Improvement in learning associated with increase in hippocampal formation volume

Biol Psychiatry. 2003 Feb 1;53(3):233-8. doi: 10.1016/s0006-3223(02)01750-x.


Background: Patients with spontaneous Cushing's syndrome are exposed to elevated levels of endogenous cortisol for months to years. We previously reported that hippocampal formation volume (HFV) increased in such patients after treatment lowered cortisol to normal concentrations. In the present study, we examined whether the structural increase was associated with improvement in cognition.

Methods: Twenty-four patients with Cushing's disease were studied before treatment and following treatment. Magnetic resonance imaging was used to measure HFV and caudate head volume. Neuropsychologic tests of verbal cognition, learning, and memory were also administered.

Results: Patients showed variability in improvement on neuropsychologic test performance. After partialing out age, education, duration of illness, and time since surgical treatment, greater improvement in word list learning, as measured by the Selective Reminding Test was associated with greater increase in HFV (r =.59, p <.02). There were no significant associations between improvement in paragraph or paired-word learning or memory tasks and increase in HFV. Improvement in other verbal tasks not strongly dependent on the hippocampus were not significantly associated with increase in HFV.

Conclusions: After cortisol levels decline to normal concentrations, structural volumetric increase in HFV is accompanied by functional improvement in learning of unrelated words.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoma / diagnosis
  • Adenoma / pathology
  • Adenoma / psychology
  • Adenoma / surgery
  • Adult
  • Caudate Nucleus / pathology
  • Cushing Syndrome / diagnosis*
  • Cushing Syndrome / pathology
  • Cushing Syndrome / psychology
  • Cushing Syndrome / surgery
  • Endoscopy
  • Female
  • Follow-Up Studies
  • Hippocampus / pathology*
  • Humans
  • Hydrocortisone / blood*
  • Hypophysectomy
  • Logic
  • Magnetic Resonance Imaging*
  • Male
  • Mental Recall / physiology*
  • Middle Aged
  • Neuropsychological Tests*
  • Paired-Associate Learning / physiology
  • Pituitary Neoplasms / diagnosis
  • Pituitary Neoplasms / pathology
  • Pituitary Neoplasms / psychology
  • Pituitary Neoplasms / surgery
  • Postoperative Complications / diagnosis
  • Postoperative Complications / pathology
  • Postoperative Complications / surgery
  • Problem Solving / physiology
  • Verbal Learning / physiology*


  • Hydrocortisone