04:34am Monday 18 November 2019

“Hey! You stole my food!”

Frontotemporal dementia is associated with a wide variety of abnormal eating behaviors such as
hyperphagia, fixations on one kind of food, even ingestion of inanimate objects, making an
already-difficult situation even worse. A review by SISSA researchers gathers together the state
of the art of what is known in this field, paying particular attention to the brain mechanisms
involved. The information may be used for understanding eating disorders in healthy people. The
review was published in the magazine Neurocase.

The “Banana lady” described by Andrew Kertesz (“The Banana Lady and Other Stories of Curious
Behavior and Speech,” 2006) ate only bananas and drank liters and liters of milk every day. She
continually asked her husband to make sure that there was always enough milk and bananas in
the house. After her death, brain analysis confirmed her doctors’ diagnosis: the woman was
suffering from frontotemporal dementia, a common type of dementia second only to
Alzheimer’s. Alterations in eating behavior are so frequent in this disease that they are factored
into the diagnosis. A systematic review by SISSA Researcher, Marilena Aiello, in collaboration
with Vincenzo Silani (IRCCS Istituto Auxologico Milan) and Raffaella Rumiati, SISSA professor and
coordinator of the iNSuLa laboratory (Neuroscience and Society), provides an overview of the
research done in this field, creating a comprehensive framework to help establish the state of the
art and suggest new lines of research. “We put together what appeared to be a fragmented
image, focusing on types of disorders and hypotheses about the brain mechanisms behind them,”
says Aiello. “This could be helpful for understanding abnormal eating behavior in healthy people
as well.”

There are many kinds of disorders described in the literature, ranging from a simple increase in
appetite, to uncontrolled overeating, lack of satiety, changes in food preferences as in the
extreme example of the so-called “Banana lady,” and ingesting objects .
There have been other rather extravagant behaviors related to food observed as well, such as
stealing food from other peoples’ plates. “These behaviors are problematic, of course, socially,
but also with regard to patients’ health as they tend to gain weight,” says Aiello, “even if
individual consequences are different. Some people lose weight because they eat a narrow range
of foods in an obsessive way.”

From an analysis of the studies in the review, there is a link with certain areas of the brain,
including the orbitofrontal cortex and most probably the hypothalamus, an area of the brain that
regulates the interaction between the amount of food consumed and energetic homeostasis.
“The origin of food anomalies in frontotemporal dementia is likely due to many factors,” says
Aiello. “It may involve an alteration of the autonomic nervous system, characterized by an altered
assessment of the body’s signals, such as hunger, satiety, and appetite. Damage to the
hypothalamus can cause a loss of inhibitory signals, causing behaviors such as overeating.”There
are probably sensory and cognitive factors that can complicate the picture, continues Aiello. “In
patients who eat objects, for example, there is perhaps a semantic problem of recognizing the
object of and its function.”

“All of these mechanisms,” concludes Aiello, “are interesting for understanding the disease and
creating optimal treatments to counteract symptoms. At the same time, they reveal
abnormalities that may be present, albeit with varied intensities, in healthy individuals with
irregular eating habits.”

Link to the original paper on Neurocase.

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