As the number of U.S. military veterans over the age of 55 continues to increase, helping them maintain their physical and mental health becomes more important. Unfortunately, about 10% of older veterans have been diagnosed with clinically significant levels of depression, which doubles the chances of also suffering from mental disorders including dementia. Finding lifestyle changes that will help counteract these effects becomes crucial to improve their quality of life.
One lifestyle change could be the addition of exercise, even in moderate amounts. A recent study, published in the American Journal of Geriatric Psychiatry, compared the cognitive health of veterans with and without depression alongside their reported level of physical activity and the presence of a variation to a genetic protein known to improve brain plasticity.
Using a web-based survey of 1,386 U.S. military veterans over the age of 50 (mean age = 63), the researchers collected data on four levels:
- The vets’ score on the Patient Health Questionnaire-2 which is used to screen for depression symptoms.
- The presence of a single-nucleotide polymorphism (SNP), the Val66Met allele, a mutation of the Brain-Derived Neurotrophic Factor (BDNF) protein. Without this SNP, BDNF helps build synaptic plasticity in the brain adding new neurons and aiding long-term memory. Val66Met jumbles the gene coding sequence, reducing BDNF production. This has been found to reduce hippocampal volume by 4-5% in older adults and contributes to worse cognitive performance. Vets were asked to submit saliva for genetic testing.
- Two tests of cognitive functioning:
- For a subjective survey of everyday cognitive struggles, the Medical Outcomes Study Cognitive Functioning Scale was used to measure changes in the past month in six domains; reasoning, concentration/thinking, confusion, memory, attention and psychomotor speed. A sample question asked of the vets was, “During the past month, how much of the time did you forget (i.e. things that happened recently, where you put things, appointments, etc.)”
- For an objective measure of cognitive function, the Cogstate Brief Battery was used to measure psychomotor speed, attention, visual learning, and working memory. The computerized tests are fast, easy to understand and well-validated especially for dementia and related diseases.
- A self-report question asking, “How many days per week do you typically engage in the following activities: sports/exercise.”
According to the researchers, the three goals of the data analysis were “1) To examine the direct effect of depression on cognitive functioning in a nationally representative sample of older U.S. military veterans; 2) to evaluate whether the BDNF Val66Met genotype and physical activity moderate the effect of depression on cognitive functioning; and 3) to determine whether there is an interaction between BDNF Val66Met genotype and physical activity in moderating the effect of depression on cognitive functioning in this population.”
Results showed positive relationships for all three areas. First, the data showed that vets with depression symptoms underperformed those without depression to a small to moderate degree on the cognitive functioning tests. On top of that, vets who carried the Val66Met allele showed lower cognitive functionality than those vets who did not carry the SNP, with and without depression.
Regular exercise helped across the board. Whether comparing those with depression or those with the Val66Met allele, exercisers outperformed non-exercisers in both the subjective and objective cognitive tests. Recommending an active lifestyle to older vets, as well as everyone over the age of 50, received even more support from this study.
“The finding that depressed nonexercisers had substantial reductions in cognitive function relative to depressed exercisers is particularly notable, as physical inactivity and depression are two leading modifiable risk factors for dementia that respectively account for 21% and 15% of the U.S. prevalence of Alzheimer’s disease and related dementias,” concluded the study authors.
