We appreciate the interest from Lu et al. suggesting a possible influence on dementia risk owing to the use of aluminum-containing drugs for acid-related disorders among users of proton pump inhibitors (PPIs).1, 2

The association between exposure to aluminum and dementia risk is important to investigate where, as also pointed out by Lu et al., evidence is inconclusive to date.3 However, whether this biases the reported association in our study between PPI users and dementia risk is unlikely.

Experimental studies have revealed various neurotoxic effects attributed to aluminum exposure.4 Although the use of aluminum is widespread in food production, drinking water purification, medications, and vaccines, the absorption of aluminum in humans is typically low and renal elimination is efficient.5, 6 While the association between aluminum exposure and dementia risk has been a subject for research and discussion for a century, the question remains unresolved.3, 7 

Since aluminum-containing antacids do not require a prescription, individual-level data on the use of these drugs were not available in our nationwide registry-based study.