Residual symptoms in depression an emerging therapeutic concept

Cushing's syndrome is due to chronic glucocorticoid excess that may have various etiologies. The most common endogenous form is pituitary-dependent bilateral adrenal hyperplasia, which is termed Cushing's disease. Major depression occurs in more than half of the cases. The presence of depressive symptoms connotes severity of clinical presentation and, in patients with hypothalamic-pituitary forms, entails prognostic value. Medical treatment may be used while awaiting more definitive solutions for the illness by surgery. The inhibitors of steroid production (e.g., ketoconazole, metyrapone and aminoglutethimide), rather than antidepressant drugs, are generally successful in lifting depression as well as other disabling symptoms. Since central serotonergic regulation could have a role in the course of Cushing's disease, serotonin antagonists (e.g., cyproheptadine, ritanserin and ketanserin) have been employed. Findings related to the pharmacological response of depression in Cushing's disease were found to have implications for the pathophysiology of depression and the potential involvement of the hypothalamic-pituitary-adrenal axis (HPA axis) in resistance and tolerance to antidepressant drugs. The use of serotonergic drugs in Cushing's disease may yield important insights in the understanding of serotonergic regulation both in Cushing's disease and in the HPA axis in nonendocrine major depression.

Psychiatric disorders associated with Cushing's syndrome. Epidemiology, pathophysiology and treatment

Cushing's syndrome is caused by a chronic excess of glucocorticoids. A number of psychiatric and psychological disturbances may be associated with the condition, regardless of its aetiology. Major depression is the most common comorbid disorder. Other psychopathological aspects of Cushing's syndrome in adults include mania, anxiety disorders and cognitive dysfunction. The presence of depression connotes a severe clinical presentation and, in patients with hypothalamic-pituitary forms of Cushing's syndrome, is prognostically useful. Inhibitors of corticosteroid production (e.g. ketoconazole, metyrapone, aminoglutethimide), rather than antidepressant drugs, are generally successful in relieving depressive symptoms, as well as other disabling symptoms. These drugs can be used to control symptoms prior to surgical treatment of Cushing's syndrome. Long-standing hypercortisolism may cause some degree of irreversible pathological damage and induce highly individualised affective responses based on each patient's psychological assets and liabilities. As a result, upon normalisation of cortisol levels, treatment may still be required, and should encompass both psychotherapeutic strategies (particularly cognitive-behavioural therapies that have been found to be effective in affective disorders) and psychotropic drug treatment [antidepressants such as tricyclic agents and selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors]. In patients with severe anxiety, benzodiazepines (e.g. clonazepam in small doses) may also be helpful.

Antiglucocorticoid drugs in the treatment of depression

A confluence of evidence indicates that prolonged elevation in gluco-corticoid level may result in disturbances of mood and cognition. In Cushing's syndrome, hypersecretion of cortisol is associated with a high incidence of depression, impairment in memory and hippocampal atrophy. Pharmacological usage of glucocorticoids is similarly productive of mood change and memory deficit. In patients with endogenous depression, hypercortisolaemia is associated with cognitive dysfunction and possibly a decrease in hippocampal volume. In each of these conditions, reduction of glucocorticoid level, either through discontinuation of steroid treatment or through usage of agents that block glucocorticoid synthesis, ameliorates the adverse behavioural effects. Traditional antidepressant agents may, in addition, stabilise mood through actions on the hypothalamic-pituitary adrenocortical (HPA) system. Although clinical usage of the currently available antiglucocorticoid drugs is limited by significant adverse side effect profiles, development of drugs specifically targeting the glucocorticoid receptor may lead to innovative strategies in the treatment of mood disorders.