Dopamine Function and Hypothalamic-Pituitary-Thyroid Axis Activity in Major Depressed Patients with Suicidal Behavior

Area of Science:

• Neuroendocrinology
• Psychiatry
• Molecular Biology

Background:

• The roles of dopaminergic (DA) and hypothalamic-pituitary-thyroid (HPT) systems in suicidal behavior are not fully understood.
• Major depressive disorder (MDD) with suicidal behavior disorder (SBD) presents complex neuroendocrine challenges.

Purpose of the Study:

• To investigate the involvement of DA and HPT systems in suicidal behavior.
• To compare hormonal responses to apomorphine and thyrotropin-releasing hormone (TRH) challenges in patients with SBD and healthy controls.

Main Methods:

• Assessed multihormonal responses to apomorphine (DA receptor agonist) and TRH tests.
• Studied 30 medication-free DSM-5 euthyroid major depressed inpatients with SBD (current or in remission) and 18 healthy controls (HCs).
• Measured growth hormone (GH), adrenocorticotropin (ACTH), and thyrotropin (TSH) levels.

Main Results:

• Current SBD patients showed increased apomorphine-induced GH and ACTH, and reduced 11 PM TSH and ∆∆TSH compared to HCs.
• SBD patients in early remission had unaltered responses compared to HCs.
• An association between high apomorphine-GH and low ∆∆TSH was more frequent in recent suicide attempters.

Conclusions:

• Co-occurring alterations in DA and HPT systems may contribute to suicidal behavior pathophysiology.
• Normalization of DA and TRH functions may indicate recovery from suicidality.
• Targeting DAergic and TRH systems could be relevant for suicide prevention strategies.