FrontoTemporal Dementia (FTD)
Frontotemporal dementia (DFT) are very heterogeneous neurodegenerative diseases sharing a specific lesion localization into the anterior part of the frontal and temporal brain lobes.
In Human, those brain areas are regulating the regulation functions of social behavior, initiatives, analysis and generation of emotions. Left frontal and temporal lobes areas are also strongly involved into speech functions in right-handed but also in a large portion of left-handed persons. The main DFT consequences are change of patients’ behavior and speech skills.
The DFTs start generally at an age between 50 and 65 (rarely after 70) but the diagnosis is generally made only after 65 as the symptoms are generally badly recognized or interpreted at the start of the disease. The DFTs are the second cause of cognitive disorders for young patients. It affect equally both male and female.
In 40% of patients, there is a family history evoking a hereditary transmission (a relative has presented similar disorders with cognitive, speech or behavioral symptoms). Such hereditary forms of DFT are related to gene mutations, principally the progranuline, the protein Tau or the C90RF72 genes. Genetic counseling can be proposed in such situation.
DFTs are complex diseases in term of symptom expressions but also in term of brain lesions. Indeed, microscopically, DFTs correspond to 10 different diseases related to dysfunctions of some neuronal proteins such as Tau, TDP-43 or FUS… It is difficult to predict in one patient, the exact type of DFT observed. The definitive diagnostic can only be made by tissue analyses of donated brain after the death of the patient.
Considering this fact, the disease progression can be very variable between patients. A rapid diagnosis will be beneficial as some consequences of detrimental behaviors can be avoid quickly.
Depending of the clinical signs, three variants of DFT are described even if some overlaps exist.
Behavioural variant frontotemporal dementia
This variant correspond to the typical DFT. Behavioral disorders are predominant and can be wrongly attributed to a psychiatric disease (depression or other). The main symptoms are very characteristic and present different degree:
Apathy: It corresponds to a lack of initiative or enthousiasm to perform activities. Te patient apprears passive or let down his/her activities quickly after start. The patient need to be stimulated and can stay inactive in his/her chair or bed for a long time.
Desinhibition : The patient show a non-adapted social behaviors. He/she can be too familiar and do not respect basic social rules. He/she can perform impulsive actions without thinking about the consequences. He/she can be rude and spend thoughtlessly huge amount of money. The patient neglects his/her physical appearance and personal hygiene
Lack or low level of empathy: the patient can not anymore read and understand other people’s emotions or consider their point of view. The patient is insensitive to surrounding events. He/she become more and more distant, even if, paradoxically, he/she can maintain very strong relation with some specific person or pet
Stereotypy and everyday rituals: The patient acquires some tics, repetitive or ritual gestures. Some activities become rituals such as outside walk, key-word games at fixed time in the days. The patient can repeat numerous times the same word or sentence…
Eating disorder: Some changes in the patient’s eating habits are observed. The patient eats very quickly sometime inducing choke when swallowing. He can also have an addiction for sweets, cakes, tobacco and alcohol.
Some capacities are well preserved: The patient generally keeps a good time and space orientation. He/she doesn’t lose his/her way. His recent event memory and gesture skills are preserved.
Non fluent progressive aphasia
This DFT variant is characterized by a progressive reduction of the patients’ speech skills. He/she can experiment “missing words”, use generic words such as “stuff”, “this thing”, has difficulties to build sentence and to make him/her understood. It progress slowly toward stronger speech impoverishment and mutism which contrasts with the preserved cognitive and behavioral skills for numerous years.
Semantic dementia
It is a rare DFT variant characterized by the loss of the word meaning and the loss of general or people knowledge. The patient doesn’t understand anymore some word and are confused in front of usual objects, not knowing for example if a pineapple can be eaten with or without it skin or how to use a whistle… A change of personality toward an egocentric, overfamiliar or obsessional behavior is also frequently observed.
The DFT diagnosis will be based on:
A very precise description of the behavioral and speech disorders observed;
An observation in the brain image of a dysfunction in frontal and temporal area of the brain (MRI, SPECTS)
A genetic blood screening if an hereditary disease is suspected and only if a signed consent from the patient or his/her guardian is obtained.
There is unfortunately no cure for FTD. However, some drugs can help to control behavioral disorders such as antidepressants or other molecules like Trazodone. The establishment of such treatments must be done in a specialized medical center.
FTD clinical care is mainly based on clear explanations of the symptoms and preventive measures against dangerous events (going out, prevention of choking hazard), daily stimulation for the patient to fight against apathy and social disinterest. Cognitive rehabilitation sessions at home by specialized teams are highly appreciated. A speech therapy is indicated to help in case of speech or swallowing disorders.
Clinical therapeutic trials are currently rare but some hopes are recently raised, including the genetic forms of FTD.
Caregiving support is crucial and is provided by clinical psychologists, family associations and caregiver support groups.
Behavior disorders are very difficult to cope with and patient hospitalization in specialized units can be considered to evaluate again of the symptoms, to adjust treatments, to test new activities for the patient while allowing a rest period for the caregiver.
Some behavior modifications such as excessive and impulsive expenses can induce legal authorities to decide lifeguard measures (protection of the court, curatorship or guardianship).
