Patients with fronto-temporal dementia need specific and appropriate medical care. However, this disease is still too often confused with Alzheimer's disease. Clinicians and researchers from Paris Brain Institute and from the Memory and Alzheimer's Disease Institute (IM2A), in collaboration with an international team, have just demonstrated that simple tests evaluating empathy could guide the diagnosis.
Alzheimer's or frontotemporal dementia ? Not so easy to differenciate. Frontotemporal Dementia (FTD) comes indeed in three clinical forms, the most common –the so-called frontal or behavioural variant(fv)- causes memory disorders. This often overlooked fact tends to diagnose some patients with Alzheimer's disease by mistake. But this could change soon : Maxime Bertoux (unit 975 Inserm/CNRS/Pierre and Marie Curie University, Brain and Spine Institute, Paris), in collaboration with an international team, has shown that the social cognition assessment could be an efficient tool to distinguish both diseases : "social cognition is the set of cognitive abilities enabling someone to adapt to his social environment," explains the researcher.
Researchers used two tests for their study : one is to ask the patient to recognize emotions in frontal face pictures ; in the second, the "stumble" test, life scenes are described to the patient, who has to figure out those who are, or are not socially embarrassing. The goal was to evaluate whether these two combined tests are relevant for differentiating patients with FTDfV from those with Alzheimer's disease.
Researchers retrospectively analyzed the record of 96 patients received at the cognitive and behavioural disease Centre in the Pitié-Salpêtrière hospital (Paris) and with one of the two diseases. All had received an initial check-up with imaging, cerebrospinal fluid analysis (CSF), memory tests and social cognition tests - the so-called mini-SEA tests (social cognition and emotional assessment). The analysis consisted in determining if the results of these last two examination types were consistent with the diagnosis selected by the medical team on the basis of the performed diagnostic tests results. "We found that 85 to 94% patients can be classified in the right group –Alzheimer's or FTDfv- relying solely on mini-SEA tests. Comparatively, the result is only 70% with only memory tests, which in practice means an inaccurate diagnosis of Alzheimer's disease in a FTD patient out of two ". A grey zone remained in 11% cases : "the tests fail to direct to either disease. The concerned patients are at an advanced stage, for whom cognitive impairment becomes more general ". In an early diagnosis situation, this problem does not usually exist.
A SIMPLE DIAGNOSTIC TEST TO INTEGRATE ROUTINELY
FTD accounts for 20% of degenerative dementias, and nearly one-third of cases diagnosed in patients under 65. If the frontal variant can be confused with Alzheimer's disease, it is often distinguished through personality disorders, a disruption of the sense of social values... which require well-specific medical and psychosocial care. "This study could therefore be useful to review the diagnostic criteria of both diseases," explains the researcher, and thus provide more appropriate support".
In the meantime, the authors of this study insist that " doctors and neuropsychologists should be aware of the fact that the distinction between Alzheimer's and FTD may not be based solely on memory tests : social cognition tests have here a crucial importance ". Quick and inexpensive, these could, in the medium term, be one of the reference diagnostic tests. "But to improve the precocity of the diagnosis of these diseases, identification of impaired neuronal and cognitive decline new markers is required." This is the challenge set by several authors, within a brand new research institute on dementias, located within the East Anglia British university (Norwich, England).
