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Noradrenaline plays a critical role in the switch to a manic episode and treatment of a depressive episode

View Article: PubMed Central - PubMed

ABSTRACT

Although antidepressants may increase the risk of switching to mania in bipolar disorder (BD), clinicians have been using antidepressants to treat patients with bipolar depression. Appropriate treatments for bipolar depression remain controversial. In BD, antidepressants comprise a double-edged sword in terms of their efficacy in treating depression and the increased risk of switching. This review presents an important table outlining the benefit in terms of depression improvement and the risk of switching in the clinical setting. It also proposes strategies based on the characteristics of antidepressants such as their pharmacology, specifically the equilibrium dissociation constant (KD) of the noradrenaline transporter. This table will be useful for clinicians while considering benefit and risk. Antidepressants augmenting noradrenaline may be effective in bipolar depression. However, it is easily presumed that such antidepressants may also have a risk of switching to mania. Therefore, antidepressants augmenting noradrenaline will be the recommended treatment in combination with an antimanic agent, or they may be used for short-term treatment and early discontinuation. The corresponding medical treatment guidelines probably need to be reevaluated and updated based on biological backgrounds. From previous studies, we understand that the stability of noradrenaline levels is important for BD amelioration, based on the pathophysiology of the disorder. It is hoped that researchers will reevaluate BD by conducting studies involving noradrenaline.

No MeSH data available.


Schematic illustration showing the improvement or switching pathways induced by various antidepressants affecting the levels of noradrenaline.Notes: Augmentation of noradrenaline as various antidepressants can be the result of the three actions: (A) noradrenaline reuptake inhibitory action, (B) inhibitory action of noradrenaline deactivation, and (C) α2-autoreceptor inhibitory action.
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f1-ndt-12-2373: Schematic illustration showing the improvement or switching pathways induced by various antidepressants affecting the levels of noradrenaline.Notes: Augmentation of noradrenaline as various antidepressants can be the result of the three actions: (A) noradrenaline reuptake inhibitory action, (B) inhibitory action of noradrenaline deactivation, and (C) α2-autoreceptor inhibitory action.

Mentions: The urinary concentrations of noradrenaline and its metabolite MHPG were significantly lower in depression than in mania.23 Although HVA, a dopamine metabolite, did not differ, MHPG, a noradrenaline metabolite, was greater in untreated BD patients than in healthy controls.38 Recently, it was reported that MHPG is a biomarker for the switch from the manic state to the remission state in BD.28 The study suggested that the effects of antipsychotics were slight with reference to chlorpromazine equivalence (average: 134 mg/d). In addition, in multiple regression analyses, the plasma levels of MHPG reflected the pathophysiology of BD from the manic state to the depressive state more clearly than did plasma HVA or brain-derived neurotrophic factor (BDNF).9 Thus, noradrenaline may be involved in the pathophysiology of BD (Figure 1).


Noradrenaline plays a critical role in the switch to a manic episode and treatment of a depressive episode
Schematic illustration showing the improvement or switching pathways induced by various antidepressants affecting the levels of noradrenaline.Notes: Augmentation of noradrenaline as various antidepressants can be the result of the three actions: (A) noradrenaline reuptake inhibitory action, (B) inhibitory action of noradrenaline deactivation, and (C) α2-autoreceptor inhibitory action.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036557&req=5

f1-ndt-12-2373: Schematic illustration showing the improvement or switching pathways induced by various antidepressants affecting the levels of noradrenaline.Notes: Augmentation of noradrenaline as various antidepressants can be the result of the three actions: (A) noradrenaline reuptake inhibitory action, (B) inhibitory action of noradrenaline deactivation, and (C) α2-autoreceptor inhibitory action.
Mentions: The urinary concentrations of noradrenaline and its metabolite MHPG were significantly lower in depression than in mania.23 Although HVA, a dopamine metabolite, did not differ, MHPG, a noradrenaline metabolite, was greater in untreated BD patients than in healthy controls.38 Recently, it was reported that MHPG is a biomarker for the switch from the manic state to the remission state in BD.28 The study suggested that the effects of antipsychotics were slight with reference to chlorpromazine equivalence (average: 134 mg/d). In addition, in multiple regression analyses, the plasma levels of MHPG reflected the pathophysiology of BD from the manic state to the depressive state more clearly than did plasma HVA or brain-derived neurotrophic factor (BDNF).9 Thus, noradrenaline may be involved in the pathophysiology of BD (Figure 1).

View Article: PubMed Central - PubMed

ABSTRACT

Although antidepressants may increase the risk of switching to mania in bipolar disorder (BD), clinicians have been using antidepressants to treat patients with bipolar depression. Appropriate treatments for bipolar depression remain controversial. In BD, antidepressants comprise a double-edged sword in terms of their efficacy in treating depression and the increased risk of switching. This review presents an important table outlining the benefit in terms of depression improvement and the risk of switching in the clinical setting. It also proposes strategies based on the characteristics of antidepressants such as their pharmacology, specifically the equilibrium dissociation constant (KD) of the noradrenaline transporter. This table will be useful for clinicians while considering benefit and risk. Antidepressants augmenting noradrenaline may be effective in bipolar depression. However, it is easily presumed that such antidepressants may also have a risk of switching to mania. Therefore, antidepressants augmenting noradrenaline will be the recommended treatment in combination with an antimanic agent, or they may be used for short-term treatment and early discontinuation. The corresponding medical treatment guidelines probably need to be reevaluated and updated based on biological backgrounds. From previous studies, we understand that the stability of noradrenaline levels is important for BD amelioration, based on the pathophysiology of the disorder. It is hoped that researchers will reevaluate BD by conducting studies involving noradrenaline.

No MeSH data available.