Deficient Visuospatial Incidental and Intentional Memory in Cognitively Healthy Middle-Aged First-Degree Descendants...

Background/Objectives: Several studies have reported cognitive decline and alterations in neural substrates among non-cognitively impaired direct descendants of Alzheimer's disease patients. Visuospatial incidental memory declines early in adulthood and may serve as a sensitive tool to detect preclinical deterioration in this vulnerable population. To test this, we characterized the incidental/intentional visuospatial memory of cognitively healthy middle-aged (35-55) descendants of Alzheimer's disease patients. Methods: Male and female first-degree descendants of patients with Alzheimer's disease (n = 55, group DAD) and participants without familial ancestry of the disease (n = 55, group NoDAD) were included. Incidental/intentional visuospatial memory was assessed, and the number of correct object-position associations was recorded to classify the participants by accuracy under incidental (4-8, high accuracy) and intentional (6-8, high accuracy) coding conditions. Comparisons with regard to between-group scores and frequency distribution were conducted. A mixed-model design analysis was employed to assess the impacts of the variables on accuracy. Results: DAD participants made fewer correct object-position associations than NoDAD under both incidental and intentional coding conditions. In addition, the percentage of NoDAD participants with a high accuracy in both incidental and intentional coding was higher (56.36%) than that for DAD participants (21.81%). A high percentage (36.364%) of DAD participants likewise showed a lower accuracy under both incidental and intentional coding conditions when compared to the NoDAD group (16.364%). Additionally, a marginally significant negative correlation between the number of correct object-position associations and age was found in DAD participants (r = -0.234, p = 0.054). Conclusions: The present results indicate an impairment in visuospatial incidental/intentional performance related to the familial history of AD, which was seen earlier (35-55 years old, mean age 43.12) in adulthood.