By Chris Adams

When does happiness hit its low point? When does memory fade?

Darlene Howard, a professor emeritus in the Department of Psychology at Georgetown University, has been studying those questions during a lifetime of research into how the human brain changes over time.

Howard, who during her career worked at Georgetown’s Cognitive Aging Lab, reviewed the literature on memory loss and brain health, with an emphasis on how conventional wisdom on the topic has changed.

“The way we think about aging has changed dramatically in the past decade,” she said.

The old view, she pointed out: All cognitive functions decline with aging. Old brains operate the same way as young ones, only less efficiently. There is nothing we can do about age-related declines.

The new view: Cognitive loss is selective – it differs by function, and by person. Old brains often do things differently than old ones. People can do a lot to possibly prevent age-related declines.

How? Having a healthy diet. Being socially engaged. Meditating. And exercising – that’s vitally important.

“There is really good evidence that exercise – particularly aerobic exercise – improves cognitive function,” she said. In one experiment, participants exercised three days a week for at least 45 minutes, with some doing aerobic exercise and others stretching and toning. The aerobic participants scored better on cognitive tests.

People also need to keep in mind the wide variability in brain and memory performance. While average brain-processing speed declines over time, that’s just the average. “There are 80-year-olds who are faster than 20-year-olds,” she said. “There is just tremendous variability.”

She also talked about the “happiness curve,” which shows self-reported well-being hitting its nadir in the early 50s and going up steadily from there. Depression rates are highest in mid-life, and low in later years.

She also noted that Alzheimer’s disease isn’t just accelerated aging, and people can do a lot to delay the onset of symptoms. Being bilingual throughout your life is one way to do so – so head to a language class.