TRPV1 and Alzheimer disease: Numerous clinical trials have confirmed that topical application of capsaicin – a TRPV1 agonist – is effective in reducing chronic pruritus of unknown origin [274, 275], and PAC-14028, a TRPV1 antagonist, showed a trend towards improvement of pruritus in AD patients in a phase 2b clinical trial [276, 277] (Table 1).