Changes in semantic memory are a controversial topic in research on cognitive decline in aging. In this study, we analyzed whether the semantic deficits in mild Alzheimer's disease (AD) reflect the information acquisition process, and whether the deficits are related to when the information was initially stored. We hypothesized that in the earlier stages of dementia, the ability to access semantic associative relations reflects the use of these associations during different developmental stages. Specifically, we asserted that Alzheimer's patients might be able to access the relations that are learned earlier in life for the longest amount of time compared to those that are learned later. In this study, 254 subjects were divided into four groups (child, adult, senior, and Alzheimer's patients groups) and were evaluated with an experimental semantic association task that incorporated five semantic associative relations that were used to compare performance by age group. An analysis of variance (ANOVA) 4 × 5 test showed a significant main group effect, F(3, 250) = 97.1, p < .001, and an associative relations effect, F(4, 1000) = 23.1, p < .001, as well as an interaction of Group × Associative Relations, F(12, 1000) = 8.5, p < .001. The results demonstrated that the semantic associative relations that were acquired in later developmental stages were less preserved in persons with mild AD (i.e., superordinate relation, p < .0001). On the contrary, the semantic relations acquired earlier in childhood were better preserved in persons with mild AD. Our results suggest that semantic impairment begins with difficulties in using the associative relations that link concepts together in the semantic memory of patients with mild AD dementia (and possibly in individuals with mild cognitive impairment).

Deterioration of semantic memory is one of the primary neuropsychological deficits caused by Alzheimer's disease (AD). In this study, we hypothesize that the breakdown of semantic memory in the mild-to-moderate stage of AD is due to the disruption of the semantic network that links the concepts. Furthermore, the loss of these links is not homogeneous through the semantic association categories (i.e., Superordinate, Contiguity, Part/Whole, Attribute, Function). Twenty-two subjects (11 patients with mild-to-moderate dementia and 11 control subjects matched on demographics) participated in the study. Both controls and patients with AD underwent extensive neuropsychological evaluation and three experimental tasks: (1) Naming Task, (2) Semantic Association Task, and (3) Semantic Knowledge Task. Results showed that: (1) The AD group was significantly different from the normal controls group in all the experimental tasks; (2) the Semantic Association Task was significantly worse than the other tasks; (3) for the AD group, the scores of the Function and Part/Whole association categories were higher than in the other categories; and (4) living stimuli were more impaired than nonliving. These data confirm prior research showing the semantic association is differently impaired in AD patients.

We analysed the organisation of semantic network using associative mechanisms between different types of information and studied the progression of the use of these associative relations during development. We aimed to verify the linkage of concepts with the use of semantic associative relations. The goal of this study was to analyse the cognitive ability to use associative relations between various items when describing old and/or new concepts. We examined the performance of 100 subjects between the ages of 4 and 7 years on an experimental task using five associative relations based on verbal encoding. The results showed that children are able to use the five semantic associative relations at age 4, but performance with each of the different associative relations improves at different times during development. Functional and part/whole relations develop at an early age, whereas the superordinate relations develop later. Our study clarified the characteristics of the progression of semantic associations during development as well as the roles that associative relations play in the structure and improvement of the semantic store.