Neuropsychiatric disorders and cognitive dysfunction in patients with Cushing's disease.

Objective: To review the main neuropsychiatric disorders and cognitive deficits in patients with Cushing's disease (CD) and the associated pathophysiological mechanisms underlying CD. These mechanistic details may provide recommendations for preventing or treating the cognitive impairments and mood disorders in patients with CD.

Data Sources: Data were obtained from papers on psychiatric and cognitive complications in CD published in English within the last 20 years. To perform the PubMed literature search, the following keywords were input: cushing's disease, cognitive, hippocampal, or glucocorticoids.

Study Selection: Studies were selected if they contained data relevant to the topic addressed in the particular section. Because of the limited length of this article, we have frequently referenced recent reviews that contain a comprehensive amalgamation of literature rather than the actual source papers.

Results: Patients with active CD not only suffer from many characteristic clinical features, but also show some neuropsychiatric disorders and cognitive impairments. Among the psychiatric manifestations, the common ones are emotional instability, depressive disorder, anxious symptoms, impulsivity, and cognitive impairment. Irreversible effects of previous glucocorticoid (GC) excess on the central nervous system, such as hippocampal and the basal ganglia, is the most reasonable reason. Excess secretion of cortisol brings much structural and functional changes in hippocampal, such as changes in neurogenesis and morphology, signaling pathway, gene expression, and glutamate accumulation. Hippocampal volume loss can be found in most patients with CD, and decreased glucose utilization caused by GCs may lead to brain atrophy, neurogenesis impairment, inhibition of long-term potentiation, and decreased neurotrophic factors; these may also explain the mechanisms of GC-induced brain atrophy and hippocampal changes.

Conclusions: Brain atrophy and hippocampal changes caused by excess secretion of cortisol are thought to play a significant pathophysiological role in the etiology of changes in cognitive function and psychiatric disturbances. The exact mechanisms by which GCs induce hippocampal volume loss are not very clear till now. So, further investigations into the mechanisms by which GCs affect the brain and the effective coping strategy are essential.