Shingles vaccine, sildenafil and riluzole emerge as top repurposing candidates for Alzheimer’s
Mar 4th 2026
A Delphi consensus by international experts narrowed 80 nominated drugs to three repurposing priorities for Alzheimer’s disease — the shingles vaccine, sildenafil and riluzole — citing mechanistic rationale, nonclinical efficacy and acceptable safety and urging pragmatic trials to evaluate clinical benefit.
- An international Delphi panel considered 80 nominated drugs, reviewed seven to eight candidates, and reached consensus on three high-priority repurposing targets for Alzheimer’s disease.
- The three shortlisted candidates are the live attenuated herpes zoster vaccine (Zostavax), the phosphodiesterase 5 inhibitor sildenafil, and the glutamate modulator riluzole.
- Selection was based on mechanistic plausibility, consistent nonclinical efficacy, tolerability in older people, and existing safety data that enable faster trial entry.
- Epidemiological studies and a systematic review associate zoster vaccination with a reduced risk of incident dementia, with pooled estimates around a 16 to 20 percent relative reduction in some cohorts.
- Sildenafil and riluzole show reproducible cognitive and pathological benefits in animal models but have limited and mixed clinical or epidemiological evidence in people with Alzheimer’s.
- The stakeholder lay panel ranked the herpes zoster vaccine highest because of simple dosing and established safety, and the authors recommend pragmatic remote or hybrid clinical trials using platforms such as PROTECT to test these candidates.