To the Editor Dietary aluminum ingestion is theorized to be neurotoxic and play a causative role in the onset and progression of dementia.1-3 A recent meta-analysis showed that individuals chronically exposed to aluminum were 71% more likely to develop Alzheimer disease (odds ratio, 1.71; 95% CI, 1.35-2.18).4 Many strong antacids contain aluminum hydroxide and are often taken for years by patients with peptic ulcer disease or gastroesophageal reflux before they are prescribed proton pump inhibitors, and concurrent with their use. Gomm and colleagues5 do not correct for the use of aluminum-containing antacids when calculating the association of dementia with proton pump inhibitor use. How much of their observed association of proton pump inhibitor use with dementia is actually due to long-term ingestion of aluminum antacids, either currently or in the past?