physiological factors “could have been contributing,” said Alexis Stranahan, a professor at the Medical College of Georgia at Georgia Regents, who oversaw the study. So, to isolate the impact of the fat, the researchers simply removed most of it, surgically excising the large bands of fat that each mouse bore around its middle.
After recovery, these slenderised mice showed almost no interleukin 1 in their bloodstreams and, Algernon-like, soon were acing cognitive tests that had stumped them before surgery.
Conversely, when the scientists implanted the preserved fat pads into previously lean mice — and haven’t we all had nightmares about something like that happening to us in our sleep? — the animals almost immediately grew dimmer, performing far worse than previously on cognitive tests, although nothing else in their lives had changed.
The results convincingly implicated fat cells as the primary cause of the mice’s cognitive decline. Gathering more of the obesity-prone mice, they allowed all of them to grow heavy, but then started half on a daily 45-minute exercise session. Other mice remained sedentary.
After 12 weeks, running mice had lost fat and did much better on cognitive tests than the sedentary mice. The results suggested that, as the scientists write in the study, “treadmill training normalised hippocampal function,” even in animals born to be fat and that remained heavy.
Of course, these studies were conducted in mice, not people, whose brains may respond very differently. But the possibility that humans, too, may respond in similar ways is tantalising, Dr Stranahan said, and the takeaway from her study worth repeating. “Get out and move,” she said, even — and especially — if you carry extra weight. Talk with your doctor about a safe and tolerable exercise program, and then try to stick with that routine so that extra pounds won’t weigh too heavily on your mind.
- GRETCHEN REYNOLDS