Have you become more forgetful over the years? Rest assured that the minor memory lapses that occur with age are not usually signs of a serious neurological disorder, such as Alzheimer’s disease, but rather the result of normal changes in the structure and function of the brain. Want to keep your brain sharp? Keep learning and stay physically and mentally active, counsels Improving Memory, a Special Health Report from Harvard Medical School. Those strategies boost your "brain bank," improving the brain’s capacity to withstand damage associated with disease or injury.

Alzheimer’s disease doesn’t affect everyone in the same way. In people whose brains are being damaged by the disease, some continue to function normally while others suffer severe memory loss and other problems. Two components help explain the difference.

The first, called brain reserve capacity, is the number of nerve cells and nerve-to-nerve connections (synapses) in the brain. In theory, a person who has more brain “hardware” is able to maintain memory and thinking skills even when some of the hardware is damaged. The second element, cognitive reserve, reflects the brain's ability to develop and use alternative nerve pathways or thinking strategies when disease or injury damage parts of the brain. People whose brains have alternate networks or cognitive strategies are less likely to experience disruption in their mental processes.

Many things can reduce brain reserve capacity, including strokes, injury, and toxins, and there is little you can do to rebuild this genetically determined brain feature. But you can influence cognitive reserve. There is evidence that you can improve it—and lessen the risk of cognitive impairment—by being physically active and doing mind-engaging activities such as reading, writing, playing board or card games, participating in group discussions, and playing music.

The bottom line: Virtually any activity that stretches your brain can bolster your cognitive reserve. Engaging your brain with intellectually stimulating activities will afford your brain greater protection down the road.