New studies show exercise can help fight Alzheimer's

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Good news for families with Alzheimer's patients.

Four new studies show exercise can help fight the disease.

One study shows even moderate walking can grow the area of the brain related to memory.

Meanwhile a new study finds the amount of sleep seniors get is directly related to their cognitive ability.

People who slept less than five hours or more than nine hours had lower mental ability than those who slept seven hours per day.

The researchers found that getting too little or too much sleep was cognitively equivalent to aging 2 years in people 70 years or older.

Copyright 2012 CBS 5 (Meredith Corporation). All rights reserved. CBS News contributed to this report.