Verbal and visuoperceptive semantic association in aMCI and AD patients

The semantic impairment in Alzheimer’s patients was been largely studied. The deficit was observed by analyzing the categorization process, the fluency ability, the event recalls, the recognition of the word/picture. Few studies were conducted on loss mechanisms of the knowledge and in specify in the degradation of semantic store and the decrease of categorization ability (see Peraita, 2004). Few studies were oriented to verify the semantic associative ability. Passafiume (2012) suggested the in the semantic degradation in the dementia the information were lost by processes that initially interest the abstract relations and later on, with the progression of the cognitive degeneration, the relation more related at the perceptual storage system. Aim of our study is to verify the progression of the loss of associative relations in cognitive deterioration not only in the dementia but in Mild Cognitive Impairment already. The sample recruited in the study was divided in 4 groups: a) 19 subjects with Amnestic Mild Cognitive Impairment (aMCI) (mean age 71,0); 16 patients with mild Alzheimer’s Disease (AD) (mean age 72,0); 20 patients with moderate AD (mean age 74,3); 20 Normal Control (NC) (mean age 68,3). An experimental tasks battery carried out to evaluate the verbal and visuoperceptual semantic association abilities and to naming tasks (verbal naming and visuoperceptive naming). Our results suggest a progressive impairment in the categorization ability tested by each experimental condition: in the naming tasks the AD patients have worse performances than NC and aMCI subjects. The statistical analysis show the performance in associative relations decreasing in the pathological groups and evidence the similar trend in semantic degradation both in visuoperceptual and verbal semantic associative tasks (F(12, 177,5)=8,2, p=0,000). The most interesting difference are in the comparison between the performance of aMCi and AD groups. The trend is confirmed even analyzing the performance of each of the 4 associative relation examined (the Function relation is the better preserved, while the Superordinate relation is the worse). Our data seems to confirm the degradation of semantic store and to clear up the loss of semantic associative relations They suggest a degradation process based on gradual loss that in first time involve the information linked in abstract cognitive area and in a second time the information better related to the perceptive storage.