Abstract: The invention provides compositions and methods for treating, preventing, delaying the onset, and/or delaying the development of a disease or condition for which the activation, differentiation, and/or proliferation of one or more cell types is beneficial. These compositions and methods include, for example, a hydrogenated pyrido[4,3-b]indole such as dimebon and/or a cell that has been incubated with a hydrogenated pyrido[4,3-b]indole such as dimebon. In some embodiments, the compositions and methods also include a growth factor and/or an anti-cell death compound. The invention also provides methods of activating a cell, promoting the differentiation of a cell, and/or promoting the proliferation of a cell by incubating the cell with one or more hydrogenated pyrido[4,3-b]indoles or pharmaceutically acceptable salts thereof. In some embodiments, the cell is also incubated with one or more growth factors and/or anti-cell death compounds.

Abstract: The invention provides methods and combination therapies for treating and/or preventing and/or slowing the onset and/or development of Alzheimer's disease using a hydrogenated pyrido (4,3-b) indole (e.g., dimebon) in conjunction with another compound, pharmaceutically acceptable salt thereof or therapy for Alzheimer's disease.