Self-rated physical fitness, physical activity, and memory in old age — two new studies

18 November, 2014 in subject Okategoriserade

One new study links self-rated physical fitness at midlife with risk of dementia in old age. Another finds that self-reported physical activity can offset the negative influence of certain gene variants on memory of past events.
“How is your current physical fitness: very good, good, satisfactory, relatively poor, or very poor?”
A recent study suggests that this question, asked during midlife, might help identify those with a higher risk of developing dementia later on. The study, performed by an international team of researchers that included scientists from ARC, examined whether self-rated fitness at midlife and declining fitness over time were related to dementia in later life.
Researchers used data from the Cardiovascular risk factors, ageing and incidence of dementia (CAIDE) study. CADE participants were a random sample of more than 1400 older people in Finland who had taken part in studies of cardiovascular disease when they were middle-aged. As part of these earlier studies, they rated their physical fitness.
CAIDE researchers re-examined the participants in 1998 and again between 2005 and 2008, asking about perceived physical fitness and checking for dementia. In the group as a whole, poor midlife fitness was related to a higher risk for dementia than good midlife fitness, even after taking several factors into account, including physical activity, BMI, and chronic diseases. Those whose self-rated fitness declined after midlife had a higher risk of dementia than those with unchanged fitness. Risks associated with declining fitness were particularly high in participants who carried the ε4 variant of the APOE gene.
The researchers believe the connection between perceived physical fitness and risk of dementia is complex and involves multiple lifestyle and biological factors, such as a less active lifestyle, poor diet, limited social ties, poor health, inflammation, and genetic factors.
“Although it relates to physical activity, self-rated physical fitness is a broader measure of many factors. It may help to flag potential problems, because one simple question can capture many different and relevant risk factors for dementia. However, it cannot pinpoint why the risk of dementia is increased. For that we still need to study more specific measures of biological and lifestyle factors behind physical fitness,” says Alina Solomon, one of the authors of the study.
Another study at ARC looked at the benefits of staying active in old age. Researchers at ARC and the Karolinska University Hospital set out to test whether specific combinations of variants of three genes—PICALM, BIN1, and CLU—were associated with poorer memory for past events in older adults. They also wanted to learn whether physical activity in old age could counteract any effects of these genes.
To find out, researchers used information on more than 2400 people aged 60 and older who had taken part in the Swedish National study on Aging and Care. First, the research team created a genetic risk score based on the three genes. Next, they compared the risk scores with the results of cognitive tests, such as tests of memory and general knowledge. Even after removing the effects of the APOE gene from the mix, a higher genetic risk score was related to poorer memory for past events. It was not related to deficits in any other abilities, which means these genes specifically influence memory.
The researchers also looked at the relationship between the risk score, cognitive test results, and how often participants said they engaged in either light or moderate/intense physical activity over the past year. Light activities included walks in the park or woods, short bike rides, and golf. Moderate/intense activities were things like jogging, fast walks, heavy gardening, long bike rides, and cross-country skiing.
“The good news is that even light exercise like walking at normal speed several times a week was enough to counteract the negative influence of the genes on memory. Physical activity is beneficial in general, but the message of this study is that it seems especially beneficial for people at higher genetic risk for poor memory,” says lead author Beata Ferencz.
Read more:
Kulmala J, Solomon A, Kåreholt I, Ngandu T, Rantanen T, Laatikainen T, et al. Association between mid- to late life physical fitness and dementia: evidence from the CAIDE study. J Intern Med [In press:online] 2014. Available from: DOI: 10.1111/joim.12202.
Ferencz B, Laukka EJ, Welmer AK, Kalpouzos G, Angleman S, Keller L, et al. (2014). The benefits of staying active in old age: Physical activity counteracts the negative influence of PICALM, BIN1 and CLU risk alleles on episodic memory functioning. Psychol Aging. Jun;29(2):440-9.doi: 10.1037/a0035465.