Loss of memory and other cognitive functions might start much earlier in life than previously thought, according to a clinical study from England.

A modest decline of mental abilities such as reasoning and problem-solving was found in participants who were only in their 40s.

For the study, researchers tested 7,000 men and women over a period of 10 years for memory, vocabulary and aural and visual comprehension. The results showed an average of 3.6 percent decline in reasoning skills in both sexes at the age of 45 to 49. 65 to 70 years old men showed on average a steeper decline than women of the same age group – 9.6 versus 7.4 percent.

Since the youngest participants were 45 years old when the study began, it is possible that the deterioration of brain functions might commence even earlier, according to Dr. Archana Singh-Manoux, the leader of the research, which was co-sponsored by the Center for Research in Epidemiology and Population in France and the University College London. The results were recently published in the “British Medical Journal.”

Previous studies on age-related decline of mental health have primarily focused on people in their sixties, seventies and beyond. By limiting ourselves to a narrower scope, we might not yet have gotten the entire picture, according to Dr. Singh-Manoux. A decline of mental capacity doesn’t suddenly happen at old age. That variability exists much earlier on, she says.

Researchers still need to learn more about the risk factors that lead to progressive cognitive impairment. There is strong evidence that Alzheimer’s disease and other forms of dementia is closely related to heart disease, which is typically caused by weight problems, high blood pressure and high cholesterol.

We probably underestimate how affected the broader population may be, says Dr. Singh-Manoux. The participants in this study were drawn from a relative homogeneous pool of office workers who were well educated and, for the most part, enjoyed a comfortable life and good health. This is not necessarily a representative profile at a time when so many suffer from obesity and other lifestyle-related health issues.

Although the causes of mental decline are not yet fully understood, experts recommend a number of measures that may not prevent but at least slow down the process. These include regular physical exercise, healthy nutrition, weight control, intellectual activity, avoidance of smoking and alcohol/drug abuse, stress reduction, sufficient amounts of sleep as well as social activities and supportive relationships.

A study conducted by the Mayo Clinic concluded that engaging in stimulating mental activities through reading, discussion, playing challenging games and other interactions can help decrease the risk of cognitive impairment significantly. This does not only apply to the elderly. To prevent even mild cognitive impairment (MCI), it is important to “exercise” the brain at any age.

“This study … demonstrates that aging does not need to be a passive process,” says Dr. Yonas Geda, a Mayo Clinic neuropsychiatrist and lead author of the study report. “By simply engaging in cognitive exercise, you can protect against future memory loss.”

To what degree we actually hold the key to our mental health remains to be seen. Preserving our physical health as best as we can is certainly a good strategy. Baby boomers have long been spending millions to save their sagging skin, fix their crow’s feet and plump their lips. As they reach old age, they finally are beginning to turn to brain boosters to fight memory loss, writes Virginia Anderson of WebMD in an article titled “Seven Brain Boosters to Prevent Memory Loss.” In fact, the process may begin much earlier in life and people need to pay attention before it’s too late.

Timi Gustafson R.D. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog, “Food and Health with Timi Gustafson R.D.” and at amazon.com. You can follow Timi on Twitter and on Facebook.