This article considers the quantitative techniques currently in use in the evaluation of cognitive impairments associated with chemotherapy treatment for breast cancer. To illustrate differences among analytical approaches, all analyses were applied to baseline and posttreatment scores on neuropsychological tests obtained from Stages I and II breast cancer patients receiving either chemotherapy or hormonal therapy; a healthy control group with similar demographics to those of the treatment groups was also included. Conventional group analyses were compared with individual-based analyses (standardized regression-based and reliable change methods). Both univariate and multivariate techniques with and without covariates produced negligible effects. In contrast, results of the individual-based analyses identified a subset of participants in the chemotherapy group who experienced a severe decline in function on two or more tests. Differences between the control and treatment groups were greater than differences between the treatment groups alone. The standardized regression-based approach was more sensitive than the reliable change index in detecting chemotherapy and hormonal therapy subjects whose performance was different from baseline scores on two or more tests (roughly 80% vs. 50% of participants). From a clinical perspective, the degree of impairment determined on the basis of the individual-based methodologies could have a major impact on quality of life for those affected. On the whole, we argue that the standardized regression-based approach, allowing for the assessment of individual practice effects and evaluation of moderator variables, is the method of choice in this context.

There is a great deal of variability in the composition of neuropsychological test batteries used in the assessment of cancerrelated cognitive impairment (CRCI). Not only the development of a gold standard approach for CRCI assessment would allow for easier identification of women suffering from CRCI but it would also promote optimal care for survivors. As a first step towards the development of a valid and reliable unified test battery, the objective of this study was to verify whether the theoretical domains commonly used in CRCI assessment are statistically supported, before and after breast cancer treatment. Principal component analyses (PCA) were performed on the results from 23 neuropsychological tests grouped into eight conceptual domains. For baseline data, the Kaiser-Meyer-Olkin was .82 and Bartlett’s X2(253, N=95) = 949.48, P<0.001. A five-component solution explained 60.94% of the common variance. For the post-treatment data, the Kaiser-Meyer-Olkin was .83 and Bartlett’s X2(253, N=95) = 1007.21, P<0.001 and a five component solution explained 62.03% of the common variance. Although a visual comparison of the theoretical model with those determined via PCA indicated important overlap between conceptual domains and statistical components, significant dissimilarities were also observed.

Research on chemotherapy-induced cognitive impairment (the term ‘‘chemo-fog’’ is used by many investigators) supports the occurrence of subtle declines in function for a subset of recipients. Identification of vulnerable individuals via comprehensive neuropsychological batteries is complicated due to their lack of clinical utility and increased risk of misclassification. The goal of this paper was to evaluate the ability of a reduced battery to detect chemotherapy-related cognitive impairments. Data from our previous study (Ouimet et al. J Clin Exp Neuropsychol 31:73–89, 2009) were used to compare a comprehensive neuropsychological test battery comprising 23 tests with a reduced battery consisting of a subset of nine tests. A standardized regression-based approach revealed that a comparable numbers of participants were identified by both batteries, suggesting that individuals vulnerable to chemotherapy-induced cognitive impairment can be identified by a more selective battery. Further work is needed to clarify the neuropsychological tests most sensitive to detecting impairments associated with chemotherapy so that assessment batteries can be limited to these tests

Research on chemotherapy-induced cognitive impairment (the term ‘‘chemo-fog’’ is used by many investigators) supports the occurrence of subtle declines in function for a subset of recipients. Identification of vulnerable individuals via comprehensive neuropsychological batteries is complicated due to their lack of clinical utility and increased risk of misclassification. The goal of this paper was to evaluate the ability of a reduced battery to detect chemotherapy-related cognitive impairments. Data from our previous study (Ouimet et al. J Clin Exp Neuropsychol 31:73–89, 2009) were used to compare a comprehensive neuropsychological test battery comprising 23 tests with a reduced battery consisting of a subset of nine tests. A standardized regression-based approach revealed that a comparable numbers of participants were identified by both batteries, suggesting that individuals vulnerable to chemotherapy-induced cognitive impairment can be identified by a more selective battery. Further work is needed to clarify the neuropsychological tests most sensitive to detecting impairments associated with chemotherapy so that assessment batteries can be limited to these tests.

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