A Cross-Sectional Study to Investigate Long-Term Cognitive Function in People with Treated Pituitary Cushing's Disease

Abstract

It has been proposed that exposure to high levels of endogenous steroids in untreated pituitary Cushing's disease damages hippocampal structures leading to impairment in learning and memory processes. We hypothesised that patients with treated pituitary Cushing's disease would perform significantly worse on tests of cognitive ability than those with nonfunctioning pituitary adenomas. Sixteen adults with pituitary Cushing's disease (PCD) and 16 adults with non-functioning pituitary adenomas (NFA) undertook the following comprehensive neuropsychological assessments: National Adult Reading Test (NART: premorbid abilities), California Verbal Learning Test (CVLT 2 UK: learning and recall), Stroop (executive functioning), Trail-Making Test (TMT: executive functioning and attention), Adult Memory and Information Processing Battery (AMIPB: Information Processing Speed and Story Recall subtests). There was no significant difference in premorbid IQ scores (NFA mean=101 SD=13; PCD mean=102, SD=13), in verbal learning nor any significant difference in the percentage of verbal material retained in story recall (AMIPB). Performance on higher executive tasks Stroop and TMT and on measures of information processing was similar. However, there were significant decrements between some mean scores for both groups and published normative data with a clear association between higher HADS depression scores and impaired objective memory and attention which was not specific to PCD. We found no difference in cognitive function between patients with PCD and NFA. The results suggest a discrepancy between patients' subjective perception of functional cognitive impairments and objective findings on psychometric testing and point to the influence of affective symptoms on cognitive performance, particularly in Cushing's disease.