Subclinical Cushing's syndrome is a potential cause of metabolic dementia and rapidly progressive Alzheimer-type dementia.

Excess of glucocorticoid hormones are found to exert deleterious effects on the structure and function of central nervous system, especially the hippocampus. This is manifested as mental and mood changes in Cushing syndrome. Subclinical Cushing's syndrome (SCS) is much more prevalent than Cushing's syndrome, and presents with increased plasma cortisol levels, but lack of the cardinal manifestations of Cushing's syndrome. In dementia, the impairment of hypothalamic-pituitary-adrenal axis has been shown, and hypercortisolism has been accused for rapidly progressive cognitive decline in Alzheimer disease. We hypothesized that SCS may cause metabolic dementia, and should be searched in case of rapidly progressive dementia of Alzheimer type.