Life purpose linked to 28% lower risk of cognitive decline

An analysis of the Health and Retirement Study data found that individuals who had a stronger sense of purpose in life at the start of the study were less likely to develop cognitive impairment during the follow-up period, which was up to 15 years. The paper was published in the American Journal of Geriatric Psychiatry.

As people age, they may experience a gradual decline in mental abilities such as memory, attention, and processing speed. This decline is a natural part of aging, but the pace and extent of this change vary greatly among individuals. Studies have identified many factors that may accelerate cognitive decline, including stress, sedentary behavior, poor diet, and limited social engagement.

This issue is becoming more important today because people are living longer than ever before. As life expectancy rises, the proportion of older adults in the population grows, leading to more people experiencing age-related cognitive changes. Consequently, the topic of preventing or delaying cognitive decline is attracting significant interest from researchers.

Study authors Nicholas C. Howard and his colleagues wanted to explore the association between purpose in life and the risk of developing mild cognitive impairment or dementia. Purpose in life is defined as a person’s tendency to derive meaning from and make sense of life experiences.

Previous studies have already reported that purpose in life is associated with a lower risk of Alzheimer’s disease (a type of dementia) and mild cognitive impairment. However, most of those studies focused on individuals aged 70 years or older or were conducted on smaller groups of participants. The authors of this new study wanted to verify this finding in a large, diverse, US population-based cohort.

They analyzed data from the Health and Retirement Study, focusing on individuals assessed between 2006 and 2020. The Health and Retirement Study is sponsored by the National Institute on Aging and is conducted by the University of Michigan.

These researchers analyzed data from 13,765 individuals who were at least 45 years old and had normal cognitive performance at the start of the study. They used data on participants’ purpose in life taken at baseline, whether they developed cognitive impairment during the follow-up period, APOE genotyping, and various other demographic and psychological characteristics.

APOE genotyping is a genetic test that identifies which version of the apolipoprotein E (APOE) gene a person carries. This was used to assess the risk of Alzheimer’s disease, as it is known that having the APOE E4 variant of this gene is associated with an increased risk, particularly if a person inherits this variant from both parents (i.e., if they are homozygous for this gene variant).

Results showed that 13% of participants developed cognitive impairment during the follow-up period, which lasted up to 15 years (the median was 8 years). Participants with a stronger purpose in life at the start of the study were less likely to develop cognitive impairment compared to their peers with a weaker purpose in life.

After taking into account sex, baseline age, depression, education level, and race/ethnicity, participants with the strongest sense of purpose in life still had an approximately 28% lower risk. The association remained significant even after accounting for whether participants carried the APOE E4 gene variant.

“Higher PiL [purpose in life] was associated with approximately 28% lower risk for developing cognitive impairment and a later onset of cognitive impairment across the studied ethnic/racial groups, even among those with genetic risk for dementia. These findings indicate that fostering a sense of life purpose has the potential to reduce cognitive impairment and dementia risk,” the study authors concluded.

The study contributes to the scientific understanding of factors affecting cognitive decline. However, it should be noted that the design of this study does not allow for definitive causal inferences. While it is possible that a stronger purpose in life protects against cognitive decline, it is also possible that early, undetected brain changes lead to a reduced sense of purpose (reverse causality), or that another unmeasured factor leads to both a stronger purpose in life and protection against cognitive decline.

The paper “Life Purpose Lowers Risk for Cognitive Impairment in a United States Population-Based Cohort” was authored by Nicholas C. Howard, Ekaterina S. Gerasimov, Thomas S. Wingo, and Aliza P. Wingo.