How Your Brain Ages

"I can no longer read," one fifty-five-year-old woman told me. "By the time I get to the end of a page, I've completely forgotten what I read a moment before. I end up rereading the same passage two or three times."

"Last week I rented a video," said a fifty-one-year-old man. "As I watched the movie, it seemed vaguely familiar. Finally, it began to dawn on me that I'd seen the movie before. It turns out I'd rented it just two weeks earlier!"

Can you tell which of these people has a brain disorder? The answer is, neither one. Both were reporting difficulties with attention, learning, and recall that are typical for people in middle age and older. Starting around age fifty, most people experience the following brain changes that directly affect memory and other cognitive functions:

• There is a decrease in the number of synapses, or "meeting points" between neurons.

• The number and functionality of receptors (the docking points on neurons where chemical messages are received) are diminished.

• Certain neurotransmitters (the chemical substances that regulate cell-to-cell communication) become less available to the brain for a variety of reasons. A3.

• White matter pathways (the bundles of neuronal fibers that transmit messages throughout the central nervous system) develop lesions, or abnormalities, that can impair their functioning.

All of these changes slow down or interrupt the communication between neurons. I'll tell you more about these communication problems a little later in this chapter.

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