Endocrine Abstracts

Background: Studies of memory function in patients treated for pituitary adenoma demonstrate deficits in immediate memory (IM) regardless of whether surgery or radiotherapy was received. We have previously shown variability in IM between patients who received the same treatment. The present study was designed to identify changes in the neurological pathways associated with memory function in patients treated for non-functioning pituitary adenoma (NFA) using functional magnetic resonance imaging (fMRI).

Method: Six patients treated for NFA, were selected from a cohort of patients who had undergone psychometric assessment. They were similar in pituitary function, hormone replacement and age. Three had normal IM and three had impaired IM. Patients performed an IM task, which assessed content (the stimuli themtselves) and context (when the stimuli occurred) of memory for novel and familiar non-words. These tasks were performed inside an MRI scanner (LREC approved).

Results: The impaired group (IG) demonstrated worse performance than the control group (CG) on the measure of content memory (P=0.026). When the between groups analysis was conducted with a cluster threshold of z=1.5, P<0.05 (z=x standard deviations of the mean above the CG; larger z indicates more power), the following areas were significantly more active in the IG group: parahippocampal cortex, z=2.46; anterior cingulate, z=2.72, and frontal pole, z=2.57. Although performance across groups was similar in the measure of context memory, the IG showed far greater thalamic activity, z=4.11.

Conclusions: This study has demonstrated that the functional pathway involved in memory in patients treated for NFA is abnormal in those with impaired memory compared to those with normal memory. These data shed light on potentially important physiological mechanisms that may account for some of the negative neurocognitive consequences of NFAs and their treatment.