Are dexamethasone suppression test nonsuppression and thyroid dysfunction related to a family history of dementia in patients with major depression? An exploratory study

Objective: Recent data suggest that the low thyroid function syndrome in depression is nonspecific. They also suggest that depression may constitute a risk factor for the development of dementia, especially in atypical patients who have high rates of hypothalamo-pituitary-adrenal axis disorders. This study aimed to search for correlations among Dexamethasone Suppression Test (DST) cortisol levels, thyroid indices, and family history of dementia in patients with depression. Methods: A sample of 30 patients, aged 21 to 60 years and suffering from major depression according to DSM-IV criteria, took part in the study. Three had a family history of dementia in first-degree relatives. We measured their serum levels of free T3, free T4, thyroid-stimulating hormone, thyroid binding inhibitory immunoglobulines, thyroglobulin antibodies, and thyroid microsomal antibodies (TMAs). We applied the 1-mg DST to all patients. The statistical analysis included 1-way multivariate analysis of covariance using t tests as the post hoc tests. Results: Significantly higher levels of TMAs were found in patients with a family history of dementia, compared with those who did not have this family history. Conclusion: The results of this study suggest that a more pronounced autoimmune process may characterize depression patients with a family history of dementia.