Verbal memory function declined 38% faster after retirement than before, in a new study analyzing cognitive function in retired civil servants. Other important cognitive functions, such as the ability to think quickly and identify patterns, were found to be largely unaffected.
It’s not clear whether the faster decline of verbal memory function had meaningful clinical significance. It certainly doesn’t prove that people were more likely to develop dementia.
Verbal memory function is the ability to recall words, names and other spoken information. Memory decline is a complex problem affected by many different factors, not just retirement. Staying active during retirement may also help to improve overall quality of life, maintain social networks and help prevent loneliness.
The Whitehall II Study
The study, conducted by researchers at University College London, King’s College London and Queen Mary University, looked at data from 3,433 people from the Whitehall II Study. This is an ongoing prospective cohort study looking at wellbeing and mental and physical illness in an ageing population.
Large prospective cohort studies such as this are a good way of looking at a large body of data to see whether different exposures may be linked with later outcomes. However, the best sort of study will set out with the purpose of examining the influence of a specific exposure or risk factor to ensure they have gathered the right information and assessed possible confounders.
This study wasn’t specifically set up to look at the effect of retirement on cognitive decline. This means the authors can suggest association, but they can’t rule out confounding from other factors.
[caption id=“attachment_94262” align=“aligncenter” width=“680”] Trajectories of abstract reasoning
Credit: Baowen Xue, et al. CC-BY[/caption]
The Whitehall II Study recruited civil servants aged 35-55 working in the London offices of 20 Whitehall departments in 1985-1988. The response rate was 73% resulting in a sample of 6,895 men and 3,413 women. The participant’s employment ranged from clerical grades, through to senior administrative grades.
This particular study looked at data collected every 2 to 3 years between 1997 and 2013 (4 waves in total) when information on cognitive function was collected. This analysis included 3,433 people (72% male) who moved from work to retirement and had cognitive assessment at least once before and once after retirement.
At each of the 4 assessments self-reported employment status, memory and health status were measured. The memory examinations tested people’s:
verbal memory (memory for words and verbal items)
abstract reasoning (ability to think quickly and identify patterns)
verbal fluency (retrieve specific information)
The researchers looked at the relationship between retirement and cognitive function, adjusting for the following confounders:
year of birth
total blood cholesterol
They also looked at whether retirement was due to long-term sickness, which was defined as health-related retirement.
Verbal memory was the only cognitive outcome linked with retirement after adjusting for age and other confounders. Retirement had no significant impact on the other cognitive domains.
Declines in verbal memory were 38% faster after retirement compared to before. After retirement, verbal memory scores declined by 0.143 every year (95% confidence interval [CI] -0.162, -0.124). The scores are based on how many of 20 words the participants could recall after 2 minutes.
Higher employment grade was protective against verbal memory decline while people were still working, but this was lost when individuals retired, resulting in a similar rate of decline post-retirement across employment grades.
Use It Or Lose It
The researchers wrote:
“In support of the ‘use it or lose it hypothesis’ we found that retirement is associated with faster declines in verbal memory function over time, but has little impact on other domains of cognitive functions, such as abstract reasoning and verbal fluency."
This study has some strengths in that it was able to assess a large number of people and look at cognitive change over a long time period, both before and after retirement. It also took into account a number of important factors that may be confounding the analyses.
However, this study only showed a decline in verbal memory. It had no effect on other areas, so certainly doesn’t show that people are at risk of faster overall cognitive decline after retirement. It also doesn’t show any links with a clinical diagnosis of either mild cognitive impairment or dementia.
It’s unclear whether the 38% greater decline in verbal memory would make meaningful difference to a person’s everyday life. The study also can’t show that retirement is the direct cause of the greater decline because other factors may be involved. However, it is possible.
Verbal ability is likely to be enhanced in the work environment due to the need for self-organisation, communication and collaboration. Therefore it may be fairly normal for this to be poorer after retirement.
Staying physically and mentally active, with a good social network, can help to maintain overall quality of life and wellbeing. This may also help to maintain cognitive function.
The research was funded by the Economic and Social Research Council and the Medical Research Council.
Xue, B., Cadar, D., Fleischmann, M. et al. Effect of retirement on cognitive function: the Whitehall II cohort study Eur J Epidemiol (2017). https://doi.org/10.1007/s10654-017-0347-7
Top Image: Philippe Put/Flickr