Improving Cognition Through Exercise – Part 2

Improving Cognition Through Exercise - Part 2

Contributed by Julia C. Basso, Post-doctoral Research Associate, New York University, Center for Neural Science

Improving Cognition Through Exercise – Part 2

During the aging process, a variety of changes occurs within the brain. These changes include decreases in neurogenesis or new neuron growth, detriments in the vasculature surrounding the brain tissue, and deterioration in the glia or support cells of the brain. Consequently, they cause a variety of functional changes for the aging individual. Cognitive decline is a frequent occurrence as we age. Some individuals progress to Mild Cognitive Impairment (MCI) or dementia disorders, such as Alzheimer’s disease (AD).

In fact, more than 16 million people in the United States are living with cognitive impairment. Roughly 5.1 million of these individuals diagnosed with AD. Cognitive decline, however, is not an inevitable result of aging. Fortunately, a healthy lifestyle is one way to ward off age-related memory issues. Recent scientific evidence indicates that exercising throughout life helps to prevent a decline in cognitive function. Furthermore, exercise may even help ameliorate symptoms in patients with dementia. 

Improving Cognition Through Exercise - Part 2Function Follows Fitness

A collection of work shows that in elderly individuals, higher levels of fitness predict higher levels of cognitive functioning (Prakash et al., 2015). Additionally, research that has examined the progression of cognition over the course of aging shows that higher levels of physical fitness delay or prevent age-related cognitive decline. A meta-analysis of this work that examined 15 studies, including 33,816 non-demented subjects followed over 1-12 years, determined that healthy individuals who report high levels of physical activity show a 38% reduction in the risk of cognitive decline (Sofi et al., 2011). Though these types of studies are informative, they are hampered by the fact that they often rely on self-reported physical activity measures. Or, they examine simple correlations of physical fitness and cognition. In order to answer the question of whether exercise enhances cognitive function, interventional studies are needed.

Cognitive Abilities and Exercise

One recent interventional study examined the effect of various types of exercise on a variety of cognitive abilities in healthy elderly individuals (Iuliano et al., 2015). Eighty previously sedentary participants, aged 55 years and older (66.96±11.73 years), were randomly assigned to one of three exercise groups. These groups trained for 12 weeks or a control group that performed no exercise.

The three types of exercise groups included: a resistance group that performed high-intensity strength training of six muscles groups including the shoulders, arms, chest, abdomen, back and legs; a cardiovascular group that performed high-intensity cardiovascular training on either the treadmill, stationary bicycle, or step machine; and a postural group that performed low-intensity training using postural and balance exercises. Consequently, before and after the 12-week training period, participants underwent a series of neuropsychological tasks that assess cognitive functions that are known to deteriorate with age.

This battery of tasks, which included the Attentive Matrices Test, the Raven’s Progressive Matrices Test, the Stroop Color Word Interference test, the Trail Making Test, and the Drawing Copy Test, assessed attention, abstract reasoning, inhibitory control, processing speed and mental flexibility, and motor planning respectively. They found that different types of training are beneficial to different aspects of cognitive function. Resistance training enhanced motor planning whereas cardiovascular training enhanced attention and abstract reasoning. Low-intensity postural training did not enhance any of the cognitive abilities examined.

Long-Term Exercise and MCI

Other work has examined the effects of long-term exercise in patients with MCI, which is a syndrome characterized by problems in memory and thinking. Approximately 10-20% of the United States population aged 65 years and older has been diagnosed with MCI. Furthermore, these individuals have a higher likelihood of progressing to AD and other dementias. Suzuki et al. (2013) conducted a longitudinal study to see whether a six-month long multi-component exercise regimen could improve cognition in MCI patients. Hence, 100 elderly individuals, 65 years and older (75.4±7.1 years), living with MCI were randomly assigned to either an exercise group or an educational control group.

The exercise group participated in a 90-minute exercise program, twice per week. This program included aerobic exercise, strength training, balance training, and dual-task training. In this training, researchers asked participants to perform cognitive tasks (like creating a poem) while exercising. The control group attended two health-related education classes during the course of the 6 months. In order to assess cognitive function before and after the 6-month period, the study required all participants to complete the Mini-Mental State Examination (MMSE). They also completed the cognitive subscale of the Alzheimer’s Disease Assessment Scale. Finally they had to remember a short story. Initially, the analyses revealed no significant differences between the two groups in the change in cognition over time.

Interestingly, the analyses were restricted to subjects who had amnestic MCI. This is a subtype of MCI characterized specifically by memory loss rather than impairments in thinking, planning, organization or judgement. The researchers found that compared to the control group who showed detriments in in cognitive functioning over the 6 months, exercisers significantly improved in general cognitive ability as assessed by the MMSE and short-term memory as assessed by story recall.

Learning and Memory

This collection of work shows that the types of cognitive processes most sensitive to physical activity depend on two brain regions involved in learning and memory: the prefrontal cortex and the hippocampus. The prefrontal cortex supports executive functioning This includes attention, short-term or working memory, processing speed, decision-making, and the ability to switch between tasks or cognitive flexibility. The hippocampus, on the other hand, affects long-term memory. This is the ability to distinguish between stimuli or pattern separation, and spatial navigation, or the ability to know where we are in space and navigate through our environment. A myriad of regions make up the brain. All of these regions support many different types of learning and memory. Also, a distinct possibility exists that exercise improves other aspects of cognition besides those that depend on the prefrontal cortex and hippocampus.

Work in rodents shows exercise-induced brain changes in areas such as the motor cortex, cerebellum, striatum, and amygdala, to name a few. Therefore, many questions remain regarding the effects of exercise on aspects of learning and memory dependent on other brain structures besides the prefrontal cortex and hippocampus.

Decreasing the Risk for Cognitive Decline

In conclusion, exercise helps to decrease the risk for cognitive decline. It also helps slow the progression of memory loss in patients with MCI. Practically, this work suggests that we can maximize the cognitive benefits we receive from exercising at high, rather than low, intensities. These benefits maximize further by combining strength training with cardiovascular training. Additionally, exercise appears to be helpful in promoting cognitive function whether you are healthy or already suffer from cognitive decline. So, go get exercising – it will help you function better physically as well as mentally!

References:

Iuliano, E., di Cagno, A., Aquino, G., Fiorilli, G., Mignogna, P., Calcagno, G., & Di Costanzo, A. (2015). Effects of different types of physical activity on the cognitive functions and attention in older people: A randomized controlled study. Experimental gerontology70, 105-110.

Prakash, R. S., Voss, M. W., Erickson, K. I., & Kramer, A. F. (2015). Physical activity and cognitive vitality. Annual review of psychology66, 769-797.

Sofi, F., Valecchi, D., Bacci, D., Abbate, R., Gensini, G. F., Casini, A., & Macchi, C. (2011). Physical activity and risk of cognitive decline: a meta‐analysis of prospective studies. Journal of internal medicine269(1), 107-117.

Suzuki, T., Shimada, H., Makizako, H., Doi, T., Yoshida, D., Ito, K., … & Kato, T. (2013). A randomized controlled trial of multicomponent exercise in older adults with mild cognitive impairment. PloS one8(4), e61483.You Might Like:

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