The patient’s condition deteriorates over the years. The symptoms of FTD vary greatly from one patient to another, both in their appearance and in the order in which they develop.
In the early stages of FTD, behavioural problems are discreet and may reflect the effects of fatigue, stress or depression.
The first symptoms are often mental fatigue or apathy, loss of motivation, indifference to emotions and to others, even loved ones, or loss of desire.
A second, more visible, type of symptom is behavioural problems such as a high level of disinhibition and an inability to respect social codes – inappropriate thoughts, failure to respect rules when driving or in public spaces. There may also be great agitation or even aggression, running away or the development of obsessions. Patients may act strangely, for example by continually repeating the same gestures, fixating on certain habits or objects and becoming compulsive collectors. Some patients may have an irrepressible need to move, such as walking several kilometres for no specific purpose. A lack of patience and excessive irritability are sometimes observed.
Changes in eating behaviour are also present in many sufferers, such as gluttony – eating excessively and in a hurry – or phases of bulimia or anorexia.
In some cases, patients may neglect themselves, with a loss of personal hygiene and clothing.
Language disorders in FTD can take different forms, affecting either syntax (meaning of words) or fluency:
- Aphasia is a loss of speech manifested by difficulties in pronouncing words, a loss of vocabulary and even, in more advanced stages, a total inability to speak. However, the ability to understand words is preserved.
- Semantic dementia, in which it is comprehension that is affected rather than pronunciation, occurs when the left side of the brain is more affected. Patients are then unable to name objects (anomic aphasia) or recognise the faces of close relatives (prosopagnosia).
Other disorders follow, in particular confusion, impaired judgement and planning, with patients unable to carry out simple tasks.
Motor symptoms may appear at an advanced stage of the disease, such as rigidity of movement or walking difficulties. FTD is first suspected through the testimony of relatives who report changes in a parent’s behaviour, personality or language difficulties.
Additional tests are then carried out to confirm the diagnosis of FTD. Firstly, neuropsychological tests are used to assess patients’ reasoning, judgement, attention and memory. Brain imaging tests, such as MRI or CT scans, reveal atrophy of the frontal and temporal regions. Biological tests, a lumbar puncture or an electroencephalogram are used to rule out other pathologies with similar symptoms.
For familial genetic forms, which account for around 50% of cases, a consultation and genetic analysis may be offered to identify the mutation causing the disease.
At the Paris Brain Institute
One of the key objectives of the research being carried out at the Brain Institute and the IM2A is to improve the diagnosis of patients, so as to detect the disease earlier and limit diagnostic error. FTD can be confused with a number of illnesses depending on its stage, such as mood disorders (depression, bipolar disorder) or anxiety disorders (obsessive-compulsive disorder), or even Alzheimer’s disease.
Isabelle Le Ber and Paola Caroppo, in collaboration with the neuroimaging teams and the Clinical Investigation Centre at the Institut du Cerveau, have used cutting-edge brain imaging techniques to identify a very limited region of the brain involved in understanding language, interacting with others and recognising facial emotions (impaired in FTD patients), which could be the site of the first brain lesions in a genetic form of FTD. This major discovery has made it possible to locate the site of the biological mechanisms, in particular neuronal death, even before the onset of clinical symptoms.
Patients with frontotemporal dementia (FTD) are unable to categorise objects. By studying patients with lesions of the frontal cortex, researchers in the “FRONTLAB: Functions and dysfunctions of frontal systems” team led by Dr Richard Lévy have demonstrated that categorisation in the brain involves different functions, on the one hand the ability to gather information and on the other, the capacity for abstraction. These two mechanisms depend on specific regions within the frontal lobes. This study paves the way for the use of concept formation tests as a diagnostic tool for FTD.
A study by Marc Teichmann and Carole Azuar from Professor Richard LEVY’s team at the Institut du Cerveau and the Pitié-Salpêtrière-APHP hospital has revealed a particularly marked impairment of moral emotions, such as admiration, shame or pity, in patients with frontotemporal degeneration. The results pave the way for early, sensitive and specific diagnosis of FTD patients.