Modeling memory impairments in cancer survivors: Impaired retrieval processes

Cognitive impairment is an often-overlooked issue that cancer survivors face, with a third of non-CNS cancer survivors reporting memory problems. Memory, however, is complex and consists of various underlying cognitive processes. The objective of this research is to investigate memory problems more thoroughly in cancer patients. This was done through an adapted Hierarchical Bayesian cognitive model from the Alzheimer’s Disease literature, which splits memory into several processes relating to either learning or retrieving words from any of three memory states (unlearned, partially learned, learned). Participants were cancer survivors (n=187) of various non-CNS tumors (breast, prostate, and others) who received various cancer treatments (chemo-, endocrine-, radio- and immunotherapy) and no-cancer controls (n=204). The participants completed the Amsterdam Cognition Scan (ACS), in which classical neuropsychological tests are digitally recreated for online at-home administration. The specific test used to investigate verbal memory was the ACS equivalent of a Verbal Learning Test, in which participants are tasked with recalling a list of 15 words five times. Later in the test battery the participant is asked to recall these 15 words again, as a delayed recall trial. A traditional analysis of the sum of trials 1-5 indicated a small effect size difference between patients and controls, t(385.23)=2.81, p <.01, d=.28. There was no significant difference between patients and controls in the delayed recall trial. For the underlying memory processes, significant differences were found in the immediate retrieval process parameters, both retrieval from a partially learned state (t(378.47)=2.6, p <.01, d = .26) and retrieval from a learned state (t(381.57)=2.44, p =.02, d = .25). No differences were found in any parameters related to learning processes, nor in the delayed retrieval process parameter. The results indicate that the memory problems in cancer survivors are likely due to selective impairment of memory retrieval processes, rather than through learning impairment or a general impairment.