New Delhi: Brains of people with dementia, alcohol addiction, or psychiatric disorders such as schizophrenia might show an increased ageing, with each condition leaving its own patterns in specific areas of the brain, a study has shown.
Scientists calculate how old the brain is relative to the body using ‘predictive age difference‘ — difference between chronological age and age predicted by brain imaging — with a positive value indicating that ageing has increased.
Researchers, including those from Nanjing University of Aeronautics and Astronautics, China, collected structure magnetic resonance imaging (MRI) data from 45,900 healthy people across several brain imaging banks, and compared them with of 2,698 patients with different brain conditions and differences.
The conditions analysed included attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), alcohol or tobacco addiction, Alzheimer’s disease, mild cognitive impairment, schizophrenia, bipolar disorder and major depressive disorder.
The authors found that neurodegenerative disorders — Alzheimer’s disease and mild cognitive impairment — had the largest association with a high predictive age difference.
Addiction and psychiatric disorders were also associated with an increased predictive age difference (PAD), whereas brains of people with ADHD or ASD and healthy participants showed no differences in PAD values.
“Results showed that while PAD was consistently greater across disorders, different brain disorders showed different degrees of abnormality, the highest effects in dementia, followed by addiction and psychiatric disorders, but not different from expected in developmental disorders,” the authors wrote.
They also looked at PAD values in specific areas of the brain, and examined which genes showed an increased expression in people with different brain conditions.
The prefrontal cortex — responsible for higher level functions such as attention and decision-making — showed a higher PAD across brain disorders.
A higher predictive age difference in the frontal and temporal lobes — involved in executive function, voluntary movement and language comprehension — was associated with psychiatric disorders, while a high value in the frontal and occipital cortex (visual processing) was associated with dementia.
Addiction was connected with a high PAD in the default mode network, which is involved when one is thinking idly, among other brain regions.
While the results are correlational, and not causal, and while some conditions such as psychiatric disorders and addiction have high co-occurrence, the authors suggest that understanding more about predictive age difference could help provide biomarkers for commonly occurring brain disorders.
They added, “Different neurological disorders appear to leave different signatures on the brain aging clock, which may help researchers better understand the neural and biological pathways involved in these conditions.”
