We read with great interest the manuscript of van Beek et al.1 in which the authors report on the impact of radiotherapy on long-term health-related quality of life (HRQOL) and cognitive problems among patients treated for nonfunctioning pituitary adenoma (NFA). Following treatment, HRQOL, depression, fatigue, and cognitive functioning of irradiated and unirradiated patients was assessed using self-report questionnaires. Patients with or without RT attained comparable HRQOL scores in most domains and RT was even significantly associated with improved HRQOL in a multivariate model. No differences in cognitive function scores were observed.
Although we think that studies into the cognitive effects of treatment of these patients should be strongly encouraged, we would at the same time like to caution against the use of self-report questionnaires as a means to measure cognitive functioning.
Numerous studies that focus on perceptions of cognitive functioning have consistently found these self-reports to be unrelated to objective performance in distinct patient groups, including those with cancer2, coronary artery bypass surgery3,4, multiple sclerosis5,6, temporal lobe epilepsy surgery7, and HIV8. In cancer patients, and potentially also in those with pituitary adenomas, cognitive complaints might more likely reflect feelings of anxiety, depression and fatigue than a loss of cognitive abilities2. Considering the elevated levels of depression and fatigue in the study of van Beek and colleagues, this is most likely also the case in patients with NFA. We suggest these findings strongly argue against relying on patient reports to assess cognitive function. Objective testing remains the method of choice for assessing higher cognitive functions.