Chemotherapy and cognition: effects, potential mechanisms, and management

The development of novel chemotherapeutic agents and advances in treatment technique have improved survival for patients diagnosed with some forms of cancer, but treatments are not always site specific and may place normal tissues at risk. The central nervous system (CNS) is susceptible to treatment effects and complaints of memory loss and generalized cognitive decline are common among cancer patients. Despite the frequency of subjective patient complaints, studies evaluating the cognitive abilities of patients have inconsistently reported chemotherapy-related declines. On careful review of the literature, discrepant findings across studies (some documenting chemotherapy-related cognitive declines and others failing to detect such changes) may be attributed to differences in methodology. Most studies have been retrospective in design, omit pretreatment assessment of function, use small or heterogeneous samples, use inappropriate measures to assess cognition, and fail to incorporate control subjects. Though rare to date, prospective, randomized, longitudinal studies that incorporate pretreatment comprehensive neuropsychological assessment are necessary to define the severity and pattern of treatment-related change. Building on a foundation of solid science, future studies may identify subgroups of patients susceptible to significant chemotherapy-related cognitive decline. Once these groups are identified and the mechanisms underlying the decline are elucidated, attention may be turned to the development of treatments that may optimize cognitive function and improve patient quality of life.