Curiosity got the better of me and I purchased the article.
While I can't legally post it here, I can answer any questions you all might have.
Here are the highlights:
1. The patient was a 68-year-old man with mild AD (beyond mild cognitive impairment, but still quite functional).
2. The 40% memory improvement was on this test. Based on the description, it sounds similar to various brain games I've played. I don't think a 40% improvement in raw score is possible for most people, but this patient managed exactly that. Impressive.
3. Although the authors acknowledged that the use of bexarotene in AD started with rat studies showing a reduction in cerebral amyloid, those studies could not be reproduced. Indeed, the patient's PET scan showed worse metabolism (1.94) at the end of the 6-month 300 mg/d dosing regimen than at the beginning (2.08). They did measure amyloid, tau, and phosphotau in the CSF, but the relationship to their cerebral counterparts is unclear. In any event, plaque reduction does not seem to have caused the memory improvement.
4. The authors suspect enhanced neuronal cholesterol efflux as the reason for the memory improvement. This goes back to the ancient hypothesis that AD is a lysosome storage disorder. Evidently, in addition to accreting plaque, sufferers accumulate excessive amounts of cholesterol inside neurons, impeding their function. This is aggravated by positive APEO4 gene status, which is involved in cholesterol transport; the patient had a single copy (of a maximum 2). Indeed, during the study, the patient's LDL rose as high as 175. Otherwise, no side effects were recorded. Extra olive oil consumption would be well advised until cholesterol levels return to baseline; in my view, that would indicate the attainment of maximum effect.
5. Family and relatives observed improvements in daily living, but not a normalization of memory function. Unfortunately, there is no report as to the degree to which his family thought that memory had improved, despite not having normalized. Perhaps earlier intervention could have accomplished that.