Out of shape? Your memory may suffer

Here’s another reason to drop that doughnut and hit the treadmill: A new study suggests aerobic fitness affects long-term memory.

Michigan State University researchers tested 75 college students during a two-day period and found those who were less fit had a harder time retaining information.

“The findings show that lower-fit individuals lose more memory across time,” said Kimberly Fenn, study co-author and assistant professor of psychology.

The study, which appears online in the research journal Cognitive, Affective & Behavioral Neuroscience, is one of the first to investigate young, supposedly healthy adults. Previous research on fitness and memory has focused largely on children, whose brains are still developing, and the elderly, whose memories are declining.

Participants studied related word pairs such as “camp” and “trail.” The next day, they were tested on the word pairs to evaluate long-term memory retention. Long-term memory is anything remembered more than about 30 seconds ago.

Aerobic fitness was gauged by oxygen consumption derived from a treadmill test and factored with the participants’ weight, percent body fat, age and sex.

The findings speak to the increasingly sedentary lifestyles found in the United States and other Western cultures. A surprising number of the college students in the study were significantly out of shape and did much worse at retaining information than those who were extremely fit, Fenn said.

Her co-authors included kinesiology researchers Matthew Pontifex and Karin Pfeiffer.

Regular aerobic exercise boosts memory area of brain in older women

Regular aerobic exercise seems to boost the size of the area of the brain (hippocampus) involved in verbal memory and learning among women whose intellectual capacity has been affected by age, indicates a small study published online in the British Journal of Sports Medicine.

The hippocampus has become a focus of interest in dementia research because it is the area of the brain involved in verbal memory and learning, but it is very sensitive to the effects of ageing and neurological damage.

The researchers tested the impact of different types of exercise on the hippocampal volume of 86 women who said they had mild memory problems, known as mild cognitive impairment - and a common risk factor for dementia.

All the women were aged between 70 and 80 years old and were living independently at home.

Roughly equal numbers of them were assigned to either twice weekly hour long sessions of aerobic training (brisk walking); or resistance training, such as lunges, squats, and weights; or balance and muscle toning exercises, for a period of six months.

The size of their hippocampus was assessed at the start and the end of the six month period by means of an MRI scan, and their verbal memory and learning capacity was assessed before and afterward using a validated test (RAVLT).

Only 29 of the women had before and after MRI scans, but the results showed that the total volume of the hippocampus in the group who had completed the full six months of aerobic training was significantly larger than that of those who had lasted the course doing balance and muscle toning exercises.

No such difference in hippocampal volume was seen in those doing resistance training compared with the balance and muscle toning group.

However, despite an earlier finding in the same sample of women that aerobic exercise improved verbal memory, there was some evidence to suggest that an increase in hippocampal volume was associated with poorer verbal memory.

This suggests that the relationship between brain volume and cognitive performance is complex, and requires further research, say the authors.

But at the very least, aerobic exercise seems to be able to slow the shrinkage of the hippocampus and maintain the volume in a group of women who are at risk of developing dementia, they say.

And they recommend regular aerobic exercise to stave off mild cognitive decline, which is especially important, given the mounting evidence showing that regular exercise is good for cognitive function and overall brain health, and the rising toll of dementia.

Worldwide, one new case of dementia is diagnosed every four seconds, with the number of those afflicted set to rise to more than 115 million by 2050, they point out.

Aerobic exercise boosts brain power in elderly

Evidence for the importance of physical activity in keeping and potentially improving cognitive function throughout life was found in a literature review in Psychonomic Bulletin & Review by Hayley Guiney and Liana Machado from the University of Otago, New Zealand.

• Cognitive functions such as task switching, selective attention, and working memory appear to benefit from aerobic exercise. Studies in older adults reviewed by the authors consistently found that fitter individuals scored better in mental tests than their unfit peers.
  
  
• Scores in mental tests improved in participants who were assigned to an aerobic exercise regimen compared to those assigned to stretch and tone classes.
  
  
• Exercise has been found to positively affect mental tasks relating to activities such as driving, an activity where age is often seen as a limiting factor.
  
  
• MRI studies of aging have shown that, as compared with unfit, highly fit older adults exhibit less age-related atrophy in the prefrontal and temporal cortices; preserved neural tracts connecting the prefrontal cortex to other regions of the brain; superior white matter integrity in the corpus callosum; greater gray matter density in the frontal, temporal, and parietal cortices; and greater hippocampal volumes.
  
  
• Physically active older adults have both higher circulating neurotrophin levels and gray matter volumes in the prefrontal and cingulate cortex.
  
  
• These results were not replicated in children or young adults, except for memory tasks. Both the updating of working memory and the volume of information which could be held was also better in young fitter individuals or those put on an aerobic exercise regime. “Although the evidence to date supports a wider range of executive functions benefiting from regular exercise in older adults, the relative lack of supportive evidence in young adults and children may, in part, reflect a poverty of studies, especially controlled trials, in these age groups,” the authors suggest.