Exercise can enhance your cognitive and mental health, but not all types and intensities have the same effect on the brain. A recent Dartmouth study finds that the impacts of exercise are far more subtle, with certain intensity levels of exercise over time connected with distinct components of memory and mental health.
The findings, which were published in Scientific Reports, offer insight into how exercise may be improved. “Mental health and memory are fundamental to practically everything we do in our daily lives,” says Dartmouth assistant professor of psychology and brain sciences Jeremy Manning.
“Our research aims to provide the groundwork for understanding how varying levels of physical activity influence different areas of mental and cognitive health.”
The researchers invited 113 Fitbit users to complete a series of memory tests, answer some mental health questions, and disclose their exercise data from the previous year. They anticipated more active people to have better memory and mental health, but the results were more complicated. People who exercised at moderate intensities performed better on some memory tests, whereas those who exercised at high intensities fared better on others.
Participants who were more physically active reported greater levels of stress, whereas those who exercised at a lesser intensity on a regular basis reported lower levels of anxiety and despair.
Prior study has frequently focused on the effects of exercise on memory over a relatively short term, such as a few days or weeks, but Dartmouth researchers sought to investigate the impacts over a much longer timeframe. The data included daily step counts, average heart rates, the amount of time spent exercising in several FitBit “heart rate zones” (rest, out-of-range, fat burn, cardio, or peak), and other information gathered over a complete calendar year. The study’s participants were recruited online using Amazon’s Mechanical Turk, a crowdsourced workforce.
The study’s four types of memory tasks were designed to test different aspects of participants’ abilities over different timescales. Two sets of tasks were designed to assess “episodic” memory, which is used to recall autobiographical events such as what you did yesterday. Another set of exercises was created to assess “spatial” memory, which is useful to recall locations such as where you parked your car. The final series of activities examined “associative” memory, or the capacity to recall links between concepts or memories.
Participants who had been more active in the previous year had improved overall memory performance, but the precise areas of improvement relied on the sort of exercise they undertook.
The researchers discovered that people who exercised frequently at moderate intensities performed better on episodic memory tests, whereas participants who exercised frequently at high intensities performed better on spatial memory tasks. Sedentary individuals who rarely exercised performed worse on spatial memory tasks.
The researchers also discovered links between individuals’ mental health and memory ability. Participants who reported anxiety or depression performed better on spatial and associative memory tests, whereas those who claimed bipolar illness performed better on episodic memory tasks. Participants with higher levels of stress performed worse on the associative memory tests.
All of the team’s data and code are publicly available on Github to anybody who wants to examine or better understand the dataset.
“There’s a really nuanced relationship at play when it comes to physical exercise, memory, and mental health that cannot be summed in simple terms like ‘walking helps your memory’ or’stress affects your memory,'” says Manning. “Rather, various types of physical exercise and different characteristics of mental health appear to influence each part of memory differently.”
The team believes that with future investigation, their discoveries might have some fascinating applications. “For example,” Manning adds, “particular exercise regimes may be devised to help enhance students’ cognitive performance and mental health to help them prepare for a test or minimise their depressive symptoms.”