Walking and Mediterranean diet may be the ticket to reducing dementia risk

By Dr. Chinta SidharthanOct 4 2023Reviewed by Susha Cheriyedath, M.Sc.

In a recent study published in the Journal of Alzheimer's Disease, researchers discussed the protocol and current progress of a study that investigates the effectiveness of regular walking and adherence to a Mediterranean-style diet in decreasing the risk of dementia and age-related cognitive decline in independently living older adults without existing cognitive impairments.

Study: A Mediterranean Diet and Walking Intervention to Reduce Cognitive Decline and Dementia Risk in Independently Living Older Australians: The MedWalk Randomized Controlled Trial Experimental Protocol, Including COVID-19 Related Modifications and Baseline Characteristics. Image Credit: Lightspring / Shutterstock

Background

A decline in cognitive functions such as spatial working and episodic memory is a natural function of age. However, a rapid decline in cognitive abilities often indicates a neuropathological deterioration that could lead to dementia. Lifestyle factors such as physical activity and diet are important modifiable risk factors for dementia. Furthermore, risk factors related to cardiovascular disease, such as arterial stiffness and high blood pressure, also contribute to an increased risk of dementia and cognitive decline. Targeting these risk factors through diet and exercise could lower the risk of dementia.

The Lancet Commission and World Health Organization's report on the prevention, interventions, and care associated with dementia has indicated the importance of physical activity and adherence to the Mediterranean diet to target the modifiable risk factors of dementia. Studies investigating the impact of the Mediterranean diet on health have reported improvements in cardiovascular risk measures, cognitive function, and memory among older individuals. Similar results have also been observed for physical activity interventions, but the evidence for both these interventions has primarily been from preclinical and prospective cohort studies.

About the study

In the present study, the researchers conducted a randomized controlled trial to determine the effectiveness of the MedWalk intervention, which promotes adherence to the Mediterranean diet and walking as a method of physical activity, implemented using proven psychosocial techniques such as motivational interviewing and cognitive-behavioral therapy (MI-CBT) to bring about behavioral change. The researchers hypothesized that the MedWalk intervention will result in a slower decline in cognitive function as compared to the control group, where participants will continue with their habitual lifestyles.

The study also aimed to examine the impact of the MedWalk intervention on factors such as quality of life, mood, arterial stiffness, cardiovascular health, and biomarkers such as inflammation, glucose regulation, nutrient status, and oxidative stress, which are linked to cognitive decline. Additionally, the study's secondary aims included evaluating the intervention's impact on factors such as health economy and cost-effectiveness.

This randomized controlled trial was conducted over two years among older adults living in retirement villages in Australia. These retirement villages provided a homogenous and consistent study set-up as compared to the broader community, which would be heterogeneous across various factors. These residential set-ups also encouraged mutual support conducive to fostering group walk sessions and adherence to dietary plans.

The MedWalk intervention was implemented over a year, with the first six months involving more frequent group walking and diet consultations, which became less frequent over the second half of the year. Primary and secondary outcomes were assessed after the baseline measurements occurred at six and 12 months. Due to the onset of the coronavirus disease 2019 (COVID-19) pandemic, the study had to be modified and significantly abbreviated. However, the researchers stated that while the duration of measurements of the primary and secondary outcomes had to be restricted due to the pandemic, the major hypotheses and aims of the study remained unchanged.

Progress

Despite the COVID-19 pandemic-associated reduction in the sample size and timeline of the study, the progress thus far indicated that baseline testing had been completed for 157 participants, who were being followed up for a year. The cognitive testing at baseline and during the half-yearly and yearly follow-ups is being conducted by blinded testers or researchers.

The MI-CBT approach is used to develop adherence to the Mediterranean-style diet, with a dietitian providing instructions, meal planning, and recipes to help improve adherence to the diet. Supervised group walking sessions with accredited exercise physiologists are provided to increase physical activity levels.

The Cambridge Neuropsychological Test Automated Battery's Paired Associated Learning task, which evaluates learning and visual memory, is being used to test the primary outcome of cognitive decline. Other tests included in the automated battery are being used for measuring secondary outcomes such as motor learning, spatial working memory, rapid visual information processing, and reaction time.

Questionnaires on anxiety, depression, stress, and general health are being used to assess mood, while the Pittsburgh Sleep Quality Index is being employed to evaluate sleep quality. Furthermore, arterial stiffness and central and peripheral blood pressures are also being recorded at baseline and during follow-ups, and various other indices are being used to assess the quality of life and the expanse of the participant's social network.

Conclusions

To summarize, the MedWalk intervention has been designed to examine the impact of a combination of a modified Mediterranean-style diet and increased physical activity in the form of group walks to lower cognitive decline rates among older adults. Due to the onset of the COVID-19 pandemic and associated social restrictions, the study is in progress with participants recruited from retirement village communities in Australia and a wider community.

If the results from this study are promising, the MedWalk intervention could potentially be applied to broader communities to decrease cognitive decline and the risk of dementia among older adults, which would also significantly reduce the health-related economic burden.