ADHD often disappears before adulthood. In the US, it affects 8–12% of children and teenagers and 4.4% of adults.
Brain health refers to the absence of neurological disease and maintenance of optimal cognitive function. A healthy and nutrient-dense diet supports brain health. While some supplements may help with cognition, maintaining adequate nutritional status is essential for preserving brain health.
The brain is the body's command center, controlling functions like movement and cognition, which includes problem-solving, memory, and information processing. Maintaining brain health usually involves preventing the development of neurologic conditions like Alzheimer’s disease, epilepsy, brain injury, and Parkinson’s disease. The World Health Organization (WHO) defines brain health as “a state in which every individual can realize their own abilities and optimize their cognitive, emotional, psychological, and behavioral functioning to cope with life situations.” 
Following a balanced and nutrient-dense diet has a positive effect on brain health and function. The Mediterranean Diet, Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets are associated with reduced cognitive decline and reduced risk for developing Alzheimer’s disease. Foods like lean meats, fruits and vegetables, whole grains, nuts, seeds, and fish have positive effects on brain health. In contrast, diets rich in saturated fat, sugar, and processed food can impair brain health.
Common supplement ingredients for improving cognition include alpha GPC, Bacopa monnieri, blueberry, caffeine, Ginkgo biloba, ginseng, Huperzine A, oxiracetam, and theanine.
Optimal nutrient intake is also important for maintaining brain health, particularly iodine, zinc, copper, vitamin B1, vitamin B3, vitamin B12, and folic acid. Supplementation with these nutrients may be advised if dietary intake is inadequate.