Even Middle-aged Adults Experience Cognitive Decline, Says Study

The increasing lifespan of humans poses significant societal challenges in the years ahead, not the least of which will be providing care for an ever-growing elderly population. Given that poor cognitive status is arguably the single most disabling condition seen in older adults, clinical investigators have long sought to better understand the decline of cognitive function that accompanies the aging process.

Although previous research has clearly demonstrated marked cognitive deficits in adults ages 65 and older, the question of precisely when cognitive decline begins remains subject to debate. Now, a new study contends that cognitive decline can be detected in people as young as age 45.

The study, published Jan. 5 in BMJ, used data drawn from the Whitehall II cohort established in 1985. At the time that cognitive data collection began in 1997, nearly 7,400 adults ages 45 to 70 remained in the cohort. To allow comparison of cognitive decline as a function of age, participants were categorized into the following age groups: 45-49, 50-54, 55-59, 60-64 and 65-70.

The cognitive tests administered assessed verbal and mathematical reasoning, short-term verbal memory, verbal fluency (i.e., phonemic and semantic fluency), and vocabulary. The same battery of tests was given three times in the course of 10 years.

The results showed measurable amounts of cognitive decline across all age groups and in all the test areas except for vocabulary. Researchers found some evidence of greater decline at older ages and of a linear trend in decline with increasing age for some of the tests, particularly in men.

For example, in men ages 45-49 at baseline, the 10-year decline in reasoning was estimated to be 3.6 percent compared with 9.6 percent for men in the 65-70 age range. In women, the corresponding decline was 3.6 percent in those ages 45-49 at baseline and 7.4 percent in those ages 65-70.

"Adverse cognitive outcomes like dementia are now thought to be the result of long-term processes over at least 20-30 years, leading some authors to argue for the importance of approaches during life," the study authors note. "Despite much research on early diagnosis, pathophysiological and clinical studies have yet to identify biomarkers or cognitive profiles that accurately predict dementia. Nevertheless, there is enough evidence to show the importance of healthy lifestyles and cardiovascular risk factors in adulthood for dementia."

Given the fact that risk factors such as obesity, hypertension and high cholesterol have been identified as leading causes of dementia, it seems prudent for middle-aged patients with these risk factors to work with their physicians to address them early on. As the authors note: "There is emerging consensus that 'what is good for our hearts is also good for our heads,' making aggressive control of behavioral and cardiovascular risk factors as early as possible key targets for clinical practice and public health."