In Alzheimer's disease, the loss of recognition of objects and living beings in our surroundings is not a homogeneous phenomenon. The conceptual categories of living beings and inanimate objects are affected differently, and the category of living beings seems to be better able to withstand the brain damage that Alzheimer's causes. That is the conclusion of a study carried out by a joint team of researchers hailing from the Research Group in Cognitive Neuroscience (GRNC), which is attached to the Barcelona Science Park and the Department of Basic Psychology at the University of Barcelona (UB), and from the Dementia Diagnosis and Treatment Centre at University Hospital in Bellvitge. According to the authors, the findings could be valuable in designing new memory stimulation programmes for Alzheimer's patients. The paper will appear on 1 February in the online issue of the journal Neuropsychologia (doi:10.1016/j.neuropsychologia.2007.11.018).

Albert Costa, a researcher at GRNC-Barcelona Science Park and one of the paper’s authors, said, “The study’s findings will not only provide useful information on the patterns of cognitive deterioration in Alzheimer’s patients, but they may also contribute to a better understanding of how conceptual information is organised in the brain. The fact that a disease spread throughout brain affects semantic categories differently could also suggest that conceptual information in the brain is not centralised in only a few specific areas, as was previously thought.” The four other named collaborators in the study are Mireia Hernández and Núria Sebastián Gallés, who work in the UB’s Department of Basic Psychology and are members of the GRNC-Barcelona Science Park team together with Albert Costa, and Montserrat Juncadella and Ramón Reñé, who work at the Dementia Diagnosis and Treatment Unit at University Hospital in Bellvitge.

To date, controversy has existed in the scientific community over whether the memory loss suffered by Alzheimer’s patients could exhibit different patterns for the conceptual categories of living things and inanimate objects. The main aim of the new study was to check for category-specific conceptual deficits in the memory of Alzheimer’s patients, looking at their ability to recall the meaning of words in different semantic categories, such as tools (scissors, hammer), means of transport (lorry, bus) and animate living beings (plants and animals). Our conceptual memory consists of the knowledge we have of objects in the world. For example, knowing that a plane is a means of aerial transport or that a zebra has four legs and lives in Africa is the kind of information that is stored in what is known as “semantic or conceptual memory.”

The study’s findings showed that healthy people and Alzheimer’s patients who had only presented a mild loss of semantic information were generally equal in their ability to recall the meaning of words referring both to inanimate objects and living things. By contrast, patients who had already lost considerable semantic information experienced that loss principally in relation to concepts referring to objects. However, they kept their memory of concepts referring to living things just as well as the other groups of participants who were not suffering from the disease or whose disease was in a less advanced state.