That is what a recent study by MPIDR researcher Angelo Lorenti and colleagues found by analyzing data from the U.S. Health and Retirement Study.
Participating in the labor market until the age of 67 slows cognitive decline and is protective against cognitive impairment, such as that caused by Alzheimer’s.
This protective effect appears to hold regardless of gender and educational or occupational attainment. These findings were recently published in the journal SSM Population Health.
The team of researchers with Jo Mhairi Hale, Maarten J. Bijlsma, and Angelo Lorenti, all affiliated with the Max Planck Institute for Demographic Research (MPIDR) in Rostock, Germany, used data from the Health and Retirement Study on more than 20,000 US-Americans ages 55 to 75 who participated in the labor market at some point between 1996 and 2014.
There are modifiable life-course predictors of cognitive function
With population aging there is a growing concern about increasing prevalence in Alzheimer’s disease. As there is no cure for Alzheimer’s, it is important to understand the influences on cognitive function over one’s life span, paying particular attention to modifiable risk factors.
“In this study, we approach retirement and cognitive function from the perspective that they both come near the end of a long path of life,” says Angelo Lorenti.
“It begins with one’s social origins in ethnicity, gender, and early-life social and economic status, goes on with educational and occupational attainment and health behaviors, and goes all the way up to more proximate factors such as partnership status and mental and physical health.
All these kinds of factors accumulate and interact over a lifetime to affect both cognitive function and age at retirement.”
What are the health consequences of postponing retirement?
“We investigated how demographic change interacts with social and labor market dynamics,” says Angelo Lorenti. In many countries governments have enacted policies to increase the statutory retirement age.
That is why it is relevant to understand if retiring at older ages may have health consequences, particularly on cognitive function. “Our study suggests that there may be a fortuitous unintended consequence of postponed retirement,” says Lorenti.
According to the ‘use it or lose it’ hypothesis, a lack of mentally challenging activities might exacerbate the loss of cognitive function. On this basis, retirement has been suggested to increase the risk of cognitive decline, but evidence from studies with long follow-up is lacking. We tested this hypothesis in a cohort of 3433 civil servants who participated in the Whitehall II Study, including repeated measurements of cognitive functioning up to 14 years before and 14 years after retirement.
Piecewise models, centred at the year of retirement, were used to compare trajectories of verbal memory, abstract reasoning, phonemic verbal fluency, and semantic verbal fluency before and after retirement. We found that all domains of cognition declined over time. Declines in verbal memory were 38% faster after retirement compared to before, after taking account of age-related decline.
In analyses stratified by employment grade, higher employment grade was protective against verbal memory decline while people were still working, but this ‘protective effect’ was lost when individuals retired, resulting in a similar rate of decline post-retirement across employment grades. We did not find a significant impact of retirement on the other cognitive domains.
In conclusion, these findings are consistent with the hypothesis that retirement accelerates the decline in verbal memory function. This study points to the benefits of cognitively stimulating activities associated with employment that could benefit older people’s memory.
Discussion
In this longitudinal study of 3433 individuals, we compared cognitive decline before and after retirement and examined whether trajectories varied depending on employment grade. We found that declines in verbal memory were faster during the 14 years after than during the 14 years before retirement.
In the stratified analysis, we found that higher employment grade may be protective against verbal memory decline while people were still working, but this ‘protective effect’ was lost when individuals retired. The other domains of cognitive function, including abstract reasoning, phonemic verbal fluency, and semantic verbal fluency, were not affected by retirement, but declined steadily with age.
Our finding showing an adverse effect of retirement on verbal memory is consistent with most previous studies which used instrumental variables [18–21] and also those which have applied other statistical methods. For instance, Wickrama and O’Neal [35] used growth curve analyses in the USA Health and Retirement Study (HRS), and found that individuals who retired between 1998 and 2002 had a faster memory decline between 2002 and 2006 compared to those who were working at both instances.
In another HRS investigation, Clouston and Denier [22] showed similar findings for retirement and episodic memory (comprised of both verbal learning and verbal memory) by using longitudinal regression discontinuity methods to analyse trajectories between 1998 and 2012. A cross-national study by Adam et al. [55] used the stochastic frontier approach to estimate the episodic memory that individuals would reach if they were fully efficient for a given level of resources.
They found an adverse effect of retirement on episodic memory and highlighted the positive impact non-professional activities at retirement and increased social contacts could have for episodic memory.
Our finding on the retirement-associated decline in verbal memory supports the ‘use it or lose it’ hypothesis suggesting that failing to keep mentally active may accelerate the rate of cognitive decline in post-retirement periods [17]. On a similar note, our findings are also consistent with the theory of ‘mental retirement’ proposed by Rohwedder and Willis [21], suggesting that the work environment could be more cognitively stimulating than the leisure environment as a retiree.
Besides the direct effects of an absence of cognitive activities related to work, retirement may also affect cognitive function indirectly via loss of work-related forms of self-organisation, communications and collaborations [56], which are important factors potentially contributing to the maintenance of cognitive reserve [55, 57]. For example, social networks could be more extensive during employment, and accordingly, Börsch-Supan and Schuth [58] estimated that at least one-third of the decline in cognition after retirement could be attributed to a reduction in the size and composition of social networks.
Our results showing a significant effect of retirement for verbal memory but not for other cognitive domains suggest that retirement may affect some cognitive domains more than others. Age-related neuronal modifications that are at the root of Alzheimer’s disease have been observed to have heterogeneous effects on cognitive functioning.
For example, episodic memory deficits are largely considered as a hallmark symptom of Alzheimer’s disease [59], but this is less the case for other domains of cognition. It may also be that verbal memory is a more sensitive indicator of cognitive decline than the other indicators. Few studies have assessed the effect of retirement on different domains of cognition.
Using the USA Wisconsin Longitudinal Study, Denier et al. [60] found that those who had retired voluntarily or for family reasons had improved reasoning abilities, which is contrary to our findings. Denier et al. used the similarities construct of the Weschler Adult Intelligence Scale to measure reasoning abilities. Respondents were asked to relate two words; for instance, ‘How are an apple and orange alike?’ to which they should respond that both are fruits.
In contrast, the AH4 questionnaire used in our study consists of both verbal and mathematical questions. Inconsistent results may originate from different assessments of cognitive functioning across studies. One SHARE study tested only memory and numeracy and found that both domains were negatively affected by retirement [58].
Also using SHARE data, Mazzonnaa and Peracchi found that retirement was negatively associated with verbal memory, orientation, and numeracy for both men and women. Retirement was not associated with verbal fluency, with the exception that retired women without a high-school degree showed a faster decline in verbal fluency [20].
Our Whitehall II study did not measure orientation or numeracy, but our results of the negative effect on memory and no influence on verbal fluency are generally consistent with these two SHARE studies. Roberts et al. [36] previously used Whitehall II to show that mean cognitive test scores increased between two assessments over 5 years, and discussed that this is possibly due to practice effects. They found that those retired increased less than those still working.
Their findings could not be confirmed by our study using longer follow-up of Whitehall II, where we have taken account of practice effects by adjusting for the number of cognitive tests a participant has completed in previous phases.
Stratified analyses showed that higher employment grade may be protective against cognitive decline while people were still working, but this ‘protective effect’ went away when individuals retired. According to the cognitive reserve hypothesis, engagement in mentally challenging activities can yield additional neuronal resources that may prevent cognitive decline [57].
Higher grade jobs have higher levels of skill discretion implying more opportunities for the use of skills and variety of work [37], which suggests higher levels of mental processing than clerical/support jobs. Thus, our observation that employees in higher grades had slower decline during employment is plausible.
This protection of higher grades no longer exists after retirement. As expected by the ‘use it or lose it’ hypothesis, the decline in verbal memory was similar in all participants irrespective of their pre-retirement employment grade.
Our findings on employment grade are in agreement with the observations from SHARE, showing that the average effect of retirement on cognition was negative, and the negative effect of retirement disappeared when the sample was restricted to people who worked in more physically demanding occupations [61]. Our stratified results are also in line with Finkel et al.’s work, which found that retirement from more complex jobs was related to a faster rate of cognitive decline in the longitudinal Swedish Adoption/Twin Study of Aging [62].
However, Fisher et al. [30] found that participants from occupations characterised by higher levels of mental demands showed slightly higher cognitive performance and less steep decline both before and after retirement, compared with individuals who were engaged in fewer mental demands.
It is likely that employment grades may not only represent job mental demands but also serve as an indicator of broader working environments as well as post-retirement financial resources and social support. People in higher employment grades may have a stronger attachment to their work role, and thus retirement may be more detrimental to them because of this role loss. Future studies might investigate different preretirement occupational characteristics in order to understand the nature and mechanisms underlying the cognitive effects of retirement.
Our findings on employment grade should be interpreted cautiously because only 12.1% of our analytic sample was retired from clerical/support grade, and the interaction by employment grade was only marginally significant.
Therefore, we cannot rule out the possibility that the different results found for clerical/support grade were due to selection bias. It is also worth pointing out that, even though individuals in higher grades had a faster rate of cognitive decline after retirement compared to before retirement, they still had higher average levels of cognition than people in the lowest grade, both before and after retirement. This suggests that although retirement seems to be more detrimental for those in higher grades, people in the lowest grade remain at greatest risk of developing cognition problems.
We found no significant sex differences in terms of the effect of retirement on verbal memory. However, less than 30% of our sample are women, with even fewer women in the higher grades, so it is possible that the study lacked the power to detect potential sex differences.
reference link :https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6153553/
More information: Jo Mhairi Hale et al, Does postponing retirement affect cognitive function? A counterfactual experiment to disentangle life course risk factors, SSM – Population Health (2021). DOI: 10.1016/j.ssmph.2021.100855
