Your brain is a thinking organ that learns and grows by
interacting with the world through perception and action. Mental
stimulation improves brain function and actually protects
against cognitive decline, as does physical exercise. The human
brain is able to continually adapt and rewire itself. Even in
old age, it can grow new neurons. Severe mental decline is
usually caused by disease, whereas most age-related losses in
memory or motor skills simply result from inactivity and a lack
of mental exercise and stimulation. Source: Franklin Insititute