New thesis on mental stimulation to prevent Alzheimer's disease

Previous studies have shown that mental stimulation from education and occupational activities is associated with better cognitive function among older adults. These sources of mental stimulation also seem to affect the clinical expression of common Alzheimer's Disease (AD) biomarkers of neuropathology in conjunction with the rate of cognitive decline. The main focus of my thesis was to investigate if the complexity of an individual’s occupation (demands from intellectual and social activities at work) was associated with the intervention effect on the cognitive outcomes of a randomized controlled trial (RCT) involving a lifestyle intervention (diet, exercise, cognitive training, cardiovascular risk monitoring and social stimulation). The thesis also investigated if factors relating to mental stimulation, such as education (schooling) and occupational complexity is associated with better cognitive performance in older adults at-risk for dementia and if it can provide resilience against the cognitive effects of Alzheimer's Disease (AD) neuropathology. 

Which are the most important results? 

That occupational complexity did not affect the cognitive outcomes of a lifestyle RCT intervention except for the executive function outcome. Where higher levels of intellectual demands of an individual’s occupation was associated with a greater intervention effect in the executive function domain after a two-years lifestyle intervention. Higher levels of occupational complexity also do seem to be associated better cognitive performance among individuals at-risk for dementia (based on a cardiovascular risk score) but does not seem to provide strong resilience against AD neuropathology. Among individuals with prodromal AD (early symptomatic stage of Alzheimer's Disease) occupational complexity does seem to provide resilience against one common type of neuropathology that causes AD, which is the tau protein. This was also found for education level, but the association was dependent on age (decreasing with age).

How can this new knowledge contribute to the improvement of people’s health?

It can advance the field of AD research by moving from only investigating average treatment effects of interventions (non-pharmacological and pharmacological) to also investigating individualized treatment effects. This could lead to better outcomes of treatments and save healthcare resources and spending, ultimately moving towards precision medicine which is treatments tailored to each individual. The knowledge generated in this thesis can also help to design better RCTs and thus create better evidence-based medicine.

What’s in the future for you? Will you continue to conduct research?  

Yes, after my dissertation I will start a postdoctoral position at Stanford University where I will be working on projects that investigates how and if spending time in nature and green spaces can affect mental and physical health. Partly by conducting a RCT that looks at how parks in cities can improve different health outcomes.

Engaging in a healthy lifestyle and making the right changes can be challenging in the long-term but by incorporating more nature in the equation I think we can increase our chances of being successful at making peoples life’s healthier and hopefully also making people more aware of the value of nature and green areas.