Mild cognitive impairment in long-term brain tumor survivors following brain irradiation

There is no accepted classification of cognitive impairment in cancer survivors. We assess the extent of mild cognitive impairment (MCI) syndrome in brain tumor survivors using criteria adapted from the National Institute on Aging and the Alzheimer's Association (NIA-AA).

We retrospectively reviewed the cognitive data of brain tumor survivors post-radiation therapy (RT) enrolled from 2008 to 2011 in a randomized trial of donepezil versus placebo for cognitive impairment. One hundred and ninety eight adult survivors with primary or metastatic brain tumors who were ≥ 6 months post RT were recruited at 24 sites in the United States. Cognitive function was assessed at baseline, 12 and 24 weeks post-randomization. For this analysis, we used baseline data to identify MCI and possible dementia using adapted NIA-AA criteria. Cases were subtyped into four groups: amnestic MCI-single domain (aMCI-sd), amnestic MCI-multiple domain (aMCI-md), non-amnestic MCI-single domain (naMCI-sd), and non-amnestic MCI-multiple domain (naMCI-md).

One hundred and thirty one of 197 evaluable patients (66%) met criteria for MCI. Of these, 13% were classified as aMCI-sd, 58% as aMCI-md, 19% as naMCI-sd, and 10% as naMCI-md. Patients with poorer performance status, less education, lower household income and those not working outside the home were more likely to be classified as MCI.

Two-thirds of post-RT brain tumor survivors met NIA-AA criteria for MCI. This taxonomy may be useful when applied to brain tumor survivors because it defines cognitive phenotypes that may be differentially associated with course, treatment response, and risk factor profiles.