title: Input and output order of recall as early markers of cognitive decline
Creators: name: Talamonti, D
Publisher: name: Liverpool John Moores University
Year: 2019

description: This thesis explored the effects of age on free recall patterns in episodic memory. Neuropsychological and neuroimaging instruments were used to investigate the input (i.e., serial position effects) and output (i.e., temporal vs. spatial contiguity) of free recall in younger vs. healthy older individuals and in older adults with cognitive decline. In study 1 (Chapter 4), primacy (intended as the tendency to better remember items presented at the beginning of a list compared to the middle) at delayed recall was the most accurate serial position effect in predicting conversion to early stage Mild Cognitive Impairment (MCI), from a baseline of cognitively functioning older adults. In study 2 (Chapter 5), age differences in the use of spatial vs. temporal contiguity (intended as the tendency to retrieve items following the temporal, or spatial, context in which they have been learned) were explored in younger vs. healthy older adults. It was found that temporal contiguity was the most utilised associative process in both groups, although older adults showed lower temporal contiguity compared to younger adults. In study 3 (Chapter 6), the universality of temporal contiguity and the relationship between attentional processes and the output order of free recall were examined. Temporal vs. spatial contiguity were investigated during tasks meant to interfere with encoding processes, that is Divided Attention (DA) tasks and tasks involving presentation of verbal vs. pictorial material. Results showed consistent use of temporal contiguity in all experimental conditions, therefore suggesting the ubiquity of temporal contiguity and its involvement in retrieval processes. In study 4 (Chapter 7), the output order in free recall was investigated in younger and older adults in relation to prefrontal blood oxygenation, by means of functional Near-Infrared Spectroscopy (fNIRS). It was found that areas involved during temporal contiguity change with age, as younger adults showed greater activity of the right prefrontal cortex, whilst older adults engaged alternative or opposite regions. In study 5 (Chapter 8) the use of unrelated memory lists was investigated as a sensitive measure to detect age-related differences on the use of temporal vs. spatial contiguity. Moreover, age-associated differences in the use of temporal contiguity were explored at immediate vs. delayed recall. It was found that unrelated lists are able to detect age-related changes in the use of contiguity effects, and that temporal contiguity is negatively affected in both younger and older adults at delayed recall. In study 6 (Chapter 9) temporal clustering was investigated as potential predictor of conversion to Cognitive Unimpaired Declining (CUD) status, from a baseline of cognitively functioning older individuals. Results supported the hypothesis that temporal contiguity is a marker of cognitive decline, also when controlling for genetic information and for variables typically used in clinical practice. In summary, the findings of this thesis show that the input and output order of free recall, although quite stable, decline with age and that they may be added as a potential tool for early detection in clinical settings, and in the research field.