A Review of Alzheimer’s Pathophysiology, Diagnostic Methods, and Multimodal Techniques

Alzheimer's disease (AD) is a neurologic condition that is categorized by a progressive loss of neurons with time. It is a particularly frequent kind of dementia and mostly impacts cognitive and motor functions. It’s prevalent in the elderly population, but the onset occurs at an incredibly early age. Early identification of AD is crucial for the successful management of the condition and for the development of novel treatments that can halt or reverse it. Because clinical symptoms may appear after substantial pathological changes have occurred, early diagnosis remains challenging despite major advances in imaging and fluid biomarkers. The situation is made worse by the expensive diagnostic techniques that are time-consuming and that cannot detect AD at an early stage. There is a better chance for potential treatments to work in the preliminary stages as no significant neuronal damage has occurred in its initial stages, which is why early detection is critical. There are many screening techniques, but they do not yet have the necessary sensitivity and specificity to correctly diagnose the condition. One approach to improve the diagnostic method for early AD detection is based on combining two or more diagnostic methods. The multi-modal approach is more effective in detecting AD early in its progression as well as differentiating it from other neurological conditions. This approach also allows for the accurate classification of patients into various stages of the disease. This review covers two topics: Alzheimer's neuropathology hypotheses and diagnostic methods. It gives an overview of different hypotheses including amyloid, tau, inflammation, oxidative stress, and mitochondrial dysfunction. The review also examines various diagnostic methods such as gait and speech analysis, and multi-modal approaches.