Almost 49,000 brain scans revealed signs of aging

To assess the rate of brain aging, the researchers used the difference between the predicted brain age and the actual age, known as the predictive age difference (PAD). A positive PAD indicates that the brain is aging faster than the body. The higher the PAD, the more pronounced the accelerated aging is.

The analysis included data from 45,900 control participants from several neuroimaging banks and 2,698 patients with various conditions, including attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASD), alcohol and tobacco addiction, Alzheimer’s disease, mild cognitive impairment, schizophrenia, bipolar disorder, and major depressive disorder.

The strongest acceleration of brain aging was associated with neurodegenerative conditions, and patients with Alzheimer’s disease and mild cognitive impairment had the highest PAD scores. Increased PAD was also observed in individuals with addictions and mental disorders. However, individuals with ADHD and ASD did not show significant differences in PAD compared to the control group.

It is important to note that the accelerated aging was not uniform but rather localized to specific regions of the brain, indicating that each condition had its own pattern of changes. For example, increased PAD in the frontal and temporal lobes was more often associated with psychiatric disorders, while increased PAD in the frontal and occipital cortices was more often associated with dementia. In cases of addiction, accelerated aging was observed in the passive brain network, the significance network, as well as in the putamen and thalamus. The increase in PAD in the prefrontal cortex was particularly noticeable, as this area showed accelerated aging in various disorders.

In addition to visualization, the experts compared the data with the characteristics of gene expression: different conditions had their own profiles of gene activity. Although the results are correlational rather than causal, and the conditions themselves often coexist (for example, addictions and mental disorders), the researchers believe that PAD analysis can serve as a basis for finding biomarkers of common brain diseases.

According to the authors, different neurological disorders leave different imprints on the brain’s aging clock. This can help us better understand the neural and biological mechanisms underlying these conditions, and in the long run, identify risks earlier and tailor treatment approaches more accurately.