Aging beyond diagnosis: the MRI brain age gap across disorders

Area of Science:

• Neuroscience
• Radiology
• Psychiatry

Background:

• The brain age gap (BAG), the difference between predicted brain age and chronological age, is a potential biomarker for neurobiological aging.
• Its significance across different neurological and psychiatric disorders remains unclear.

Purpose of the Study:

• To meta-analytically evaluate the transdiagnostic significance of BAG across Alzheimer's disease (AD), mild cognitive impairment (MCI), multiple sclerosis (MS), Parkinson's disease (PD), schizophrenia (SCZ), stroke, and bipolar disorder (BD).
• To identify shared and disorder-specific patterns of accelerated brain aging.

Main Methods:

• A meta-analysis of 65 MRI-based studies was conducted.
• Standardized mean differences (Hedges' g) were computed for BAG between patient and control groups.
• Random-effects models, subgroup analyses, and meta-regressions were employed to assess BAG patterns and influences.

Main Results:

• Significantly elevated BAG was observed across all included disorders.
• The largest effect sizes for accelerated brain aging were found in MS and AD.
• Moderate BAG elevations were noted in SCZ and MCI, with smaller but significant acceleration in PD. Stroke and BD showed preliminary evidence of elevated BAG.

Conclusions:

• The brain age gap serves as a transdiagnostic indicator of apparent accelerated brain aging in AD, MCI, MS, PD, and SCZ.
• The magnitude of BAG differs substantially across disorders, and high heterogeneity necessitates cautious interpretation of pooled effect sizes.
• Further research on stroke and BD is warranted due to limited study numbers.