From the article:

Preliminary findings suggest a relationship between obesity and dementia that could lead to promising prevention strategies in the future.

[…]

“Our results confirm the inverse association of increasing BMI with lower brain volumes in older adults and with younger, middle-aged adults and extends the findings to a much larger study sample,” […] “More importantly our data suggests a stronger connection between central obesity, particularly the visceral fat component of abdominal obesity, and risk of dementia and Alzheimer’s disease,” Dr. Seshadri added. The research showed the association between visceral adipose tissue and total brain volume was most robust and was also independent of BMI and insulin resistance."