Explainer: how is frontotemporal dementia different and what are the warning signs?
Not all types of dementia start with memory loss, explain Stephanie Wong, Fiona Kumfor, and Rosalind Hutchings.
When most people hear about dementia, they picture older people with memory loss. But not all types of dementia start with memory loss.
In the same way cancer can be classified as melanoma, prostate cancer or bowel cancer, dementia can also be classified into many different types. The most common type is Alzheimer’s disease, which affects the parts of the brain responsible for memory.
In other types of dementia, the first symptoms may include changes in personality and behaviour. These types of symptoms are prominent in frontotemporal dementia.
Frontotemporal dementia is a common cause of dementia in people under the age of 65. New research from our clinic has helped us to understand the common symptoms.
Individuals with frontotemporal dementia have atrophy (or shrinkage) of the frontal lobes of the brain. The frontal lobes are important for controlling voluntary behaviour, emotions and complex thought.
One carer described how her husband would inappropriately approach young women, often interrupt conversations and make offensive remarks about other people’s appearances. This was completely out of character for him.
The symptoms are diverse and can differ from person to person.
Currently there is no diagnostic test for frontotemporal dementia. So, to diagnose frontotemporal dementia we rely on careful assessment of a person’s symptoms. Six key symptoms are recognised, and individuals must show a combination of these symptoms to be diagnosed.
Some people make impulsive decisions (also known as disinhibition). People with frontotemporal dementia often overspend, gamble or buy items for which they have little use. This makes them particularly susceptible to financial scams or exploitation. In one instance, a man sent large sums of money to what he thought was a charitable organisation, to the point where he needed to withdraw from his superannuation and sell his house to cover the enormous debt he had incurred.
Other people become apathetic or lose motivation or interest in doing things. If left to their own devices, a person with frontotemporal dementia will often sit in front of the television, unable to initiate any purposeful behaviour. They show a loss of interest in activities or hobbies they previously enjoyed, and require prompting to engage with others. Research in frontotemporal dementia has linked apathy to damage in key areas of the brain that process rewards.
Some individuals show reduced empathy, which refers to the ability to understand and share how somebody else is feeling. Carers often report their loved ones no longer respond appropriately to other people’s emotions. This apparent lack of concern can sometimes be misinterpreted as self-centeredness. Our new research found people with frontotemporal dementia have difficulty interpreting facial information that is vital for recognising emotions.
Changes in eating behaviour can occur in people with frontotemporal dementia. They will often overeat or show an increased preference for sugary foods (in one example, eating two tubs of ice-cream every night). These changes in eating behaviour have been linked with disruptions to the brain’s endocrine, autonomic and reward-processing systems.
Some people with frontotemporal dementia show patterns of repetitive or ritualistic behaviour. Examples include obsessions with counting and clock-watching, restricted interests in leisure activities or hobbies, and rigid adherence to certain daily routines or food preferences.
People with frontotemporal dementia often have problems with complex thinking. Tasks such as planning a trip to the doctor or working out how much change to expect from the cashier can be challenging.
Family members of patients with frontotemporal dementia often find these behavioural changes more distressing and difficult to deal with than memory loss. Because these changes seem so diverse and unrelated, current research and clinical practice tend to treat each symptom separately. And the available treatments are limited in their effectiveness.
In our recent review article, we identified a common thread that links these seemingly unrelated behavioural symptoms. It appears that disinhibition, apathy, reduced empathy, overeating and repetitive actions can all be traced back to shrinking of brain areas that control goal-directed behaviour.
Goal-directed behaviour allows us to modify our actions to achieve certain goals or desires. For example, if you feel thirsty you will go to the fridge and get a drink. If you want a job promotion you will work hard and make sure you don’t offend your co-workers. If you enjoy skiing you might go on a trip to the snow.
When the brain’s goal-directed behaviour system goes awry, an individual may have difficulty choosing whether to continue eating despite feeling full, respond to another person’s distress, approach strangers or engage in their hobbies. As a result of losing goal-directed control, behaviour can become restricted and repetitive.
Where to from here?
Limited awareness of frontotemporal dementia and the diversity of its symptoms often lead to misdiagnosis or delays in diagnosis. Behavioural changes tend to be mistaken for symptoms of depression or psychiatric disorders.
Educating the general public and health professionals about the different types of dementia and the variety of symptoms is an important step in reducing the time it takes to reach a diagnosis.
In the absence of a cure, a major challenge is to develop appropriate and effective management strategies for those living with dementia. We hope this new research can help us find interventions for these often misunderstood symptoms.