March 31, 2015
A new analysis from researchers at the Mayo Clinic in Minnesota found various factors that put older adults at risk of developing serious memory problems in old age. Among the most important predictors was, not surprisingly, scoring poorly on a memory test. But non-memory factors like having diabetes or being mentally agitated also significantly increased risk.
For the study, the researchers looked at 1,449 men and women in their 70s and 80s who were living in Olmsted County, Minnesota. All were free of memory problems or dementia at the start of the study.
The study participants were given regular memory and thinking tests, as well as mental health assessments, over a period of about five years. The researchers looked for signs of mild cognitive impairment, or MCI, a form of memory loss that can precede the onset of Alzheimer’s and other forms of dementia. During the study period, they identified 401 participants who developed signs of MCI.
The researchers also combed the participants’ medical charts for other factors that may increase dementia risk, including years of schooling, a history of diabetes, and whether participants smoked or drank alcohol.
After analyzing the data, the researchers identified a list of factors that increase the risk of developing mild cognitive impairment. “Our goal was to identify memory issues at the earliest possible stages,” said Dr. Ronald C. Petersen, an author of the study, which was published in the journal Neurology. “Understanding what factors can help us predict who will develop this initial stage of memory and thinking problems, called mild cognitive impairment, is crucial, because people with MCI have an increased risk of developing dementia.”
From the list, they created a scoring system for factors that increase the risk of MCI, and potential subsequent Alzheimer’s disease. Factors were assigned a score based on how much they contributed to the risk of developing thinking problems. For example, being diagnosed with diabetes before age 75 increased the risk score by 14 points, while having 12 or fewer years of education increased the risk by just 2 points. Scoring poorly on a memory exam was, not surprisingly, a very strong predictor of serious memory problems, with scores ranging from 29 to 38 points.
Having a mental health evaluation that indicated agitation, a heightened state of anxiety, was also a strong predictor of developing serious memory problems (14 points). Apathy (5 points) and ordinary anxiety (5 points) were weaker predictors of memory problems, but significant nevertheless. The researchers said that it was uncertain whether some of these mental health problems developed or worsened as a result of incipient memory problems.
Other factors that increased mild cognitive impairment risk were subjective concerns about memory problems (4 points), having a drinking problem (2 points), having had a stroke (2 points) or having a heart rhythm disorder known as atrial fibrillation, or A-fib (2 points).
Certain factors were predictive in one sex, but not the other. In men, having a slow walking gait was a significant risk factor (9 points), as was being widowed or never married (9 points), being obese (4 points) or being depressed (3 points). In women, having high cholesterol levels in midlife was a fairly strong predictor (6 points).
The researchers also tested participants for the presence of the APOE-E4 gene, which is carried by about 10 to 15 percent of the general population. People who have this gene are at increased risk of developing Alzheimer’s, although many people who carry the gene never develop the disease. They found that carrying the gene added to the risk of developing serious memory problems, but not by a strong amount.
By adding up risk factors, the researchers were able to tabulate scores. Overall, those in the highest group of risk scores were seven times more likely to develop mild cognitive impairment than those in the lowest group.
“This risk scale may be an inexpensive and easy way for doctors to identify people who should undergo more advanced testing for memory issues or may be better candidates for clinical trials,” Dr. Petersen said.
The hope is that by identifying people at risk of Alzheimer’s at the earliest stages, they might be able to offer treatments at a stage when they may be most effective. Those found to be at possible risk might also be referred for brain scans and other tests that may be more accurate in diagnosing early dementia.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Alan B. Zonderman, PhD, Timo Grimmer, MD: “Risk of Mild Cognitive Impairment: The Olmsted County MCI Risk Score.” Neurology, Vol. 84, March 18, 2015.
V. Shane Pankratz, PhD, Rosebud O. Roberts, MBChB, Michelle M. Mielke, PhD, et al: “Predicting the Risk of Mild Cognitive Impairment in the Mayo Clinic Study of Aging.” Neurology, Vol. 84, March 18, 2015, pages 1-10.