NPR's health reporters followed the emerging science on what keeps our brains and our minds healthy. Here are highlights of the studies that piqued our readers' interest the most.

Whether it's volunteering at a local school or taking soup to a sick neighbor, improving the welfare of others can also improve our own physical and mental health, a sizable body of research shows.

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Scientists scanned the brains of people who took psilocybin, including a member of the research team. The scans showed how the drug disrupts key networks, potentially enhancing brain plasticity.

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The brain appears to rely on synchronized waves to wash out waste products, including toxins associated with Alzheimer's disease.

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Chronic traumatic encephalopathy (CTE) goes far beyond the NFL. Everyday men and women worry they have the fatal disease, and they've turned to questionable brain products for help.

Without a cure for Alzheimer's and other forms of dementia, prevention is paramount. Habits that helped early humans thrive still make sense: a varied diet, exercise and an engaging social life.

Scientists have identified specialized brain cells that create two distinct kinds of thirst. Some cells respond to a need for water alone, while others produce a craving for water and salt.

(Image credit: Krisanapong Detraphiphat)

Whether it's exercise or housework, older Americans who move their bodies regularly may preserve more of their memory and thinking skills, even if they have brain lesions and other signs of dementia.

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Thirst is what compels us to start hydrating. Now scientists have found a brain circuit in mice that seems to switch off thirst when they've taken in enough fluid and before it gets dangerous.

(Image credit: Guido Mieth)