You can think of cognitive reserve as your brain's ability to improvise and find alternate ways of getting a job done. It reflects how agile your brain is in pulling in skills and capacities to solve problems and cope with challenges. Cognitive reserve is developed by a lifetime of education and curiosity.

The concept of cognitive reserve originated in the late 1980s, when researchers described individuals with no apparent symptoms of dementia who were nonetheless found at autopsy to have brain changes consistent with advanced Alzheimer's disease. These individuals did not show symptoms of the disease while they were alive because they had a large enough cognitive reserve to offset the damage and continue to function as usual.

Since then, research has shown that people with greater cognitive reserve are better able to stave off symptoms of degenerative brain changes associated with dementia or other brain diseases, such as Parkinson's disease, multiple sclerosis, or a stroke. A more robust cognitive reserve can also help you function better for longer if you're exposed to unexpected life events, such as stress, surgery, or toxins in the environment. Such circumstances demand extra effort from your brain—similar to requiring a car to engage another gear.

The heart of our brain health and cognitive fitness program, however, involves lifestyle changes. Researchers at Harvard Medical School have identified six cornerstones to any effective brain health and cognitive fitness program.

Step 1: Eat a plant-based diet

Step 2: Exercise regularly

Step 3: Get enough sleep

Step 4: Manage your stress

Step 5: Nurture social contacts

Step 6: Continue to challenge your brain

These factors are equal parts of a cohesive plan—they don't work in isolation. Simply eating more fiber or adding a morning walk to your routine isn't enough to forestall mental decline. Instead, exercise, diet, sleep, stress management, social interaction, and mental stimulation work in concert to yield results.