Abstract: Compositions of dendrimers conjugated with one or more therapeutic agents that decrease exosome secretion and methods of use thereof for treating, alleviating, and/or preventing one or more symptoms associated with one or more neurological disease or disorders, cancer, inflammatory diseases, bacterial and viral infections, and other disorders have been developed. Preferably, the therapeutic agents are one or more agents that inhibit or reduce activity and/or quantity of neutral sphingomyelinase 2 (nSMase2) such as small molecule inhibitors of nSMase2. Compositions are particularly suited for reducing A? plaque formation, reducing tau propagation, improving cognition, or combinations thereof in a subject with psychiatric and neurological disorders. Compositions are also suited for treating, alleviating, and/or preventing one or more symptoms associated with cancer, bacterial and viral infections, and inflammatory diseases.