Cécilia SAMIERI PhD Epidemiology of brain aging and dementia, director of research at INSERM

Course and current status

After a doctorate in veterinary medicine, I obtained a doctorate in Epidemiology and Public health from University of Bordeaux (France) in 2009. I trained as a post-doctoral fellow at the Channing Division of Network Medicine, Harvard Medical school (Boston, USA). Back in France, I joined the INSERM (French National Institute for Health) as a tenured researcher in 2015, in the Bordeaux Population Health (BPH) research center INSERM U1219. As one of the PIs of the VINTAGE (Vascular and neurological diseases: integrative and genetic epidemiology) team, I lead a research theme on the exposome of brain aging and dementia. I have served as academic co-chair of the Alzheimer’s Association's Professional Interest Area group on Nutrition and Metabolic Diseases from 2019 to 2021 (now immediate past co-chair).

Scientific summary

The life-course history of environmental exposures is a strong determinant of chronic diseases. My research focuses on the epidemiology of brain aging, with the main objective of understanding how environmental factors, including nutrition and cardiometabolic health, influence the etiology of age-related brain diseases, such as dementia and its leading cause, Alzheimer's disease. I have worked on several large cohorts on dementia and cognitive decline, studying with a holistic view the influence of lifestyle on brain health, from overall lifestyle and dietary patterns to molecular markers of the exposome. I have led several national and international projects on the environmental risk factors of brain aging with a multidisciplinary approach across nutrition, neurosciences, applied biostatistics, brain imaging and molecular epidemiology. Over the past years, I have evidenced protective associations of: fish and marine omega-3 fatty acids; olive oil; healthy diets and related nutrients and metabolites; optimal cardiovascular health level; with healthy brain and general aging.

After years of research led by my group and others on environmental exposures and brain health, the environmental etiology of age-related brain diseases remains poorly understood, which may have hampered our way to design effective preventive strategies. The network and dynamics of environmental factors leading to age-related brain diseases has yet to be elucidated. There is a need for a novel epidemiological appraisal of the exposome through molecular biomarkers, with refining assessment of already-known exposures (eg, diet biomarkers), exploring novel exposures (eg, chemical mixtures), investigation beyond individual exposures (eg, microbiome interactions) and modeling the global exposome network, to improve etiological modeling of age-related brain diseases and identify the most impactful targets for prevention.

The research theme on the “Exposome of brain aging and dementia - A model for exploring the role of environmental risk factors using high throughput molecular approaches” (BPH INSERM U1219, VINTAGE team) leverages molecular epidemiology, brain imaging and advanced statistical approaches (eg, network modeling) deployed to population-based cohorts with biobanks in order to investigate: (1) the exposome of brain health at key ages, and (2) the underlying pathways and life-course dynamics.

With my group, we have initiated novel research on the exposome of brain aging, exploring, in older persons aged 65+ from the Three-City (3C) cohort, molecular markers of diet using untargeted metabolomics and complex diet patterns using network methodologies. We now aim to extend this research in two ways: 1/ investigate more deeply exposome biomarkers using high-throughput techniques (eg metabolomics) including, non-exhaustively: food contaminants, the chemical exposome and the microbiome; and incorporating some cross-organ pathways (eg, the heart-brain axis, the gut-brain axis) and systemic pathways (eg, the lipidome) through an integrative modeling of omics and brain imaging markers;  2/ target younger populations capitalizing on the B cube (Brain Health and Biobank in Bordeaux) and the i-Share cohorts. The B cube cohort is a new population-based cohort launched in early 2022, of 2000 participants aged 55-80 years from the community living in Bordeaux metropole (https://cohorte-b-cube.fr/). Home interviews will be conducted to record multiple exposome-related and health information, a cognitive battery, and collection of blood, urine, stool and salivary samples stored in a biobank. Research perspectives of the B cube cohort are multiple, our ambition being to set up a new epidemiological platform for research on determinants and the natural history of brain aging through molecular epidemiology and deep phenotyping. The i-Share study (PI: C. Tzourio), is a large ongoing cohort of students aged 18 to 35 years-old, among which approximately 2000 students participated into constitution of a biobank and underwent a brain MRI, opening unprecedented opportunities for novel investigations of the exposome and brain health during brain maturation in early adulthood.

These unique resources will allow us to decipher the dynamical relationships of environmental exposures with biomarkers of brain aging over the life-course, to characterize the age ranges of specific vulnerability for the effect of exposures on brain health that would indicate optimal time-windows for prevention.

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