HSGO: Harmonized Swarm Learning With Guided Optimization for Multi-Center sMRI Classification of Alzheimer's Disease

Developing robust Alzheimer's Disease (AD) classification models necessitates extensive training data, but aggregating multi-center medical data poses privacy risks. Although Federated Learning (FL) and Swarm Learning (SL) allow training generic models without data sharing, their performance is limited by variations in AD pathology features and sample class imbalances across centers. To address this issue, we propose a novel Harmonized Swarm Learning framework with Guided Optimization (HSGO) to enhance multi-center collaboration while preserving data privacy. Our framework employs a class-balanced loss function to train a robust generic model and guides the optimization of personalized models towards the generic model, eliminating extra AD pathology feature extraction steps. Furthermore, we design a dynamic feature similarity storage mechanism to facilitate personalized training. Experiments performed under two different multi-center data partitioning scenarios demonstrate that HSGO achieves competitive performance when compared with five baseline methods. Additionally, Layer-wise Relevance Propagation (LRP) analysis indicates that HSGO may help identify potential key brain regions in AD by integrating local and global features compared to traditional SL.