his co-authors deepens our understanding of terminal cognitive decline.”
“The results suggest a cause and effect relationship: that being mentally active leads to better cognitive health in old age,” said Wilson.
The results showed that people’s participation in mentally stimulating activities and their mental functioning declined at similar rates over the years. The researchers also found that they could predict participants’ level of cognitive functioning by looking at their level of mental activity the year before but that level of cognitive functioning did not predict later mental activity.
Cognitive declines usually begin in a person’s early 30s and are primarily observed in four areas:
(1) Attention or the ability to concentrate on one thing despite other things going on around you. Thus, as we get older we become more distractible.
(2) Working-memory or the ability to hold information in mind for a brief period of time to perform some task (such as following driving instructions or figuring out how much to tip). Thus, as we get older we’re more easily confused as information is not always available when we need it.
(3) Long-term memory, especially recollective memory for details such as names, locations, and who told us something. Thus, as we get older we become more forgetful.
(4) Information-processing speed or how quickly we perceive, think, and act. Thus, as we get older our thoughts and actions get slower.
Some researchers view the above problems as symptoms of a more general age-related decline in cognitive control, the ability to flexibly implement one’s goals in the face of distraction.
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The studies were supported by the National Institute on Aging and the Illinois Department of Health.
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Nancy DiFiore
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Rush University Medical Center