Exercise

Moderate intensity exercise can benefit memory performance

Three experiments involving a total of 59 people provides more evidence that moderate intensity exercise (e.g., brisk walking, water aerobics, cycling) is enough for cognitive improvement. Indeed, moderate intensity exercise had the most beneficial effect on memory performance.

Data from a publicly available database of 1206 MRI brain scans from the Human Connectome Project has revealed that physical fitness is associated with better brain structure and brain functioning in young adults.

The volunteers (average age 29) had their physical fitness assessed using a "two-minute walking test", where each person is asked to walk as fast as possible for 2 minutes and the distance is then measured. Cognition was assessed using a series of cognitive tests to create a global cognition score.

A study in which 64 sedentary older adults (aged 60-88) participated in a 12-week exercise program found that those who engaged in high-intensity interval training (HIIT) saw an improvement of up to 30% in memory performance while participants who engaged in moderate-intensity aerobic exercise saw no improvement, on average.

Moreover, improvements in fitness levels directly correlated with improvement in memory performance.

Participants participated in three sessions per week. A control group engaged in stretching only.

A small study involving 12 very fit older adults (aged 50-80; average age 61) found that, after stopping their exercise routines for 10 days, there was a significant decrease in blood flow to several brain regions, including the hippocampus and regions involved in the default mode network (both the hippocampus and the DMN show deterioration early in Alzheimer’s).

A study involving 30 previously physically inactive older adults (aged 61-88) found that a three-month exercise program reversed some brain atrophy.

Participants included 14 with MCI. The exercise program included moderate intensity walking on a treadmill four times a week over a twelve-week period. On average, cardiorespiratory fitness improved by about 8% as a result of the training in both the healthy and MCI participants. Fitness was assessed using peak oxygen capacity rates.

A long-running study following 387 Australian women found that regular exercise in middle age was the best lifestyle change they could make to prevent cognitive decline in their later years.

The women were aged 45-55 when the study began in 1992. Health and lifestyle factors were assessed at intervals over the next 20 years.

Memory was assessed using a Verbal Episodic Memory test in which they were asked to learn a list of 10 unrelated words and attempt to recall them 30 minutes later.

Memories are made through a synaptic-strengthening process called long-term potentiation (LTP). Prolonged stress weakens the synapses, which decreases LTP, thus having a negative effect on memory. A mouse study found that when exercise co-occurs with stress, LTP levels are not decreased, but remain normal. The exercising but stressed mice also performed as well on the memory tests as the non-stressed mice, and better than both groups of sedentary mice.

Running is mentioned specifically because the exercise the mice took involved running wheels.

A Canadian study involving 45,522 adults (30+) found that higher levels of physical activity, eating more fruits and vegetables, and having a BMI in the normal weight or overweight range were each associated with better cognitive function in both younger and older adults.

Specifically, for those who were normal weight or overweight (but not obese), eating more than 10 servings of fruit and vegetable daily was linked to better cognitive functioning. When moderate exercise was added, those eating less than five servings, reported better cognitive functioning.

A rat study comparing different forms of exercise has found that running was much more effective than HIIT or resistence training in generating new brain cells.

Most exercise studies involving rats have used running wheels, and the benefits of these for the creation of new neurons in the hippocampus (adult neurogenesis) have been well-demonstrated. This study used two other (rather ingenuous) strategies to mimic high-intensity interval training and weights training.