A recently developed AI-based ‘brain clock’ can now reveal whether a person’s brain is aging faster than expected based on their chronological age. The findings suggest that brain aging is influenced by factors beyond mere years, including socioeconomic status, environmental pollution, and regional inequalities.
According to Agustín Ibáñez, the lead author of the study and a neuroscientist at Adolfo Ibáñez University in Santiago, “The way your brain ages is influenced by where you live, your lifestyle, your socioeconomic level, and the environmental pollution you are exposed to. Countries aiming to improve brain health must address these structural inequalities.”
The study, published on August 26 in Nature Medicine, has been lauded by experts for its innovative approach. Vladimir Hachinski, a neuroscientist at Western University in London, Canada, described the work as “truly impressive.”
Understanding Brain Aging
The research team examined brain aging by analyzing functional connectivity, which measures how different regions of the brain interact with each other—a process that generally diminishes with age. The study included 5,306 participants from 15 countries, encompassing both healthy individuals and those with cognitive impairments such as Alzheimer’s disease.
Participants’ brain activity was monitored using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). The resulting data was fed into two deep-learning models designed to estimate brain age. By comparing the predicted brain age with the participants’ actual chronological age, researchers calculated the ‘brain-age gap.’
Key Findings: The Impact of Inequality
The results showed that individuals with Alzheimer’s or other dementias had more significant brain-age gaps compared to those with mild cognitive impairment or healthy individuals. Notably, participants from Latin America and the Caribbean exhibited larger brain-age gaps on average, correlating with the region’s high levels of socioeconomic inequality.
Ibáñez emphasized that structural socioeconomic disparities, exposure to pollution, and health inequities were strongly linked to accelerated brain aging, especially in Latin American populations. The study also revealed that women living in countries with high gender inequality, particularly in Latin America and the Caribbean, had larger brain-age gaps than men.
Challenges and Future Directions
The diversity of the study’s sample, spanning multiple continents, is a remarkable achievement, according to Hachinski. However, he cautioned that functional connectivity is just one aspect of brain health and may not capture other factors like mental health conditions, including depression or anxiety.
One potential limitation of the study was the variation in fMRI and EEG equipment quality across the 15 countries involved. Lower-income nations might have used older, less advanced machines, potentially affecting data quality. However, Ibáñez’s team found no direct link between data quality and brain-age gaps or structural inequality.
Looking ahead, Ibáñez’s team plans to investigate the relationship between brain-age gaps and national income by comparing data from Asian nations and the United States. They also intend to incorporate ‘epigenetic’ clocks, which assess biological age through DNA modifications. This research could ultimately lead to personalized medicine approaches that reflect the full biological diversity of the human brain.
“We must understand this diversity,” Ibáñez stated. “A global science of dementia cannot be achieved without addressing these differences.”