Impact of growth hormone-secreting pituitary adenoma on limbic system and its correlation with cognitive impairment

To assess the quantitative gray matter volume of the limbic system in growth hormone-secreting pituitary adenoma (GHPAs) patients and its correlation to cognitive function.

91 right-handed patients with pituitary adenomas were retrospectively included from the First Affiliated Hospital of Sun Yat-sen University -48 with GHPAs and 43 with non-functioning pituitary adenomas (NFPAs). Participants underwent serum hormone assessment, regular sellar MRI scanning with T1WI-MPRAGE. Cognitive function was gauged using MoCA and MMSE. Brain region auto-segmentation and gray matter volume calculation were conducted on the Brainsite platform.

Compared to NFPAs patients, GHPAs patients had higher gray matter volume (758,285 vs 674,610 mm³, p < 0.001). No significant volumetric differences in both sides of limbic system gray matter while there were evident differences in the relative volumes of limbic system gray matter between groups. GHPAs patients scored lower on MOCA (24.0 (2.18) vs 25.1 (2.28), p < 0.031), with no difference in MMSE. We observed a significant correlation between the relative limbic volume and MOCA scales, while no evident correlation was found between relative limbic volume and serum hormone or tumor aggressiveness. Univariate and multivariate Logistic regression showed that hippocampus and limbic cortex (parahippocampal gyrus and internal olfactory area) of advantageous hemisphere correlated significantly with occurrence of mild cognitive impairment with the C-statistic reaching 0.90.

Patients with GHPAs show a relative decrease in limbic gray matter volume, especially in the hippocampus and limbic cortex of the dominant hemisphere, which is associated with mild cognitive impairment.