COGNITION, STEROIDS AND IMAGING IN CUSHINGS DISEASE

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DESCRIPTION (Adapted from applicant's abstract): Dysregulation of the hypothalamic-pituitary-adrenal axis resulting in hypercortisolemia is present in a significant proportion of the aged and in neuropsychiatric conditions such as Alzheimer's Disease and Major Depressive Disorder. However, the relationship of this dysregulation to clinical symptoms is still insufficiently understood. Patients with CD exhibit hypercortisolemia and develop disturbances in mood, sleep, libido, and cognition. The investigator's hypothesis is that steroid elevations in these various conditions have important neuroactive effects. The investigator's objective is to examine the role of steroids in the pathophysiology of behavior by exploiting the fact that patients with CD are a unique model providing sustained exposure to high concentrations of endogenous steroids over a long-term period. The studies proposed focus on abnormalities in cognition. Studies in animals indicate that elevated corticosteroids result in toxicity to the hippocampus. This is one likely mechanism for the manner in which glucocorticoids elicit cognitive dysfunction. The investigator proposes to use MRI of the brain together with neuropsychologic (NP) testing to investigate such a mechanism in humans. Evidence is accumulating that other steroids such as androgens play key roles in modulating neuronal excitability. In many patients with CD, testosterone and dehydroepiandrosterone (DHEA) are also markedly elevated. The investigator's specific aims are to: 1) Study in fine detail cognitive dysfunction in patients with CD using sensitive, specific tests with graded levels of difficulty to probe for subtle as well as easily-elicited abnormalities. 2) Examine, prior to treatment, MRI-determined hippocampal formation (HF) volume in patients with CD, and compare to the volume of age, sex, and education-matched normal controls. The investigator will examine specificity for region by measuring and comparing the volumes of caudate head (CH), frontal lobe and anterior temporal lobe (ATL). 3) Examine associations between severity of hypercortisolemia, NP impairment and HF volume. The volumes of CH, frontal and ATL will be used as comparison regions. 4) Repeat NP testing and MRI one and two years following treatment of CD, in order to determine if changes in cognition and HF volume are reversible. Associations between changes in volume and cognitive test scores will be studied. 5) Examine the potential modulatory role of the androgens testosterone and DHEA, co-secreted with cortisol, on tests of attention, learning and memory. Hypercortisolemia occurs with aging and in several important neuropsychiatric diseases. The studies proposed will help advance knowledge about the role of the glucocorticoid cortisol in the mechanisms contributing to cognitive dysfunction in these conditions. The rationale for developing protective drugs such as site-specific glucocorticoid receptor antagonists or excitatory amino acid suppressors would be strengthened.