Dementia addiction and psychiatric disorders show distinct patterns of accelerated brain aging

People with dementia, mild cognitive impairment, alcohol addiction, or psychiatric disorders such as schizophrenia show increased brain aging, each in specific patterns within the brain, according to a study published July 21^st in the open access journal PLOS Medicine by Shile Qi from the Nanjing University of Aeronautics and Astronautics, China, and colleagues.

Some conditions can make the brain age faster. Scientists calculate how old the brain is relative to the body using the predictive age difference (PAD), the difference between chronological age and the age predicted by brain imagine, where a positive PAD indicates that aging is accentuated or increased. To better understand how brain disorders and divergences might affect brain aging, the authors of this study collected structure magnetic resonance imaging (MRI) data from 45,900 controls across several brain imaging banks, and compared them with of 2,698 patients with different brain conditions and differences, including attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), alcohol or tobacco addiction, Alzheimer’s disease (AD), mild cognitive impairment (MCI), schizophrenia, bipolar disorder or major depressive disorder.

The authors found that neurodegenerative disorders of AD and MCI had the largest association with a high PAD. Addiction and psychiatric disorders were also associated with increased PAD. In contrast, there were no differences in PAD between people with ADHD or ASD and controls.

The researchers also looked at PAD values in specific areas of the brain, and examined which genes showed increased expression in people with different brain conditions. The prefrontal cortex showed higher PAD across brain disorders. Higher PAD in the frontal and temporal lobes was associated with psychiatric disorders, while high PAD in the frontal and occipital cortex was associated with dementia. Addiction was connected with high PAD in the default mode network, and in the salience network and the putamen and thalamus. There were also differences in gene transcription that associated with specific conditions and divergences. While the results are correlational, and not causal, and while some conditions such as psychiatric disorders and addiction have high co-occurrence, the author suggest that understanding more about PAD could help provide biomarkers for commonly occurring brain disorders.

The authors add, “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.”