Cognitive Decline at 45: Fact or Fiction?

Several news stories have appeared in the past month regarding this research study, based on the Whitehall II cohort project, which has followed the overall health of several thousand British civil servants since 1985. Most of the news stories use mildly alarmist terms like “Mental Decline Starts at 45” and “Sorry, Boomers, but a new study suggests that memory, reasoning and comprehension can start to slip as early as age 45.

The study used a cognitive testing battery called Alice Heim 4-I for executive function (logic) skills, plus other tests for memory and vocabulary ability. All of the tests are reasonable choices made by the research team.

But here’s the problem with reading too much into the study results: there are hundreds (if not thousands) of cognitive tests that are used in research studies around the world in any given year, and most of them are different in content, length and scoring. This means it’s difficult to compare or translate what “decline” really means outside of that specific study.

What has been confirmed at a general level, however, is an age related change in performance in the following areas:

  1. Response time/reaction time increases. This is why 18 year olds are better at quick reaction video games compared to the average 50 year old.
  2. Processing speed decreases. Processing speed is a combination of sustained attention + assimilating new information in an efficient manner. Older adults can of course learn new skills and abilities, but it tends to be at a somewhat slower pace than when they were 25. The limiting factor is “machine noise”, a term Dr. Mike Merzenich at the Brain Plasticity Institute uses to describe the nature of an older brain. This is usually balanced out by experience and acquired knowledge, sometimes also known as wisdom.

As with any well-used item, preventive maintenance is important to keep it in good working order: readers can follow these four tips to help maintain a healthy brain.

Also, try your hand at these free working memory and cognitive function tests. Cognitive training has been shown to improve both response time and performance speed with repeat training.