The Effects of Radiation to the Hippocampus and Subventricular Zone on Verbal Memory and Executive Function

Abstract

As cancer treatments improve survival time for patients with brain tumors, increased importance has been placed on maintaining quality of life for longer periods of time. Cognition is an important aspect of quality of life that can be affected both by tumor effects as well as treatment-related effects. Research has recently begun to investigate interventions for reducing these effects, particularly with radiation, as it typically used to treat these patients. In an effort to reduce radiation treatment-related effects, radiation treatment planning can be contoured to avoid various structures known to be especially sensitive to the effects of radiation or those structures central to various cognitive processes. Given the growing tendency to avoid structures of special import during radiation therapy, the present study investigated the role of radiation dose to the hippocampus in changes in verbal memory and likewise the role of radiation dose to the subventricular zone (SVZ) in changes in executive function. Radiation to the hippocampus was found to be related to various indices of verbal memory. Radiation to the subventricular zone was related to learning acquisition, the rate at which a list of words was learned. Radiation to the left hippocampus was not related to any indices of executive functioning. A relationship was observed between radiation to the SVZ and one index of executive functioning. Implications, limitations, and future directions are discussed.