Brain blog showcase 2021: Occupational experiences may be associated with poorer memory and smaller memory structures within the brain

This week we’ve been showcasing the work of students who have been “researching the headlines” as part of their undergraduate studies. Their task was to describe an original research report exploring how lifestyle affects brain health in a manner accessible to non-experts, as well as evaluating the media coverage of the research. If you’re interested in using this approach in your own teaching, you can contact Alan Gow for more information and materials.

For our final “brain blog”, we have…

Occupational experiences may be associated with poorer memory and smaller memory structures within the brain

by Hayley Syme

Physical activity is often thought to be beneficial for our brain health. So, we might assume that regardless of the context the physical activity occurs in, we will benefit from it. Yet, a recent study has reported an association between physical demands in the workplace bearing negative consequences related to memory and hippocampus volume in older age. The study also gained the interest of journalists, with the study being reported on by the New York Times. With many of us working for the majority of our lives, the findings may have wide-reaching implications. Before you begin writing your letter of resignation, it is important to take a closer look at the original research findings and assess the accuracy of the media reporting.

What did the original research article tell us?

The research article, published in Frontiers in Human Neuroscience in July 2020, was conducted by a team of researchers across universities in Iowa, Illinois, Boston and Colorado in the United States. The authors make the case that many of us spend the majority of our lives working and so, our occupational experiences must contribute to our cognitive ability in later-life. They were particularly interested in looking at whether participants subjective occupational experiences might be related to scores on tests of memory and the size of their hippocampus, which is an area within the brain associated with memory.

To test this, the researchers recruited participants who had previously taken part in a clinical trial in 2014. The 99 participants were aged between 60-80 years old and were asked to complete three questionnaires based upon their most recent job that they worked in for at least 2 years. The questionnaires assessed job complexity, psychological stress and physical stress. The participants then completed tests of cognitive function (memory tests, vocabulary tests, reasoning and tests of processing speed). Finally, participants were asked about their leisure physical activity and asked about their general stress experienced out-with their job. By taking part in a clinical trial years before, the researchers were able to compare scores on tests of cognitive ability and look at images of their hippocampus obtained from their brain scans.

In summary, the research paper found that those who reported having more physically taxing jobs, had smaller hippocampi and poorer scores on tests of memory. Interestingly, there was a very weak but positive association between occupational stress and hippocampal volume. In addition to these findings, leisure physical activity was positively associated with hippocampal volume. So, those that engaged in more physical activity outside of work had larger hippocampi and performed better on tests of memory. The findings suggest then that leisure physical activity seems to be beneficial, but the effects are opposite for physical activity the workplace.

What did the media report tell us?

Overall, the media report published by the New York Times captures the main findings of the research article fairly well. The author acknowledges that the findings are thought-provoking but do not prove that physically demanding jobs “shrink” our brains. This is particularly good and shows careful consideration of the consequences of allowing readers to believe that the findings are more than an association.

With that said, however, there are some issues with the wording used to report the findings of the original research article. The author, for example, states that the researchers found no relationship between thinking on the job and “better brain structure”. This sentence is confusing to use when investigating the brains of cognitively normal and healthy older adults. The use of the word “better” implies that a smaller hippocampus is associated with abnormal changes in the brain. However, the original research article acknowledges that as we grow older, our hippocampus undergoes a reduction in volume, and this is part of the normal ageing process (i.e. is not the result of age-related diseases such as Alzheimer’s). The author mentions the word “brain” on several occasions when reporting the findings of the research. Whilst we can forgive the author for opting to use the word ‘brain’ in place of ‘hippocampus (it is a lengthy and strange sounding word), there is a big difference. This is especially important to distinguish as the researchers did not find reduced overall brain size in participants but were looking at the hippocampus in particular because of its role in memory.

Should you hand in your notice of resignation?

The short answer is no. Whilst the research draws some interesting conclusions, the study only finds an association between reduced hippocampus volume and poorer scores on memory tests for those who reported having physically demanding jobs. This does not mean physically demanding jobs were the cause. This is especially true as participants gave their own accounts of how physically demanding their occupation is/was. What might be physically demanding for one person, may not be to another. Additionally, the sample used in the study was small, so they may only be applicable to the participants in the study. On the brightside though, the study did find an association, albeit small, between leisure physical activity and hippocampus volume. So, perhaps the solution after a long week of work is to find that Jane Fonda workout video, wipe the dust off and counteract the potentially negative impact of our working week through leisure physical activity.

References

Burzynska, A. Z., Ganster, D. C., Fanning, J., Salerno, E. A., Gothe, N. P., Voss, M. W., McAuley, E., & Kramer, A. F. (2020). Occupational Physical Stress Is Negatively Associated With Hippocampal Volume and Memory in Older Adults. Frontiers in Human Neuroscience, 14, 2–9. https://doi.org/10.3389/fnhum.2020.00266

Reynolds, G. (2020, August 6). Can a Physically Taxing Job Be Bad for Our Brains? The New York Times. https://www.nytimes.com/2020/08/05/well/move/can-a-physically-taxing-job-be-bad-for-our-brains.html