Frontotemporal dementia is a form of dementia characterized by behavioral and language disorders associated with cognitive decline.
Clinicians distinguish between three forms of frontotemporal dementia based on the signs and symptoms that affect the individual:
- Behavioral-variant frontotemporal dementia.
- semantic dementia
- Progressive non-fluent aphasia
Pick’s disease is also considered one of the forms of frontotemporal degeneration, manifested by changes in behavior: isolation, disinhibition, neglect of hygiene, distraction or continual repetition of the same gestures.
At first, frontotemporal dementia is mainly manifested by behavioral and language disorders that appear together or successively over time. They vary from patient to patient.
As it occurs remembered at a young age, it can be difficult to differentiate it from schizophrenia or an affective disorder.
Most often, behavioral problems predominate.
The majority of cases (about 70%) are sporadic (i.e. isolated cases with no hereditary form). There are therefore approximately 30% of familial cases of FTD which can be caused by at least four known genes (the tau and progranulin genes, and more rarely the VCP and CHMP2B genes).
Most often, the genetic anomaly seems to be transmitted autosomally (from generation to generation), which means that the patient has a risk in two of transmitting the disease to his children.
Prevalence of frontotemporal dementia
The prevalence (number of patients affected at a given time) of frontotemporal dementia varies between 3 and 15 cases per 100,000 people. It increases with age. Men seem to be more affected than women.
It is the 3rd cause of degenerative dementia. It represents 15 to 20% of the causes of dementia.
The age of onset is in the late 50s (range ages 20 to 75).
Life expectancy, from the moment of diagnosis, is on average about ten years.
Signs and Symptoms of Frontotemporal Dementia
1. Behavioral variant of frontotemporal dementia
This form affects about 60% of patients with one of the three forms of frontotemporal dementia.
The diagnostic criteria for this form are:
A. Progressive deterioration in behavior and/or cognition.
B. Three of the six behavioral/cognitive symptoms must be present. Rather, they must be persistent or recurring.
• Early disinhibition: inappropriate social behavior, loss of propriety or politeness and/or impulsive, thoughtless or even reckless acts. Disinhibition results in foul language, familiarity, or inappropriate attitudes (for example, they undress, behave badly at the table, urinate in public, etc.).
• Early apathy/inertia.
• Early loss of sympathy or empathy: diminished response to other people’s needs and feelings and/or social disinterest, impaired interpersonal relationships, emotional blunting.
• Early stereotyped or compulsive/obsessional behavior: simple repetitive movements, complex compulsive behaviors and/or verbal stereotypies: the patient repeats the same gestures, has fixed time habits, becomes fixated on certain objects or practices certain hobbies to excess such as the casino.
• Hyperorality and change in eating habits: changes in food tastes and/or gluttony, increased consumption of alcohol or cigarettes.
• Neuropsychological profile: executive function deficit and relative loss of episodic memory and visuo-spatial functions.
2. Semantic dementia
It concerns about 20% of cases and is mainly characterized by language disorders.
• Anomie-type disorders (difficulty finding words) despite preserved verbal fluency. For example, the person uses the word « bird » rather than « sparrow » or « thing, thing » rather than the appropriate word. Understanding is preserved.
• In more severe cases, the patient has problems identifying objects or animals. He can for example ask the following question: « What is a bird? » « . The person can, however, continue to manipulate numbers.
From an anatomical point of view, it is characterized by atrophy of the left temporal lobe.
3. Progressive non-fluent aphasia
It concerns about 20% of cases and is also characterized by language disorders. The person generally speaks slowly, has difficulty understanding the meaning of words, lacks verbal fluency, has great difficulty speaking on the telephone, expressing himself within a group or understanding complex sentences. Many of them develop Parkinson’s-like motor symptoms (for example, muscle rigidity in the arms and legs).
At the onset of the disease, memory impairment is minimal. Neuropsychological tests indicate that the information is well stored by the patient’s brain but that it has difficulty in being restored (for example, the patient does not retain such and such a word unless given a clue).
Fronto-temporal atrophy predominates in the left hemisphere, with a language disorder on expression, comprehension being relatively preserved.
• Judgment and planning problems: patients cannot plan an activity.
• Swallowing disorders (severe stage of the disease).
Evaluation of frontotemporal dementia
The Frontal Dysfunction Scale assesses the severity of behavioral disturbances in patients with mild-stage dementia.
What brain imaging says
Unlike Alzheimer’s disease, which affects almost the entire brain, frontotemporal dementia preferentially affects the temporal lobe and the frontal lobe.
Neuroimaging techniques have made it possible to observe lesions of the frontal lobes (seat of reasoning, abstract ideas, planning, motor skills) and temporal (seat of the formation and retrieval of memories), and sometimes the lobes parietals.
In the late phase of the disease, there is significant neuronal loss in the cortex.
Magnetic resonance imaging (MRI) or CT scans are used to support a diagnosis of frontotemporal dementia.
Single photon emission computed tomography (SPECT) is an imaging technique that assesses the activity of the frontal and temporal lobes (in DFT, this activity is decreased).
These techniques do not make it possible to distinguish between the different forms of frontotemporal dementia. Detecting Pick’s bodies can only be done on post-mortem tissues (i.e. after autopsy).
Frontotemporal dementia can be confused with many other neuropsychiatric diseases, especially early in the disease; eg depression, bipolar or obsessive-compulsive disorder), with a tumor of the frontal lobe, head trauma, certain infectious diseases, dementia associated with movement pathology or vascular dementia or chronic alcoholism.
Alzheimer’s disease is distinguished from frontotemporal dementia by early memory and orientation disorders marked from the onset of the disease.
Medicines are prescribed in low doses at the beginning of treatment, before these are gradually increased according to possible side effects.
Antidepressants are used to treat the following disorders:
• Anxiety and panic attack
• Obsessive Compulsive Disorder
Selective serotonin reuptake inhibitors are the types of antidepressants of choice:
fluoxetine (Prozac®), sertraline (Zoloft®), paroxetine (Paxil®), fluvoxamine (Luvox®), citalopram (Celexa®), escitalopram (Lexapro®).
Antipsychotics are prescribed in low doses to reduce aggression, obsessive/compulsive disorder, irrational behavior with, however, undesirable side effects: weight gain, slowed thoughts, increased risk of heart disease. Atypical antipsychotics are the types of antipsychotics of choice: olanzepine (Zyprexa®), quetiapine (Seroquel® or Ketipinor®), risperidone (Risperdal®), ziprasidone (Geodon®), aripiprazole (Abilify®), paliperidone (Invega®). Memantine, a drug already used in moderate to severe forms of Alzheimer’s disease, would improve the memory function of patients with frontotemporal dementia.
A training program combining aerobic (walking) and strength training is beneficial for the patient (for example the practice of cardiovascular exercises for 30 minutes 2 to 4 times a week, in the form of walking for example).
Mrs X, 79 years old, is being followed by a neurologist because she has mild cognitive deficits (mini mental state examination score of 26 out of 30). She was subsequently hospitalized for behavioral problems with periods of agitation and delusional disorders.
His entourage indicates that these behavioral changes appeared 4 years ago, with sometimes running away, compulsive shopping and a lack of social etiquette.
Treatment consisted of prescribing an antipsychotic (risperidone), a mood stabilizer (Valproate) and an antidepressant.
There is also a reduction in verbal fluency while episodic and visuo-spatial memories appear normal.
Neuroimaging reveals decreased activity in the frontal cortex and temporal lobe.
A diagnosis of frontotemporal dementia (degeneration) is made. His cognitive performance deteriorates with, in particular, a loss of language.
As a reminder, the symptoms of frontotemporal dementia are characterized:
- In three quarters of cases by apathy, depression.
- In a quarter of cases by mania, disinhibition (loss of social etiquette), hypersexuality and compulsive shopping.
- Mild cognitive deficits at the onset of the disease (no memory loss).
- Attention and executive function disorders.
- Eating disorders (especially bulimia).
Treatment is limited to antidepressants and mood stabilizers.
Frontotemporal dementia linked to abnormal eating behavior
Patients with frontotemporal dementia have inappropriate eating habits.
While patients with the behavioral variant overeat (especially foods high in sugar) patients with semantic dementia (another form of frontotemporal dementia) exhibit very rigid eating behavior, sometimes focusing on a specific food .
Brain imaging has also suggested that these eating habits are controlled by complex neural networks rather than a particular brain structure.
Frontotemporal dementia (FTD) is the second leading cause of dementia occurring in people under the age of 65. There are several types of FTD: the behavioral variant which is manifested in particular by inappropriate behavior and an inability to plan, while semantic dementia is characterized by a loss of the meaning of words.
“It is possible that changing dietary habits may have a protective role in frontotemporal dementia. It is necessary to know if we can change these eating behaviors and if it will make a difference,” says the study’s lead author.
49 patients with three different types of dementia (19 with the behavioral variant, 15 with semantic dementia, and 15 with Alzheimer’s disease) participated in the study. Their eating habits were compared with those of 25 healthy controls.
All participants fasted overnight and then received a breakfast buffet. The researchers calculated the total amount and type of food eaten.
The results showed that all patients with the behavioral variant consumed more calories than the other participants, with an average of 1344 calories, compared to 710 calories for the Alzheimer group, 573 calories for the semantic dementia group and 603 calories for group control.
“Patients with the behavioral variant who ate the least even consumed more calories than those in the other groups who ate the most. »
In contrast, patients with semantic dementia showed rigid eating behavior, often refusing to eat the food offered.
The lead author (Dr. Ahmed) noted that sugar craving appears to be a particular feature of the behavioral variant of FTD.
It is possible that these patients have changes in their metabolism that could be the cause of the overeating.
The researchers also studied the participants’ brains (with the behavioral variant) using MRI to look for dysfunctions in specific areas of the brain. They found that overeating is associated with complex brain networks involved in reward, autonomic function, and vision, not specific brain structure.
Source: Rebekah M. Ahmed et al. Eating Disruption and Associated Eating Behavior Assessment of Neural Networks in Frontotemporal Dementia. JAMA Neurol. 2016; 73 (3): 282-290.
Patients with frontotemporal dementia have less emotion
An Australian study has shown for the first time why patients suffering from frontotemporal dementia have less emotion when faced with a memory.
This explains why they feel no emotion when they remember a significant event (e.g. a wedding or a funeral).
Professor Piguet, author of the study, says, “Until now, we knew that emotional memories were linked to the amygdala, a region of the brain involved in emotions.
This study is the first to demonstrate the involvement of another structure, the orbitofrontal cortex, in this process. »
Another researcher in the group, Fiona Kumfor, argues that these findings will help caregivers better understand why their sick loved ones may have difficulty interacting with them.
“Imagine attending your daughter’s wedding, or meeting your grandchild for the first time, but the event is as memorable as grocery shopping, says Dr. Kumfor.
Source: The orbitofrontal cortex is involved in emotional enhancement of memory: evidence from the dementias. Brain, 2013.