A Quantitative Analysis of Cognitive Impairments Following Breast Cancer Treatment

Abstract

One in nine North American women will be diagnosed with breast cancer in their lifetime and most will receive chemotherapy as part of their treatment. Although advances in treatment have increased survivorship, some research suggests chemotherapy results in cognitive deficits in a subset of recipients, a condition known as chemo-fog, thereby compromising quality of life. However, inconsistencies in methodology and neuropsychological assessment have complicated comparison of findings. The first objective of this thesis was to review the methodological issues with an emphasis on the quantitative techniques typically employed. A comparison of group and individual based analyses found negligible effects for both univariate and multivariate approaches while individual based analyses identified severe declines in function in a subset of participants. A standardized-regression based (SRB) approach was recommended as the method of choice. Furthermore, it was recommended that the number of tests be limited since comprehensive batteries can complicate identification due to increased risk of misclassification. Therefore, the second goal of the thesis was to evaluate the sensitivity of a reduced battery to the declines associated with chemo-fog. A comprehensive neuropsychological battery comprising 23 tests was compared to a subset of nine tests. SRB analyses demonstrated that a more selective battery was equally useful and may be appropriate for identification of chemo-fog. Given the variability in the composition of neuropsychological test batteries, the final aim of this thesis was to compare the structure of the theoretical cognitive domains with ones identified through exploratory factor analyses (principle axis factoring) to evaluate the convergence between the two. The results demonstrated there is statistical support for the conceptual framework that underlies the composition of the domains. The contributions of this thesis include providing methodological guidelines for those conducting future research in this area to ensure that results are comparable across studies and are meaningful, and evaluating the utility of a screening battery to facilitate identification of chemo-fog. In addition, it was demonstrated that despite the lack of professional guidelines informing the selection and construction of neuropsychological test batteries, there is statistical evidence to support the practice of grouping tests into domains based on theoretical grounds.