"High-fat diets have long been known to increase the risk for medical problems, including heart disease and stroke, but there is growing concern that diets high in fat might also increase the risk for depression and other psychiatric disorders."
All I know is that my actual blood test inflammation markers decreased dramatically when I started increasing my fat intake (and improving the quality of the fats), and that my mood, strength, & recovery time improved.
High fat may do these negative things to mice, but I'm not all that sure it's relevant to humans, given that our enormous brains are largely made up of cholesterol & fatty tissue.