Structural, functional and molecular imaging in dementia and Alzheimer's disease: A review of multimodal approaches

Imaging in Dementia and Alzheimer's Disease

Abstract

Dementia, particularly Alzheimer’s disease (AD), presents a growing global health challenge. Early and accurate diagnosis is critical for timely intervention and effective care planning. Multimodal neuroimaging—which integrates structural, functional, and molecular techniques—has emerged as a powerful tool to improve diagnostic precision and subtype differentiation.

This review synthesizes findings from the past two decades, focusing on key imaging modalities including magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and functional MRI (fMRI). Structural MRI identifies atrophy patterns, while PET provides metabolic and molecular insights through FDG, amyloid, and tau tracers. Functional techniques like resting-state fMRI and SPECT add information on neural connectivity and perfusion. Advanced methods such as neurite orientation dispersion and density imaging (NODDI) and hybrid PET/MRI systems further enhance diagnostic utility.

Multimodal approaches demonstrate superior accuracy in detecting early disease and distinguishing AD from non-Alzheimer dementias. However, challenges remain, including high costs, limited access, protocol variability, and ethical concerns in asymptomatic populations. Emerging innovations in artificial intelligence and blood-based biomarkers may improve scalability and accessibility.

Multimodal imaging represents a critical step toward precision diagnostics in dementia, with implications for clinical practice, research, and policy.