Alzheimer's disease is primarily characterized by the accumulation of misfolded beta-amyloid plaques and tau protein tangles in the brain. These abnormal protein deposits disrupt neuronal function and lead to progressive cognitive decline. Unlike multiple sclerosis or epilepsy, which involve demyelination and abnormal electrical activity respectively, Alzheimer's pathology centers on protein misfolding and aggregation. Parkinson's disease also involves misfolded proteins, but principally alpha-synuclein, not the hallmark proteins seen in Alzheimer's. Thus, Alzheimer's disease uniquely features the classical buildup of specific misfolded proteins causing neurodegeneration.

Reference: Robbins Basic Pathology, Kumar, Abbas, Aster, 10th Edition.