Is Your Brain Shrinking

Most people's brains do shrink, or atrophy, with age. But the number of lost neurons is relatively small. It turns out that the decrease in brain volume and mass in normal aging results not so much from an actual loss of neurons but rather from changes within neurons: loss of neuronal branches (dendritic spines), decreased density of synapses, and deterioration of the myelin sheath that surrounds the axons of neurons.

Only in the presence of memory disorders, such as Alzheimer's disease, does the brain suffer dramatic destruction and loss of neurons. Loss of neurons in the hippocampus and eventually other areas of the brain directly contributes to the pronounced difficulty with short-term memory that's typical of people with Alzheimer's disease.

more highly activated region in the brains of the elderly high performers was being recruited to help out with the mental work of the memory task. This functional recruitment may be one of the compensatory tactics employed by the successfully aging brain.

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