Multiple Subtypes of Alzheimer's Disease Base on Brain Atrophy Pattern

Area of Science:

• Neuroscience
• Neurology
• Biomedical Imaging

Background:

• Alzheimer's disease (AD) is a complex neurodegenerative disorder with heterogeneous clinical presentations.
• Understanding AD subtypes is crucial for disentangling disease mechanisms and improving patient outcomes.

Purpose of the Study:

• To identify and characterize distinct subtypes of Alzheimer's disease based on brain structural patterns.
• To analyze the neuropsychological and neuropathological features of each identified AD subtype.

Main Methods:

• Utilized the Mixture of Experts (MOE) method on cortical thickness data from 192 AD and 228 cognitively normal (CN) subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database.
• Applied piecewise linear classifiers to differentiate AD subtypes from CN individuals.
• Analyzed atrophy patterns, cognitive performance, and neuropathological markers.

Main Results:

• Identified four distinct AD subtypes: Occipital Sparing AD Subtype (OSAD, 29.2%), Left Temporal Dominant Atrophy AD Subtype (LTAD, 22.4%), Minimal Atrophy AD Subtype (MAD, 16.1%), and Diffuse Atrophy AD Subtype (DAD, 32.3%).
• Observed unique atrophy patterns, cognitive profiles, and neuropathological characteristics for each subtype.
• Noted asymmetrical atrophy in the left lateral temporal-parietal cortex in some AD subjects, the worst cerebrospinal fluid levels in OSAD, and the highest APOE ε4/ε2 proportions in MAD.

Conclusions:

• The study successfully delineated four distinct AD subtypes with specific clinical and biological signatures.
• These findings provide a foundation for more individualized diagnosis, prognosis, and potentially targeted therapeutic strategies for Alzheimer's disease.
• The characterized subtypes offer valuable insights into the heterogeneity of AD, facilitating better clinical management.