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We celebrate our birthdays, but what about our brain’s birthday? Our brain clock is always ticking. Brain age refers to the gap between our brain’s age and our actual age. Researchers measure brain age by observing functional changes that occur as we grow old, which offers insight into our brain health over time.
An international team of researchers investigated the effect of our environment on brain age. They examined data from 5,306 participants in 2 different geographical groups: Latin American and Caribbean (LAC) countries and Non-LAC countries. The first set of 2953 participants came from 7 different LAC countries, including Mexico, Cuba, Columbia, Peru, Brazil, Chile, and Argentina. The other 2,353 participants came from 8 different non-LAC countries, including China, Japan, USA, Italy, Greece, Turkey, UK, and Ireland.
They categorized the participants into 4 additional groups: healthy people or the control group, people with mild cognitive impairment, people with Alzheimer’s disease, and people with behavioral variant frontotemporal dementia. Dividing participants based on their neurocognitive health allowed the researchers to compare brain age discrepancies between these groups.
To evaluate how environmental differences affect brain aging, the researchers tracked blood flow in the patients’ brains using functional magnetic resonance imaging and measured electrical activity in their brains using electroencephalography. They collected these data while the study participants thought a certain way or performed a particular task. The researchers also developed a deep learning model to recognize patterns in the large datasets they produced. In general, the researchers found that LAC participants had older brain ages compared to non-LAC participants. They saw this aging primarily in the frontal posterior networks of the brain, which are related to memory and goal-driven tasks and behaviors.
The team proposed that multiple socioeconomic factors, referred to as predictors, explained the older brain ages of LAC participants. They evaluated the influence of each predictor using a machine learning approach known as a gradient-boosting regression model, which combines many smaller models to make a more accurate prediction.
They also used various other statistical strategies including one called permutation importance. In this strategy, predictor values are randomly shuffled and researchers measured how the shuffling changed the model’s prediction error. If the prediction error increased significantly when a particular predictor value was shuffled, the predictor was deemed influential. They found the most influential predictors for this group included their neurocognitive disorders followed by socioeconomic inequality, increased air pollution, healthcare scarcity, high disease burden, and low education levels.
The researchers also observed larger brain age gaps in LAC females with a neurocognitive disorder than in their male counterparts. The researchers determined that this was because LAC countries experience higher levels of gender inequality. A greater brain age gap compared to their respective male counterparts was specifically noted for the LAC female group suffering from Alzheimer’s disease, but healthy LAC females also showed a larger brain age gap than males.
While the non-LAC group tended to have younger brain ages than the LAC group, they found participants from this geographical group were similarly affected by the impact of neurocognitive diseases. They saw this trend in the brain age gap between non-LAC people with mild cognitive impairment and non-LAC people with Alzheimer’s disease. The healthy non-LAC group had the lowest brain age gap, people with mild cognitive impairment had a higher brain age gap, and people with Alzheimer’s had the highest brain age gap.
The researchers concluded their results highlight the impact of health-related, environmental, and societal factors on brain aging. They suggested that their findings emphasize the need for targeted interventions to mitigate brain aging, especially in vulnerable socioeconomic populations.
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Study Information
Original study: Brain clocks capture diversity and disparities in aging and dementia across geographically diverse populations
Study was published on: August 26, 2024
Study author(s): Sebastian Moguilner, Sandra Baez, Hernan Hernandez, Joaquín Migeot, Agustina Legaz, Raul Gonzalez-Gomez, Francesca R. Farina, Pavel Prado, Jhosmary Cuadros, Enzo Tagliazucchi, Florencia Altschuler, Marcelo Adrián Maito, María E. Godoy, Josephine Cruzat, Pedro A. Valdes-Sosa, Francisco Lopera, John Fredy Ochoa-Gómez, Alfredis Gonzalez Hernandez, Jasmin Bonilla-Santos, Rodrigo A. Gonzalez-Montealegre, Renato Anghinah, Luís E. d’Almeida Manfrinati, Sol Fittipaldi, Vicente Medel, Daniela Olivares, Görsev G. Yener, Javier Escudero, Claudio Babiloni, Robert Whelan, Bahar Güntekin, Harun Yırıkoğulları, Hernando Santamaria-Garcia, Alberto Fernández Lucas, David Huepe, Gaetano Di Caterina, Marcio Soto-Añari, Agustina Birba, Agustin Sainz-Ballesteros, Carlos Coronel-Oliveros, Amanuel Yigezu, Eduar Herrera, Daniel Abasolo, Kerry Kilborn, Nicolás Rubido, Ruaridh A. Clark, Ruben Herzog, Deniz Yerlikaya, Kun Hu, Mario A. Parra, Pablo Reyes, Adolfo M. García, Diana L. Matallana, José Alberto Avila-Funes, Andrea Slachevsky, María I. Behrens, Nilton Custodio, Juan F. Cardona, Pablo Barttfeld, Ignacio L. Brusco, Martín A. Bruno, Ana L. Sosa Ortiz, Stefanie D. Pina-Escudero, Leonel T. Takada, Elisa Resende, Katherine L. Possin, Maira Okada de Oliveira, Alejandro Lopez-Valdes, Brian Lawlor, Ian H. Robertson, Kenneth S. Kosik, Claudia Duran-Aniotz, Victor Valcour, Jennifer S. Yokoyama, Bruce Miller, Agustin Ibanez
The study was done at: Latin American Brain Health Institute, Universidad Adolfo Ibañez (Chile), Cognitive Neuroscience Center, Universidad de San Andrés (Argentina), Department of Neurology, Massachusetts General Hospital and Harvard Medical School (USA), Universidad de los Andes (Colombia), Global Brain Health Institute, University of California, San Francisco (USA), Global Brain Health Institute, Trinity College Dublin (Ireland), University of California Santa Barbara (USA), Escuela de Fonoaudiología, Universidad San Sebastián (Chile), Grupo de Bioingeniería, Universidad Nacional Experimental del Táchira (Venezuela), Advanced Center for Electrical and Electronic Engineering, Universidad Técnica Federico Santa María (Chile), University of Buenos Aires (Argentina), Chengdu Brain Sciences Institute, University of Electronic Sciences and Technology of China (China), Cuban Neuroscience Center (Cuba), Grupo de Neurociencias de Antioquia, University of Antioquia (Colombia), Universidad Surcolombiana Neiva (Colombia), Universidad Cooperativa de Colombia (Colombia), Neurocognition and Psychophysiology Laboratory, Universidad Surcolombiana (Colombia), University of São Paulo (Brazil), Traumatic Brain Injury Cognitive Rehabilitation Out-Patient Center, University of São Paulo (Brazil), Center for Social and Cognitive Neuroscience, Universidad Adolfo Ibáñez (Chile), University of Chile, Santiago (Chile), Centro de Neuropsicología Clínica (Chile), Faculty of Medicine, Izmir University of Economics (Turkey), Brain Dynamics Multidisciplinary Research Center, Dokuz Eylül University (Turkey), Izmir Biomedicine and Genome Center (Turkey), University of Edinburgh (UK), Sapienza University of Rome (Italy), Hospital San Raffaele Cassino (Italy), Trinity College Dublin (Ireland), Istanbul Medipol University (Turkey), Pontificia Universidad Javeriana (Colombia), Hospital Universitario San Ignacio (Colombia), Universidad Complutense de Madrid (Spain), University of Strathclyde (UK), Universidad Católica San Pablo (Perú), Universidad de Valparaíso (Chile), Universidad ICESI (Colombia), University of Surrey (UK), University of Glasgow (UK), University of Aberdeen (UK), Sorbonne Université, Paris Brain Institute (France), Harvard Medical School (USA), Clínica Alemana-Universidad Desarrollo (Chile), Universidad de Chile, Centro de Investigación Clínica Avanzada (Chile), Universidad del Valle (Colombia), Instituto Peruano de Neurociencias (Perú), Instituto Nacional de Neurología y Neurocirugía MVS, Universidad Nacional Autónoma de México (Mexico)
The study was funded by: Latin American Brain Health Institute, National Institute of Health, Fogarty International Center, National Institute of Aging, Alzheimer’s Association, Rainwater Charitable Foundation, The Bluefield Project to cure frontotemporal dementia, Global Brain Health Institute
Raw data availability: Available at OSF Home
Featured image credit: From Freepik
This summary was edited by: Andrea Corpolongo
