Brain age prediction from MRI scans in neurodegenerative diseases

Abstract

Purpose of review: This review explores the use of brain age estimation from MRI scans as a biomarker of brain health. With disorders like Alzheimer's and Parkinson's increasing globally, there is an urgent need for early detection tools that can identify at-risk individuals before cognitive symptoms emerge. Brain age offers a noninvasive, quantitative measure of neurobiological ageing, with applications in early diagnosis, disease monitoring, and personalized medicine.

Recent findings: Studies show that individuals with Alzheimer's, mild cognitive impairment (MCI), and Parkinson's have older brain ages than their chronological age. Longitudinal research indicates that brain-predicted age difference (brain-PAD) rises with disease progression and often precedes cognitive decline. Advances in deep learning and multimodal imaging have improved the accuracy and interpretability of brain age predictions. Moreover, socioeconomic disparities and environmental factors significantly affect brain aging, highlighting the need for inclusive models.

Summary: Brain age estimation is a promising biomarker for identify future risk of neurodegenerative disease, monitoring progression, and helping prognosis. Challenges like implementation of standardization, demographic biases, and interpretability remain. Future research should integrate brain age with biomarkers and multimodal imaging to enhance early diagnosis and intervention strategies.

Keywords: MRI; brain age; cognitive decline; machine learning; neurodegenerative diseases.

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FIGURE 1

A high-level overview of a Brain Age prediction pipeline. Firstly, an MRI scan of an individual's brain is acquired. Next, the scan is input into a machine-learning model, previously trained on a large number of brain scan from healthy people and their age labels, and outputs the predicted age of the individual, the so-called ‘brain age’. The brain age is then compared to the chronological age of the individual; if the brain age is lower or equal to the chronological age, then the individual is healthy (attributed to high level of education, regular exercise, healthy diet and more). If the brain age is higher than the chronological age, then the individual is likely to have poorer brain health than expected for their age, potentially due to a disease process (for example, Alzheimer's disease, Parkinson's disease, frontotemporal dementia or another neurodegenerative disease).