Everyday Q&A: How does aging affect memory?

Whether they are misplacing their keys or forgetting a cousin’s name, many lament the fact that they are just not as sharp as they once were. The gradual deterioration of memory begins as early as our twenties and picks up speed when we reach our fifties.

In general, older people have more difficulty learning new things, retrieving old information, and multitasking. In order to understand what causes this weakening, we must first understand how memory works.

When the senses perceive something, several parts of the brain, including the hippocampus and frontal cortex, determine whether it will be encoded as a memory. Based on numerous factors, including how interested we are in the subject, how closely we are paying attention, and whether we are consciously trying to remember, electrical impulses then carry the information to be stored in various sections of the brain.

These impulses carry the information across the synapses between neurons via the release of chemical messengers called neurotransmitters. If more cells send messages to one another, then the connections between the synapses become stronger.

Thus, repetition of an action – such as going over information multiple times while studying for a test – can strengthen these connections and improve the brain’s ability to remember. Later, this information can then be retrieved from storage.

As we age, the brain loses cells that are essential in the encoding and retrieval processes of memory. Overall brain weight decreases, and among the cells lost are those that produce neurotransmitters, including acetylcholine, causing the connections between the synapses to weaken.

The hippocampus loses five percent of its neurons every decade, with twenty to thirty percent being lost by the age of eighty. Aging also causes changes in white matter, the part of the brain that contains the nerve cell fibers involved in relaying information.

The extent of memory deterioration, however, depends upon a variety of factors and can even be reversed to some degree. Favorable genetics, a healthy diet, low stress levels, physical exercise, and avoidance of alcohol and tobacco can significantly reduce the effect of aging on memory.

In addition, continued mental stimulation is vital; reading, drawing, and doing puzzles can stimulate the growth of dendrites that maintain strong connections between neurons. The best advice older people can heed is to treat the brain like any other muscle: “use it or lose it.”