Exercise

A large study, involving nearly 14,000 older adults (50+) participating in the 2006 Health and Retirement Study, found that weaker handgrip strength was associated with a greater risk of developing cognitive impairment, especially severe impairment, over the eight-year study period.

Moreover, there was a dose-response type relationship, with every 5-kilogram (11-pound) reduction in handgrip strength being associated with a 10% greater risk of cognitive impairment and an 18% greater risk of severe cognitive impairment.

A study of 105 female college students found that those with the highest levels of stored iron had the highest grades. Fitness was also a factor, but while the effect of fitness was greater overall than the impact of iron status, both factors together had an even greater effect. The difference between fit women with normal iron levels and unfit women who were iron deficient was sufficiently large to to drop or increase a letter grade.

The association between the measure of fitness (peak oxygen intake) and grade was mediated by working memory.

A small UK study involving 28 healthy older adults (20 women with average age 70; 8 men with average age 67), has found that those with higher levels of aerobic fitness experienced fewer language failures such as 'tip-of-the-tongue' states.

The association between the frequency of tip-of-the-tongue occurrences (TOTs) and aerobic fitness levels existed even when age and vocabulary size was accounted for. Education level didn't affect TOTs, but only a few of the participants hadn't gone to university, so the study wasn't really in a position to test this out.

An Australian study involving 102 older adults (60-90) has concluded that physical fitness and arterial stiffness account for a great deal of age-related memory decline.

A long-running study involving 454 older adults who were given physical exams and cognitive tests every year for 20 years has found that those who moved more than average maintained more of their cognitive skills than people who were less active than average, even if they have brain lesions or biomarkers linked to dementia.

Data from the English Longitudinal Study of Aging, in which nearly 4,000 older adults (60+) had their walking speed assessed on two occasions in 2002-2003 and in 2004-2005, those with a slower walking speed were more likely to develop dementia in the next 10 years. Those who experienced a faster decline in walking speed over the two-year period were also more likely to develop dementia.

https://www.eurekalert.org/pub_releases/2018-03/ags-oaw032318.php

Exercise activates brain networks in older adults

A study involving healthy older adults (55-85) found that recall was better after a session of moderately intense exercise, and several crucial brain regions showed greater activation.

The recall task involved identifying famous names and non famous ones. The test occurred 30 minutes after the exercise session (using an exercise bike) and on a separate day after a period of rest.

A small pilot study, in which participants had brain scans and working memory tests before and after single sessions of light and moderate intensity exercise and after a 12-week long training program, has shown that immediate cognitive effects from exercise mirror long-term ones. Participants who saw the biggest improvements in cognition and functional brain connectivity after single sessions of moderate-intensity physical activity also showed the biggest long-term gains in cognition and connectivity.

How exercise may protect against Alzheimer's

Previous research uncovered a hormone called irisin that is released into the circulation during physical activity, and appeared to play a role in energy metabolism. Mice studies have now found that irisin protected memory and synapses in the brain — disabling irisin in the hippocampus resulted in synapses and memory weakening; boosting brain levels of irisin improved synapses and memory.

Data from 196,383 older adults (60+; mean age 64) in the UK Biobank found that a healthy lifestyle was associated with lower dementia risk regardless of genes.

Both an unhealthy lifestyle and high genetic risk were associated with higher dementia risk.