A study led by a team from the Institute of Neurosciences of the UB identified greater cortical thickness in the frontal lobe in a group of old people with high levels of education (15 or more years of education). Afterwards, the study of the molecular architecture of these regions revealed these areas feature a relative overexpression of gene families involved in the synaptic transmission and the activation of the immune response. Results provide new data on humans regarding potential molecular mechanisms that may explain how high levels of education are associated with the preserved cognitive function in the elderly.
The total number of years of education is the most common proxy measure of cognitive reserve, a psychological construct that reflects the capacity of the adult brain to counteract or minimize the cognitive impact of the typical effects of ageing (i.e. brain atrophy) and even of the initial stages of neurodegenerative conditions such as Alzheimer's disease.
This is stated in a study published in The Journal of Neuroscience, led by David Bartrés-Faz, adjunct lecturer at the Faculty of Medicine and Health Sciences and researcher at the Institute of Neurosciences of the UB (UBNeuro) and the August Pi i Sunyer Biomedical Research Institute (IDIBAPS), together with the team led by Dr. Michel J. Grothe, from the German Center for Neurodegenerative Diseases (DZNE) and published in The Journal of Neuroscience, the researchers, using magnetic resonance data, analysed the brain regions that differ in cortical thickness among older adults with high figures of years of education (15 or more years) compared to a group of individuals with a lower number of years of education.
"This analysis suggested the group of people with more years of education presented greater cortical thickness in the frontal lobe, particularly in the prefrontal areas of the anterior cingulate cortex and the orbital cortex", says David Bartrés-Faz. In a second part of the study, researchers analysed whether these regions were featured, at a molecular level, by a different genetic expression profile than the other areas in the brain. To do so, researchers used data from the Allen Institute Human Brain Atlas, which contains information on the cerebral cortex' human transcriptome. "What we saw -notes Bartrés-Faz is that, compared to the other regions of the cerebral cortex, the areas where people with higher levels of education show a major cortical thickness are characterized by an overexpression of gene families involved in synaptic transmission-, and therefore, in brain plasticity mechanisms, as well as in gene families involved in immune responses".
"The results are relevant because they reflect -for the first time- the molecular features of brain areas in humans that vary in thickness depending on the education these people received. More specifically, these data are relevant because they conciliate previous studies which suggested education modulates brain plasticity mechanisms. According to Bartrés-Faz, "the identified molecular evidence regarding the overexpression of gene families linked to neurotransmission systems suggest this effect", says the researcher.
Previous studies on neuroimaging had already shown that prefrontal regions such as the anterior cingulate and orbital cortex increased metabolism and functional connectivity in old people with high levels of cognitive reserve. These results had been understood as reflecting greater neural efficiency or higher compensatory capacity to counteract brain atrophy and damage in these elderly. The new study is compatible with these interpretations, while providing new directions for future molecular studies on brain health in ageing.
The study has been carried out analysing neuroimaging data 122 cognitively normal older adults (87 women and 35 men, average age of 68.2), including participants from the study Walnuts and Healthy Ageing (WAHA), coordinated by Dr. Emili Ros, from the Service of Endocrinology and Nutrition at Hospital Clinic de Barcelona-IDIBAPS and the Physiopathology of Obesity and Nutrition Networking Biomedical Research Centre (CIBERobn).