From the article:
Using two different methods of statistical analysis, the team showed that the ADT [androgen deprivation therapy] group, compared to the control group, had significantly more Alzheimer’s diagnoses in the years following the initiation of androgen-lowering therapy. By the most sophisticated measure, members of the ADT [androgen deprivation therapy] group were about 88 percent more likely to get Alzheimer’s during the follow-up period.
The analyses also suggested a “dose-response effect.” The longer individuals underwent ADT the greater their risk of Alzheimer’s disease, they found. The longer-duration ADT patients also had more than double the Alzheimer’s risk of non-ADT controls.
[…]
How low testosterone would lead to increased Alzheimer’s risk isn’t precisely known, but there is some evidence that testosterone has a general protective effect on brain cells, so that lowering testosterone would leave the brain less able to resist the processes leading to Alzheimer’s dementia. Studies in mice and in humans also have suggested that lower testosterone levels may allow greater production of the Alzheimer’s protein amyloid beta. Moreover, low testosterone may increase Alzheimer’s risk indirectly, by promoting conditions such as diabetes and atherosclerosis that are known to predispose to Alzheimer’s.