A method of treating and/or preventing neurological conditions, comprising administering to a subject in need thereof a therapeutically effective amount of a p75 extracellular domain (p75ECD) or a functional fragment, variant, analogue or derivative thereof. Also provided is a method of diagnosing and/or prognosing Alzheimer's disease (AD) in a test subject comprising comparing the concentration of p75ECD and/or p75FL and/or the ratio of p75ECD:p75FL in a biological sample of the test subject to non-demented control subject(s).
