Brain Atrophy and Binge Eating in FTDStudy participants were in their fifties and were suffering from various neurodegenerative diseases, including FTD and Alzheimer’s disease. Their spouses also were included in the study as healthy controls. Patients were evaluated with brain imaging, as well as with cognitive and language tests. Patients and their spouses lived at UCSF’s General Clinical Research Center for a week. For those of us without dementia, scientists have obtained evidence that when a greater amount and variety of food is set before us, many of us do indeed often eat more than we would otherwise. In the dementia study, 75 patients and their spouses were randomly assigned to two different all-you-care-to-eat lunch options on two different days. On one day, patients were offered as much as they wanted of seven different sandwiches. On the other day, they were offered as much as they wanted of just one type of sandwich of their choosing. A constant volume of food was kept on the tables. Almost half of the patients with FTD spontaneously reported feeling full but nonetheless continued to eat. “One of the patients ate 10 sandwiches in an hour even though he reported feeling full after only 2 sandwiches” Woolley says. “The patient knew he was full, but he did not stop eating.” In general, patients with FTD overate, and they were more likely to overeat when offered a variety. “You’re not full because your stomach is physically full,” Woolley explains. “You’re full because your brain tells you not to eat any more. The message can be turned on and off, depending on the food available. “You may eat turkey at Thanksgiving until you feel completely full, but then out comes the pumpkin pie – with some different sensory qualities – and suddenly you’re not full anymore.” The six FTD patients who ate the most had the greatest amount of atrophy in brain circuitry in regions called the insula and the basal ganglia. The insula is deep inside the brain, within the fissure separating the frontal and temporal lobes. Bodily sensations map to it, including sensations from the gut. So does smell. The basal ganglia and insula are thought to integrate information about body sense with decision-making. If these circuits are damaged, it might lead to a decision to overeat, even when gut sensations or hormonal messages normally might cue one to turn down that last helping, Woolley says. “I would argue that these circuits are important for resisting cues to eat,” Woolley says – cues such as an abundance of available, tasty food. “What was surprising was that patients who were overeating were not heavier than those who weren’t overeating,” he adds. Plenty of other mysteries remain. Woolley now is analyzing blood from the study participants. He’s measuring hormones that affect hunger or satiety, such as insulin, ghrelin and leptin. He wants to know if the overeaters are getting hormonal signals for fullness. If the answer is yes, then he wants to learn exactly what is going on in the brain that leads them to overeat anyway.
Related Links:Binge eating is associated with right orbitofrontal-insular-striatal atrophy in frontotemporal dementia
Woolley et al. Neurology, October 2, 2007 Frontotemporal Dementia (FTD)
UCSF Memory and Aging Center