The Cognitive Impairment Unit of the Marqués de Valdecilla University Hospital has developed a new and original test for the differential diagnosis of dementias. The study, which has been published in the Journal of Alzheimer's Disease, shows how by carrying out four drawings (turtle, strawberry, envelope and train) the researchers were able to diagnose with high precision the type of dementia suffered by a group of patients.
The project is part of the doctoral thesis of one of the unit's neuropsychologists, Ana Pozueta, which focuses on the study of a particular type of dementia called semantic dementia in which the loss of concepts is the main symptom: “Just as in Alzheimer's disease, recent memory loss is the first thing the family notes, in semantic dementia patients begin to have difficulty understanding the meaning of words and progressively stop knowing what objects are used for. “
The researchers appreciated that this loss of concepts was very characteristic in the drawings made by the patients, which were often very similar to each other and with a tendency towards prototypes: for example “by asking them to draw a duck they did it with four legs, since the prototype animal is the dog and all the drawings resembled this model, and the same happened with other categories of concepts such as vehicles ” (see figure)
The principal investigator of the study, Pascual Sánchez-Juan, says that the idea arose when he saw how the patients' drawings resembled the primitive drawings of young children. “The drawings of patients with semantic dementia reminded me a lot of those made by my 4-year-old daughter, in young children the storage structure of the concepts (semantic memory) is in development, so we decided to study their development in parallel For this, we collected drawings of hundreds of children between 4 and 7 years old who helped us better understand the phases of semantic development, which we observed to be in the opposite direction of the deterioration suffered by patients. All this information helped us to develop a test based on four drawings that is very specific to detect this type of dementia.
The test, called “Brief Drawing task”, is carried out in less than 4 minutes and, despite its simplicity, offers valuable information in the diagnosis of dementia, with the advantage that it does not depend on language, a function that often It is affected in patients with dementia.
