Strange table manners could be more than just quirks, they may be an early sign of dementia, experts have warned. 

Frontotemporal dementia, which affects actor Bruce Willis and around 60,000 other Americans, arises from a gradual decline in the brain regions associated with personality and language skills.

Symptoms to watch out for include personality and behavior changes, such as impulsiveness or lack of empathy, along with language difficulties, where sufferers struggle to find words.

However, experts point out that a less well-known symptom of this condition is ‘obsessive and repetitive behaviors’ that can affect a patient’s dietary and eating preferences.

According to researchers in DC, patients may develop a fixation on a particular food, refusing to consume anything else. They might also eat non-food items or take food from others’ plates.

Dr. Marilena Aiello, a neuroscientist who studies this condition, previously stated: ‘These behaviors are problematic socially, and they also pose health risks for patients since they tend to gain weight.’

‘[But], some people lose weight because they eat a narrow range of foods in an obsessive way.’

The exact reason for this behavior is unclear, but researchers suggest it may be linked to changes in the body’s hunger and fullness signals.

Bruce Willis, pictured above with wife Emma Heming in July 2018, suffers from frontotemporal dementia

It is not known whether Bruce Willis suffers from any compulsive eating behaviors as a result of his condition, but his family has said he is struggling with communication.

And earlier this month, his wife Emma Heming Willis revealed the subtle sign she noticed shortly before his diagnosis.

She told ABC News: ‘For someone who is really talkative, very engaged, he was just a little more quiet, and when the family would get together he would kind of just melt a little bit.’

He also soon began losing words, she said, and a stutter he dealt with as a child returned.

‘[He] felt very removed, a little cold, not like Bruce, who is very warm and affectionate. 

‘Going the complete opposite of that was alarming and scary,’ she added.

In frontotemporal dementia, behavioral changes are normally the first noticeable sign of the disease. In Alzheimer’s, for comparison, which affects up to 6.7 million people,  the first signs are normally memory loss or confusion with time or place.

Over time, more areas of the brain degenerate, meaning patients with frontotemporal dementia often eventually mirror those with late-stage Alzheimer’s.

Experts say that people suffering from the condition may have compulsive eating behaviors (stock image)

Other symptoms of frontotemporal dementia include difficulty eating or swallowing, trouble walking and vulnerability to infections.

The condition is not normally fatal on its own, but weakens the body and raises the risk of life-threatening infections or other complications. This may include problems swallowing or eating and drinking.

There is no cure for the disease, although some drugs and therapies may help to slow the progression of the symptoms.

It is also not clear what causes frontotemporal dementia, although it has previously been linked to a build-up of protein clumps in the brain.

Some researchers say it can also be caused by damage to blood vessels in the brain, which they say can affect the supply of nutrients and oxygen to brain cells.