Mental Decline Starts around 45

Most of us have accepted that there’s likely to be some loss of mental faculties in old age, but we also hope that we’ll dodge the devastation brought by Alzheimer’s disease or other forms of dementia.  In recent decades, however, researchers have demonstrated ‘cognitive decline’ as part of the normal aging process.  Now we learn that this sets in much earlier than we expected.  This is brought out in a study from University College, London, and published online in the British Medical Journal.

Data came from the Whitehall II Study, in which 5,000+ men and 2,000+ women who were aged 45 to 70 at enrollment in 1997-1999 were followed for 10-year periods.  During this time they underwent tests of memory, reasoning, vocabulary, listening skills, and recall, three times over a 10-year period.

The participants were classified into 5 age categories according to their baseline age: 45-49, 50-54, 55-59, 60-64, and 65-70 years.  All the cognitive test scores, except vocabulary, showed declines in all 5 age categories.  Moreover, there was faster decline in the older categories.  For instance, the 10-year decline in reasoning ability in men aged 45 to 49 at baseline was -3.6%, while it was -9.6% in men aged 65-70 at baseline.  In women, the corresponding decline was -3.6% and -7.4% for the same two age categories.

All the participants were civil servants, i.e. government office employees; and most of them were white and married.  However, it’s highly likely that these findings are applicable to other races and social categories.

What are the implications of this new knowledge?  It’s known that lifestyle factors and cardiovascular risk factors affect the likelihood of earlier cognitive decline.  However, now that we know that the problem starts at 45 (or thereabouts), it’s clearly important to address such factors as high blood pressure, overweight/obesity, and high cholesterol levels at an age when their control are most likely to be beneficial for cognitive function, i.e. before degeneration of nerve cells has begun. . .