Changes in Brain Size with Aging

Understanding brain aging has to be research priority. The average age of people in the US is increasing. This means that there are more older people at risk for diseases that occur as people get older, such as Alzheimer’s.

In people, the size of the brain decreases as they get older. The deep grooves on the surface of the brain (called sulci) get bigger, and the fluid-filled areas inside the brain (ventricles) get larger. It all amounts to loss of brain tissue, and many people believe that this loss of brain tissue may be related to cognitive changes that also occur with aging, like problems in remembering things.

That’s why a recent study about brain size in chimpanzees is interesting. It shows that chimpanzees, who in many respects are similar to humans, have brains that don’t get smaller as they get older. Chimpanzees also don’t live as long as humans. The authors of the study argue that the decrease in brain size with increasing age that is seen in humans may have something to do with how long humans live. They suggest that the longer life span of humans may be in part the result of an evolutionary trade-off in which increased life span may have the cost of increased age-related neurodegeneration.

Reference:

Sherwood CC et al. Aging of the cerebral cortex differs between humans and chimpanzees. Proceedings of the National Academy of Sciences, PNAS early edition (online) DOI: www.pnas.org/cgi/doi/10.1073/pnas.1016709108

4 Myths About the Brain and Aging

When I give talks about brain fitness, I often start off by telling the audience that it wasn’t that long ago that all of us in professional schools were taught that we are all born with a certain number of brain cells and that they start dying off as soon as we are born.

Then I talk about the exciting research in the past few decades that shows that new nerve cells can grow in parts of the brain critical for learning and memory. Instead of relentless decline toward death, the reality may be a continuing cycle of change and renewal throughout life.

That has led me to think of 4 particularly important myths about the brain and aging:

• The number one myth is that brain aging is strictly a biological process that is controlled by a person’s genetic makeup and that can’t be affected. The brain, like the rest of the body, is an organ that exists in a dynamic relation with the environment. The brain is affected, for better or worse, by what see, hear, think, and do, as well as by diet, exercise, stress, and sleep.
• Another myth that arises from the number one myth is the idea that there’s nothing we can do about age-related changes in how our brain function. Although the study of interventions to affect cognitive aging is still new, the evidence is pretty clear that exercise, diet, and mental and social activity can have potent effects on how your brain ages.
• As much as I enjoy crossword puzzles, I think one of the most pernicious myths about brain aging is the idea that simply doing intellectually-stimulating activities is enough. A related myth is that simply completing a course of computer-based cognitive training will take care of age-related changes. Although there’s even less hard data on combinations of treatment, the most successful interventions are multifactorial and include lifestyle changes as well as mentally stimulating activities.
• Finally, one of the most important myths about the brain and aging is that all changes in the brain and mental functioning are bad. An important line of research in cognitive aging shows that some mental functions are better or different with age. Older persons, for example, may make decisions better. They may be better able to discern patterns in a difficult situation, and may have superior knowledge about people and how they react.