Abstract: The inventions provided herein relate to methods, and compositions for increasing neuronal connectivity, neuronal survival and/or axonal growth of a population of neural cells in vitro, ex vivo or in vivo. For in vivo applications, in some embodiments, the methods and compositions described herein can be used to treat cognitive, motor and/or sensory function impairment and/or neurodegeneration in a subject or particularly a human subject {e.g., a human subject who is diagnosed as having, or having a risk, for a neurodegenerative and/or neurological condition such as Alzheimer's disease). Methods for determining a risk for a neurodegenerative condition or disorder, e.g., Alzheimer's disease, in a subject {e.g., a human subject) are also provided herein.