OBJECTIVE: Cognitive impairment negatively affects some cancer survivors who have completed chemotherapy; however, factors underlying this cognitive impairment remain poorly understood. We aimed to investigate (1) the relative importance of demographics, medical, and psychological characteristics associated with cognitive impairment and (2) the specific variables associated with cognitive impairment in adult cancer survivors who completed adjuvant chemotherapy.
METHODS: We performed post hoc analyses of baseline data from early-stage cancer survivors with cognitive complaints who received adjuvant chemotherapy 0.5-5 years earlier and volunteered for a trial designed to improve cognition. The primary outcome of self-reported cognitive impairment was measured using a questionnaire; secondary outcome of objective cognitive impairment was measured using a computerized neuropsychological test battery. Hierarchical linear regression determined the relative importance of demographics, medical, and psychological characteristics in associations with both self-reported and objective cognitive impairment.
RESULTS: The sample was 95% female and 89% breast cancer patients. The final model accounted for 33% of variation in self-reported cognitive impairment (n = 212, demographics 5%, medical 3%, and psychological 25%), with fatigue and stress as significant individual correlates (p values <= 0.0001). For the secondary analysis, the final model accounted for 19% of variation in objective cognitive impairment (n = 206, demographics 10%, medical 5%, and psychological 4%), with age, smoking history, and number of chemotherapy cycles as significant individual correlates.
CONCLUSION: We found that psychological characteristics are more important than demographic and medical characteristics in self-reported cognitive impairment, whereas other characteristics are more important in objective cognitive impairment. This suggests clinicians should investigate possible psychological problems in cancer survivors who self-report cognitive impairment.