Grant: Op Gr.: Mech. in Brain Aging/dementia-Caregiving/Care Prov. + Aging with Neurod.

There are currently 2 million Canadians living with attention-deficit/hyperactivity disorder (ADHD), making it the most common neurodevelopmental condition. Of these, most are adults aged 18-64 (1.17 million) or older adults aged 65+ (220,000). Despite how numerous they are, adults and seniors with ADHD remain critically understudied relative to younger cohorts. Given the aging of Canada's population, it is imperative to develop a better understanding of how these individuals will experience aging to optimize brain health into later life and ensure they are supported in aging well. This project will directly contribute to defining the determinants of healthy brain aging for this large group of neurodivergent Canadians, by clarifying the role of vascular health and stress in their experience of brain aging. We recently discovered that the cognitive abilities of older adults with ADHD are more severely impacted by cerebral small vessel disease (cSVD; diseases affecting the brain's blood supply) than similarly-aged adults without ADHD, suggesting that their brains are particularly vulnerable to the accumulation of vascular brain pathology during the aging process. The proposed project will determine whether this phenomenon depends on allostatic load. Allostatic load refers to the build-up of physical inflammation and cell damage as a consequence of exposure to chronic stress, which prevents the brain from warding off the development of diseases such as cSVD. There is a wealth of evidence that individuals with ADHD are exposed to decades of socioeconomic challenges, long-term emotional stress, and chronic social disadvantage, making it plausible that they experience significant allostatic load and consequently become vulnerable to the effects of cSVD and increase their risk for vascular dementia. Our results will provide new evidence about modifiable factors that may adversely impact the aging process in a novel, vulnerable comprising several million Canadians.