This is what ClaudeAI summarised (so not sure how accurate):

Several studies have investigated a possible link between long term proton pump inhibitor (PPI) use and dementia or cognitive decline. The findings are mixed, but concerning enough to warrant caution with prolonged use of PPIs, especially in the elderly.

Some of the key studies include:

• A 2016 German study of over 73,000 people found long term PPI use (>1 year) was associated with a 44% increased risk of dementia. More frequent or longer-acting PPIs and higher doses were linked to greater risk. (Gomm W, et al. JAMA Neurol 2016)

• A 2017 US study followed over 10,000 participants and found those on PPIs for 18 months or more had a 25-50% higher risk of impaired cognitive functioning based on memory and verbal fluency tests. (Klatte DCF, et al. J Am Geriatr Soc 2017)

• However, several other studies found no conclusive evidence to link PPIs and dementia. A 2017 meta-analysis of 16 studies with over 200,000 participants concluded there were small statistical effects observed in some studies, but too much uncertainty and inconsistency to definitively determine a causal relationship. Larger, longitudinal studies were recommended. (Bian Y, et al. Front Aging Neurosci 2017)

• Possible mechanisms theorized include changes in vitamin and mineral absorption (e.g. B12, magnesium), increased susceptibility to infections, small intestinal bacterial overgrowth leading to increased inflammatory cytokines, and direct neurochemical effects in the brain. But more research is needed.

While no smoking gun has yet been found, clinicians generally recommend the following based on these concerning but inconclusive findings:

  1. Only prescribe PPIs when clearly medically indicated based on severity of symptoms and risks versus benefits. Lifestyle and alternative medication options should be tried first before PPIs when possible.

  2. Use the lowest effective dose for the shortest necessary duration. Try gradually reducing or discontinuing PPIs under medical guidance when symptoms are stable.

  3. All patients on long term PPIs, especially the elderly, should be monitored closely for side effects as well as cognitive or functional decline. Report any changes to the prescribing clinician right away.

  4. Patients on PPIs long term should maintain a healthy diet, exercise, stay socially active, and take supplements as directed to support brain and general health. Lifestyle factors may help lower risks associated with PPI use.

  5. Educate patients about the uncertainties around long term PPI use and possible links to dementia/cognitive impairment. Shared and informed decision making around the risks versus benefits of continuing or reducing PPI therapy long term is key, based on individual patient priorities and medical needs.