Categorical reasoning in Alzheimer’s disease: What is preserved?
Maileen G. Ulep, Pierre Lienard- Psychiatry and Mental health
- Cellular and Molecular Neuroscience
- Geriatrics and Gerontology
- Neurology (clinical)
- Developmental Neuroscience
- Health Policy
- Epidemiology
Abstract
Background
Semantic knowledge impairment appears to be a robust early indicator of Alzheimer’s disease (AD) pathology. The disruption of semantic cognition has been detected in preclinical AD. We investigate the ability of patients with mild to moderate AD to categorize items belonging to two semantic domains critical in daily life, living kinds and artefacts.
Method
The categorial reasoning competence of 12 patients with AD and 16 age‐matched normal controls, in the semantic domains of living kinds and man‐made objects are compared by means of an unconstrained pile‐sorting experiment. The participants are left to decide how to lump a list of items, hence, to select organizational schemes of their choosing. Unconstrained pile‐sorting has the potential to better reveal the most salient concepts and principles that orient the classificatory decisions of the participants.
Result
The experimental findings highlight both preserved and disrupted abilities. Important structural principles organizing knowledge in both semantic categories seem to remain well preserved and to still drive patients’ core reasoning. Patients and controls do differ in the specific contents of their piles, even though the number of piles generated by each group does not diverge. Patients with AD were less systematic in their categorization strategies than control participants. The performance of patients displays evidence of a broad weakening of conceptual associations at levels of categorizations requiring finer details.
Conclusion
Early deviations in cognitive performance of individuals with AD from cognitively normal adults might only appear when careful analyses of contents are conducted. To our knowledge, it is the first study to use this task as developed in cognitive anthropology to investigate semantic knowledge in AD. We propose that the detection of early deviations in performance of patients with AD might be enhanced by the combination of detailed analysis of contents and a quantitative approach.