Cognitive impairment following chemotherapy for breast cancer: The impact of practice effect on results

Chemotherapy-Related Cognitive Impairment (CRCI) can be an adverse effect in women treated for breast cancer. Some longitudinal studies reported deficits in attention, memory, and executive function following treatment, but other studies did not find cognitive changes. It is known that practice effects (PE) on repeated assessments with cognitive tests contribute to the discrepancies in these results, but its influence on scores has not been systematically explored. The present study examines the impact of PE on retest scores in a group of women with breast cancer treated with chemotherapy and evaluated longitudinally. Method: 51 women with breast cancer treated with a combination of 5-fluorouracil, epirubicin, and cyclophosphamide with or without taxanes were assessed after surgery but before chemotherapy (T1), post-chemotherapy (T2), and at one year after T2 (T3). Longitudinal changes on cognitive performance were analyzed twice: when retest scores were not corrected for PE and when correction for PE was applied to T2 and T3 scores. Results: When PE was not corrected, progressive improvement over time in measures of memory and divided attention at T2 and T3 was observed. In contrast, when PE was corrected, worsening was found in measures of memory, fluency, executive function, and attention at T2 and in attention and executive function at T3. Results after correction for PE are in line with previous longitudinal studies that report cognitive impairment after treatment with chemotherapy for breast cancer. Conclusion: Accounting for PE is recommended to identify true change on cognition through treatment with chemotherapy for breast cancer.