These studies seem to confirm it:

Intermittent Fasting Protects against Alzheimer’s Disease Possible through Restoring Aquaporin-4 Polarity

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5712566/

Dietary Links to Alzheimer’s Disease
William B. Grant

https://www.researchgate.net/publication/264121252_Grant_Alzheimer_1997?_sg=uAptVfDtP2f7h2bSrf93_PVPvJMYZdcgfu-3r4Kz_u1I1al_6cC6TGxiUvRPuGr5slW4kZCx2w

Figure 1. Scatter plot of Alzheimer’s disease prevalence versus fat supply for 11 countries, along with the linear regression fit to the data (AD prevalence rate = -0.203+(0.0312*fat (grams/day))).

https://www.researchgate.net/profile/William_Grant2/publication/264121252/figure/fig1/AS:295952138162178@1447571896679/Scatter-plot-of-Alzheimers-disease-prevalence-versus-fat-supply-for-11-countries-along.png

Figure 2. Scatter plot of Alzheimer’s disease prevalence versus total food supply for 11 countries, along with the linear regression fit to the data (AD prevalence rate = -6.178 + (0.00309*(total calories/ day))).

https://www.researchgate.net/profile/William_Grant2/publication/264121252/figure/fig2/AS:295952138162179@1447571896707/Scatter-plot-of-Alzheimers-disease-prevalence-versus-total-food-supply-for-11-countries.png

Recent findings that elderly African-Americans and Japanese living in the United States have much higher prevalence of Alzheimer’s disease (6.24% and 4.1%, respectively) than those still living in their ethnic homelands (<2%) suggested that environmental rather than genetic factors are the primary agents causing Alzheimer’s disease. Recent papers linking clinical expression of Alzheimer’s disease to oxidative stress and cerebral infarct suggest that diet is a key factor in the development of Alzheimer’s disease. To test this hypothesis, regression analyses were performed on the prevalence of Alzheimer’s disease in the 65+ age population for 11 countries obtained from 18 community-wide studies versus components of the national diets. The primary findings are that fat and total caloric supply have the highest correlations with Alzheimer’s disease prevalence rates (r2 = 0.932 and 0.880, respectively). In addition, fish consumption is found to reduce the prevalence of Alzheimer’s disease in the European and North American countries. The literature suggests that fat contributes to oxidative stress and inflammation and that fish oils combat inflammation. Recent papers finding that several dietary components and supplements have been found effective in delaying the onset of Alzheimer’s disease, including antioxidants, fish, and nonsteroidal anti-inflammatory drugs are consistent with this finding.