This paper In the Journal of Alzheimer's Disease describes other AD genetic risks that arise from genes that regulate proteins involved in cholesterol metabolism, amyloid processing and clearance, immune response, and nerve cell protective factors:
J Alzheimers Dis. 2018;62(2):887-900.
A Network of Genetic Effects on Non-Demented Cognitive Aging: Alzheimer's Genetic Risk (CLU + CR1 + PICALM) Intensifies Cognitive Aging Genetic Risk (COMT + BDNF) Selectively for APOEɛ4 Carriers.
In this study, the researchers created three groups of risk genes and analyzed the increased or decreased risk for decline in Executive Function according to the risks conferred by each of gene groups. APOE was one group, and is well known to have the greatest impact on cognitive decline and disease risk. The others were CLU/CR1/PICALM (grouped together as one risk factor) and COMT/BDNF (grouped together as one risk factor). They evaluated degradation of executive function in normal aging based on how many genetic risk factors were in play in addition to APOE4. I have APOE4, the gene conferring the highest risk for cognitive decline and AD (group 1). have an even higher risk of cognitive decline and AD due to my snps for CLU and CR1 and somewhat for PICALM (so for this group I am at high risk if not the highest). I have a lower risk due to snps for COMT and BDNF (Whew!).
There are other studies that evaluate even more genes, but many of those are not useful yet to many of us, because the genes they analyzed are not specified by the genetic data obtained through 23andMe.
E3/E4, but still optimistic