A loved one who suddenly empties the cupboards, starts eating only one food or puts anything in their mouth can disturb those around them. These confusing gestures are not always simple greed or a bad habit.
This pathology, called
frontotemporal dementiarepresents around 5% of cases of dementia but a large proportion of forms which begin before the age of 65. The first signs mainly affect behavior and personality: disinhibition, rigidity, loss of empathy, then language disorders. For some patients, however, it all starts on the plate.
Disrupted eating habits: a key marker of frontotemporal dementia
SISSA researchers describe a wide range of eating disorders in these patients. Their review states:
“Several findings reveal that such changes in eating behavior are more common in patients with frontotemporal dementia (FTD) than in people with other types of dementia. Furthermore, dietary changes may differ between the two variants of the disease, namely the behavioral variant and semantic dementia (SD).”
Binges, fixation on certain foods or refusal to eat anything other than a very limited menu often come up in medical records.
People with FTD sometimes take food from other guests or completely ignore their dietary restrictions, such as diabetes.
“These behaviors can be problematic both physically and socially. said Marilena Aiello, researcher at SISSA (International School for Advanced Studies), quoted by Get Surrey. She adds: “Patients tend to gain weight. Although, in some extreme cases, they lose weight due to obsessive consumption of a single food.”
Why these eating disorders can herald frontotemporal dementia
In the behavioral variant of frontotemporal lobar degeneration, diagnostic criteria includehyperorality and marked changes in eating behaviors. These repetitive gestures around food are among the major signs, at the same level as disinhibition or loss of empathy, and can precede memory problems by several years. Studies show that eating abnormalities – hyperphagia, appetite for sweets, rigid table rituals – are much more common in FTD than in Alzheimer’s disease.
Researchers do not yet have all the answers about the mechanisms. One lead is a disruption of the autonomic nervous system, which confuses the signals of hunger, satiety and appetite. Lesions of the hypothalamus, but also of the orbitofrontal cortex, the insula and the striatum, circuits of impulse control and reward, can promote uncontrolled food intake or the fact of putting inedible objects in the mouth.
Appetite changes: when to talk to a doctor about frontotemporal dementia
This form of dementia remains rare – 1 in 20 cases – and most variations in appetite have other causes. The worry arises rather from a sudden, compulsive change, embarrassing for those around them, associated with inappropriate comments, increased rigidity or language difficulties.
If in doubt, a doctor can refer you to a memory consultation or a reference center.