Reacción a "Reactions: use of erectile dysfunction drugs associated with reduced risk of Alzheimer's in men "

The role of nitric oxide neurotransmission in the consolidation, encoding and retrieval of memory has been known for a few years. Nitric oxide is both involved peripherally on erectile function (by mediating vasodilation) and centrally in cognition, by modulating neuronal function. For example, nitric oxide dependent transmission has been observed as needed for perirhinal cortex-dependent visual recognition memory (Tamagnini et al., 2013). 

In theory it is possible that promoting nitrergic transmission could improve memory function, but the question remains whether the observed association is describing a direct effect. This is a great study but more hard evidence is needed to test a mechanism of action. It could be that it exerts a therapeutic effect directly affecting neurons (if the drug is able to cross the blood brain barrier) and/or by increasing blood flow but both these hypotheses need to be tested.