Memory can also diminish with age, though only certain types. Learned skills such as driving are wired so firmly that they typically do not decline unless you have a disease such as Alzheimer's. Memory for events (called explicit memory) is a bit more vulnerable, although episodes that really made an impression, such as meeting your spouse, are generally secure.
If your memory is suffering, it's most likely your short-term memory. This ability—which includes "working memory," where events are held before being filed for the long term—usually peaks by the early 30s. That's why memorizing complex new information, such as a foreign language, can get harder as you get older.
So how do you keep your brain at its best? By growing new brain cells, for starters. Long thought impossible, this turns out to be relatively routine in lab animals and, thus, maybe in humans. Scientists suspect that certain lifestyle habits can spark the cells' growth.
In 1998, Fred Gage, Ph.D., and his colleagues at the Salk Institute for Biological Studies in La Jolla, California, showed that the memory centers of adult human brains can grow new cells. Since then, studies by Gage and others have suggested that the more physical and mental exercise you get, the more brain cells you grow, the longer they survive, and the better they connect with other nerve cells. Exercise, such as brisk walking for 40 minutes four times a week, increases bloodflow to the regions of the brain shown able to grow new cells. "In our lab, when we discovered this, people started taking walks during their lunch hour," says Gage. Movement is so crucial to brain health that some of the cognitive changes blamed on aging may in fact be the result of inactivity, he adds.
Another simple, brainpower-boosting habit: pay attention to what you're doing. As we age, we become more prone to distraction, thanks to some of the same brain changes that can hamper our thinking speed. But even a split-second loss of focus can prevent a memory from being properly stored. So when you put down your glasses, focus on where you put them; they may be a whole lot easier to find.
Many memory problems stem from treatable conditions such as vitamin B deficiencies, depression, thyroid problems, or uncontrolled vascular disease. So if you notice changes, a visit to the doctor could set you straight.
If you're worried about your response time, practice can help quite a bit, researchers have found. After a group of people 65 and up did exercises in which they searched for and matched images, 87 percent of them improved their speed, according to a multicenter study led by the University of Alabama. And older adults who regularly tutored elementary-school students saw improvements in their own cognitive function after six months, a 2009 Johns Hopkins study showed.