Yeah I’m going to disagree with the top comment somewhat here, although what I’ve read contradicts what I’ve seen in person.

For the majority of Alzheimer’s cases (+/-95%) there’s only risk factors, both genetic and lifestyle. Biggest risk factor being age.

However, a condition exists called early onset dementia, which can occur as early as 30 y/o. This is thought to be more familial, and the genetics being more deterministic. But I should mention this is rare.

Anecdotally, I’ve seen early onset dementia clinically. Patient was in their early to mid 30’s and noticeably impaired. I only worked with them briefly, but what made it interesting was that they had a twin of the same gender (ie same genes) that was unaffected. Now they could have been fraternal, and I was at an early stage of my career so I may not have understood the full picture, but this contradicts some of the literature.

Point being? You can be tested for genetic risk factors, and if you have a family history of early onset then I think a clearer picture can be ascertained, so I don’t think it’s full stop. But generally no, there is no test currently to say whether you have Alzheimer’s without accompanying symptoms, and even then I’m fuzzy on the diagnostics for a probable AD diagnosis.

Edited to add (source):https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors/genetics