04 Mar Childhood Advantages Linked to Bigger Brain Reserves But Faster Cognitive Decline
MedicalResearch.com Interview with:
Marja Aartsen, PhD
Research professor at NOVA
Norwegian Social Research / OsloMet
Oslo Metropolitan University
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Our study is part of a larger project “Life course influences on health trajectories at older age” conducted at the University of Geneva, of which dr. Stéphane Cullati is the principle investigator (see for more information on the project https://cigev.unige.ch/index.php?cID=887). The aim of that research project is to examine in what way retrospective life course precursors from childhood to late adulthood have long-term impacts on current health trajectories at older age. A number of studies in this project are now published among which our study on childhood conditions and cognitive functioning and cognitive decline in later life.
In our research, we were particularly interested in the origins of cognitive decline in later life. Studies among children show that the childhood is an important phase in the development of the brain. Growing up in environments in which people are cognitively stimulated stimulates the brain to develop more complex neuronal networks and larger brain reserves, which may compensate for the neuronal losses that occur when people get older. This effect is long visible, even at old age as a number of important studies recently provided quite solid evidence for the beneficial effect of advantaged childhood conditions on level of cognitive functioning in later life. However, not many studies investigated the relation between childhood conditions and the speed of cognitive decline in later life. Those that did found inconsistent results. We reasoned that part of the inconsistencies in study findings might stem from differences in the analytical approach (not sensitive enough), too little cognitive change because of a short follow-up, too young people, or too small sample (all causing too little power to find statistically significant effects) or differences in the measurement of the childhood conditions. To overcome these potential limitations, we used a large study sample with long follow-up, used a multidimensional measurement of childhood condition, and applied a powerful analytical technique.
MedicalResearch.com: What are the main findings?
Response: In line with previous research, we observed that people with more advantaged childhood had higher levels of memory functioning and word fluency. Compared with people who had the most disadvantaged childhood, people in the most advantaged socioeconomic position could on average remember 1.27 more words and could mention 5.39 more animals in 1 minute time. Low scores on memory and word fluency has clinical relevance, as it can be an early sign of dementia. The negative effect of a disadvantaged childhood can be partly undone during the life course, if people follow higher levels of education, find jobs that are more complex and increase their wealth.
However, we also found that those in the most advantaged childhood conditions had a 1.6 times faster decline in later life than people with the most disadvantaged childhood conditions. We did a number of robustness checks to double-check our findings, but it did not lead to different conclusions. Although counter intuitive at first sight, the faster decline fits to theories about the cognitive reserve. People with an advantaged childhood develop larger brain reserves throughout their life, which helps to repair neuronal losses in later life and postpones cognitive decline until the underlying cognitive pathology, for example dementia, is substantial and speed of decline accelerated.
MedicalResearch.com: What should readers take away from your report?
Response: This research shows the importance of childhood conditions for cognitive functioning not only in adulthood, but also at higher ages. Our study also suggests that it is possible to postpone cognitive decline, even if people grow up in families with disadvantaged socio-economic conditions, as adulthood socio-economic conditions can partly compensate for the disadvantages people encountered in their childhood. Interventions to improve cognitive functioning and postpone cognitive decline may benefit from improvements in childhood conditions and improvement in socio-economic conditions during adulthood.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: For a more substantial understanding of cognitive functioning in later life and the origins of dementia, it is important to take into account the socio-economic conditions early in life. Conclusions with respect to associations with decline need to be drawn with caution if the study sample is small or if the study population is relatively young, as substantial power is needed to detect associations with cognitive decline.
MedicalResearch.com: Is there anything else you would like to add?
Response: This study was funded by the Swiss National Centre of Competence in Research “LIVES – Overcoming vulnerability: Life course perspectives”.
Proceedings of the National Academy of Sciences
Source Reference: Aartsen M, et al “Advantaged socioeconomic conditions in childhood are associated with higher cognitive functioning but stronger cognitive decline in older age” PNAS 2019; DOI: 10.1073/pnas.1807679116.
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