Early Detection of Alzheimer's Disease Using MRI and Machine Learning: An Interdisciplinary Exploration of Neuroimaging and AI

This article introduces the educational neuroscience project Early-Alzheimers-MRI-Detection released by Shreya Shankar (M.Sc. Zoology, research interests include neuroscience, medical AI, etc.) on GitHub in July 2026. The project systematically explores how to use Magnetic Resonance Imaging (MRI) and machine learning technologies for early detection of Alzheimer's Disease (AD), covering the complete process from brain anatomy, pathological mechanisms, image preprocessing to machine learning. It aims to provide learners with an interdisciplinary knowledge framework to support early intervention and improve the prognosis of AD patients.

AD is the main neurodegenerative disease causing dementia in the elderly, affecting approximately 55 million people worldwide, and is expected to triple by 2050. Clinical diagnosis is mostly in the middle to late stages, missing the optimal intervention window. Early detection is key—pathological changes in the brain occur years before symptoms appear. As a non-invasive imaging method, MRI can capture early structural changes. This project integrates neuroscience, neuroimaging, and AI to provide a complete knowledge framework from theory to practice.

Healthy Brain Structures: Key regions related to AD include the hippocampus (core of memory, the first to atrophy in AD), cerebral cortex (higher cognition, specific areas thin), and ventricular system (compensatory enlargement after brain tissue atrophy).

Pathological Mechanisms: The two major markers are β-amyloid plaques (accumulate between neurons, interfere with signals) and neurofibrillary tangles (hyperphosphorylation of tau protein leading to cell death). Pathological changes first appear in the medial temporal lobe and then spread to other cortical regions.

MRI uses strong magnetic fields and radiofrequency pulses to generate high-resolution anatomical images, with no ionizing radiation and better soft tissue contrast than CT. Key MRI biomarkers for early AD detection: 1. Hippocampal atrophy (most sensitive and specific, related to the risk of MCI progression); 2. Cortical thinning (entorhinal cortex, temporoparietal regions, etc., related to cognitive decline); 3. Ventricular enlargement (compensatory for brain tissue atrophy, auxiliary indicator).

Public Datasets: ADNI (largest scale, multimodal data covering normal aging to AD), OASIS (includes cross-sectional and longitudinal data; OASIS-3 adds PET and cognitive data).

Preprocessing Steps: Skull stripping (retain brain parenchyma) → Spatial normalization (registration to standard space) → Intensity normalization (eliminate signal differences) → Bias field correction (correct magnetic field inhomogeneity) → Segmentation (gray matter/white matter/cerebrospinal fluid).

ML Workflow: Feature extraction (volume, shape, texture, deep learning features) → Feature selection/dimensionality reduction (avoid overfitting) → Model training (logistic regression, SVM, random forest, CNN, etc.) → Cross-validation (evaluate generalization ability).

Evaluation Metrics: Accuracy (proportion of correct classifications), Sensitivity (low missed diagnosis rate), Specificity (reduce unnecessary examinations), ROC-AUC (comprehensive discriminative ability), F1 score (more effective in case of class imbalance).

Limitations: Data heterogeneity (different device parameters affect generalization), insufficient sample diversity (mainly Western populations), disease heterogeneity (many subtypes), poor model interpretability (deep learning black box).

Future Directions: Multimodal fusion (combining PET, cerebrospinal fluid, genetic information), longitudinal analysis (predict progression), federated learning (multi-center data integration under privacy protection), explainable AI (provide basis for clinical decision-making).

This project is an excellent resource for medical AI beginners, systematically organizing the knowledge chain from neuroscience basics to ML applications. Early AD detection carries the hope of improving patients' quality of life. With technological progress and method innovation, it is expected to identify disease traces before memory decline in the future, buying time for intervention.