Dog ownership and healthy brain aging: a pilot study

Dog ownership may benefit brain and cognitive health by supporting physical activity and social connectedness, among other mechanisms. Studies that include brain health outcomes (e.g., neuroimaging outcomes) are lacking. As the population ages, studies investigating whether and how dogs support healthy brain aging are needed, as dog ownership and dog walking are modifiable targets for dementia prevention efforts. This study piloted all methods for a full-scale investigation of how dog ownership in older adulthood impacts brain aging.

This was a cross-sectional study. Participants (n = 25; n = 13 dog owners) completed physical activity monitoring (activPAL + diary for 7 days) and questionnaires relating to social connectedness. They also completed cognitive testing (NIH Toolbox Cognition Battery) and brain magnetic resonance imaging (MRI). Brain structural volumes (e.g., total gray matter volume) and cortical thickness were quantified. Process outcomes of interest included sample characteristics and data completeness. Descriptive statistics were used to summarize the data overall and by group.

Participants were 74.8 ± 3.9 years old, 60% were female, 100% were non-Hispanic White, 84% had at least a 4-year college degree, and 76% reported very good or excellent health. Most (84%) provided complete survey, physical activity, cognition, and brain MRI data. Dog owners took 8,972 ± 5,650 mean steps per day, while non-dog owners took 7,107 ± 2,989 mean steps per day. Most dog owners (11/13; 85%) reported dog walking, and most (11/13; 85%) reported meeting people in their neighborhood through their dog. Dog owners scored 6.8 ± 2.9 on the PROMIS Social Isolation v2.0-Short Form 4a (scale 4-20, higher scores = more isolation), while non-dog owners scored 6.7 ± 2.7. Dog owners scored 112.2 ± 12.8 on the NIH Fluid Cognition Composite Score (100 indicates average function), while non-dog owners scored 116.3 ± 10.3. Total gray matter volume was 599,156 ± 10,035 mm³ for dog owners and 588,028 ± 12,945 mm3 for non-dog owners. Total cortical thickness was 2.35 ± 0.03 mm² (right hemisphere) and 2.35 ± 0.03 mm² (left hemisphere) for dog owners and 2.30 ± 0.04 mm² (right hemisphere) and 2.32 ± 0.04 mm² (left hemisphere) for non-dog owners.

This pilot research was performed to inform a larger study on the brain and cognitive health impact of dog ownership in older adulthood. This study confirmed feasibility of data collection procedures while identifying important modifications needed for the success and rigor of the hypothesis-testing study, namely that recruitment strategies must be modified in the larger study to ensure a more representative study sample with greater variability in mechanisms of interest (e.g., social connection, physical activity, dog walking).