A study involving 100 healthy older adults (aged 60-80) has found that those with higher levels of physical activity showed more variable spontaneous brain activity in certain brain regions (including the precuneus, hippocampus, medial and lateral prefrontal, and temporal cortices). Moreover, this relationship was positively associated with better white-matter structure.

Higher rates of activity when the brain is “at rest” have previously been shown to be associated with better cognitive performance in older adults, especially in IQ and memory.

The brain regions showing this relationship all play an important role in major resting-state networks, including the default mode network, the motor network, and networks associated with executive control and salience detection. They are all highly connected.

Participants' physical activity over a week was measured using accelerometers. Cardiorespiratory fitness was also assessed. Participants were generally not very active and not very fit.

The findings add to evidence linking higher fitness and physical activity with greater brain integrity and higher cognitive performance. They are also consistent with previous studies showing an increase in such brain signal fluctuations among older adults participating in physical exercise programs.

Interestingly, level of brain activity fluctuations was only correlated with physical activity, not with cardiorespiratory fitness. This indicates that CRF and physical exercise cannot be considered as functional equivalents — there must be some aspects of physical activity not captured by a measure of cardiorespiratory fitness.

It's also worth noting that there wasn't a significant correlation between sedentary time and resting-state brain activity fluctuations, although this may be because the participants all showed not-very-dissimilar levels of sedentary time.

http://www.eurekalert.org/pub_releases/2015-08/uoia-slp082415.php

A six-month pilot study involving 101 healthy older adults (65+), who were randomly put into one of three exercise interventions or a no-change control, has found that the exercise groups all showed significant improvement in visual-spatial processing and attention, with more improvement in visual-spatial processing occurring in those with higher levels of exercise.

The benefits of increasing exercise for visual-spatial processing, however, were fully accounted for by improvements in cardiorespiratory fitness, suggesting that exercise intensity may be more important than exercise duration.

The researchers suggest that individualized exercise programs designed to maximize cardiorespiratory fitness will be of greatest benefit.

The three exercise levels were: 150 minutes per week (the recommended level); 75 minutes per week; 225 minutes per week. Exercise was supervised, and mainly consisted of treadmill walking of moderate intensity. Participants exercised 3-5 days a week. Performance in five cognitive domains were tested: Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning.

Note that only 77 individuals made it through the trial, and also adhered to at least 80% of the alloted amount of exercise. Unsurprisingly, the 225-minute group had the most trouble meeting the allotment: 70% of the group managed it, compared to 82% of the 75-minute group, and 85% of the 150-minute group. It's worth noting that, of those who met the 80% requirement, almost all (>95%) fully adhered to the prescription, and this was true across all exercise prescriptions.

http://www.eurekalert.org/pub_releases/2015-07/uokm-eci071515.php

A review and a large study have recently added to the growing evidence that type 2 diabetes is not only a risk factor for Alzheimer's, but is also linked to poorer cognitive function and faster age-related cognitive decline. The amount of this also seems to be related to glucose control in a dose-dependent manner.

Somewhat surprisingly, there is evidence that the association is not linked to vascular factors, but is in significant part explained by neuron loss. That part is not surprising — brains 'naturally' shrink with age, and growing evidence points to the importance of exercise (which promotes the growth of new neurons) in combating that loss. If diabetics are less likely to exercise (which seems likely, given the strong association with obesity), this may, at least in part, account for the greater brain atrophy.

Type 2 diabetes linked to poorer executive function

A meta-analysis of 60 studies involving a total of 9815 people with Type 2 diabetes and 69,254 control individuals, has found a small but reliable association between diabetes and poorer executive function. This was true across all aspects of executive function tested: verbal fluency, mental flexibility, inhibition, working memory, and attention.

Unfortunately, effective diabetes management does depend quite heavily on executive function, making this something of a negative feedback cycle.

http://www.eurekalert.org/pub_releases/2015-02/uow-t2d021315.php

Diabetes in midlife linked to greater age-related cognitive decline

A long-running U.S. study involving 13,351 adults, has found that cognitive decline over 19 years was 19% greater among those who had diabetes in midlife. Moreover, cognitive decline increased with higher hemoglobin A1c level and longer duration of diabetes.

At the beginning of the study, participants were aged 48-67 (median: 57), and 13% of participants were diagnosed as diabetic. Cognition was tested using delayed word recall, digit symbol substitution, and word fluency tests.

The findings support the view that glucose control in midlife is important to protect against cognitive decline later in life.

http://www.jwatch.org/na36497/2014/12/31/diabetes-midlife-associated-with-accelerated-cognitive

http://www.sciencedaily.com/releases/2014/12/141201191253.htm

http://www.psychiatryadvisor.com/diabetes-may-accelerate-cognitive-decline/article/386208/

Brain atrophy linked with cognitive decline in diabetes

A 2013 study showed that almost half of the cognitive impairment seen among diabetics was explained by their loss of gray matter.

Brain scans and cognitive tests of 350 people with Type 2 diabetes and 363 people without diabetes revealed that those with diabetes had more cerebral infarcts and greater shrinkage in specific regions of the brain. Diabetes was associated with poorer visuospatial memory, planning, visual memory, and processing speed. These associations were independent of vascular risk factors, cerebrovascular lesions, or white matter volume, but almost half of the associations were explained by the shrinkage of gray matter in the hippocampus and across the brain.

http://www.eurekalert.org/pub_releases/2013-09/mu-bal091113.php

There are five healthy behaviors that appear to significantly reduce the risk of dementia,

A 35-year study that monitored the healthy behaviors of 2,235 Welsh men aged 45 to 59 at the beginning of the study has found that those who consistently followed at least four of these five healthy behaviors — regular exercise, no smoking, acceptable BMI, high fruit and vegetable intake, and low/moderate alcohol intake — experienced a 60% reduction in dementia and cognitive decline compared with people who followed none. They also had 70% fewer instances of diabetes, heart disease, and stroke,.

Exercise was the most important of these factors.

Only 5% of the men were living a healthy lifestyle (i.e., following at least 4 of these healthy behaviors). Just under half of the 2235 men were non-smokers (46%), and around a third (35%) had an acceptable BMI. Only 15 men ate their “5+” daily (!!), so the requirement was reduced to only three or more portions of fruit and vegetables, enabling 18% to reach it. 39% exercised regularly and 59% reported alcohol intake within the guidelines. Only two men managed five healthy behaviors, and 109 managed four; 19% managed three; 36% two; 31% one; 8% couldn’t manage any.

http://www.futurity.org/five-healthy-behaviors-can-reduce-dementia-risk/

http://www.eurekalert.org/pub_releases/2013-12/cu-3ys120913.php