Mast cell activation can induce neuropsychiatric symptoms. Degranulation has been linked previously to headache. It is possible that peptidergic and cholinergic neurons receive mast cell mediators and that this plays a role in headache pathology. TNF is speculated to participate in depression. Histamine may cause memory deficits, although there is conflicting information on this topic. Some patients have improvement in neuropsychiatric symptoms with antihistamines.
Mastocytosis patients who have GI and neuropsychiatric symptoms often have low serum serotonin. Tryptophan is a precursor to serotonin. Plasma tryptophan is also often low in mastocytosis patients, while plasma IDO1 (indoleamine-2,3-dioxygenase 1) activity is higher. IDO1 breaks down tryptophan through an alternate pathway that does not form serotonin. In this pathway, IDO1 breaks down tryptophan, forming kynurenic acid and quinolinic acid. The accumulation of these substances could explain the fatigue and cognitive impairment in mastocytosis patients. Low tryptophan and low serotonin in this population were associated with perceived stress and depression.
Treatment of neuropsychiatric symptoms in mast cell patients can include a variety of medications. SSRI medications can reduce fatigue and depression in some inflammation models. Some mast cell patients take these medications, usually with low starting doses in case mast cell degranulation in these people has conversely led to higher serotonin levels. Bupropion, SNRIs and tricyclic medications are also commonly used for depressive symptoms in many chronic illness populations.
Some tricyclic antidepressants have antihistamine properties, with doxepin being a common choice. Another tricyclic, amitriptyline, can inhibit release of mast cell mediators. Mianserin and mirtazapine can be prescribed for insomnia but also have antihistamine properties. Aprepitant could potentially be used in treatment of depression and cognitive impairment in mastocytosis and MCAS patients. Prochloperazine also decreases mast cell mediator release. Amantadine has improved depression and fatigue symptoms in multiple sclerosis patients. Inhibition of TNF with infliximab has improved depression in patients with high levels of inflammation.
Kynurenic acid, formed in the alternate tryptophan breakdown pathway described above, can block acetylcholine receptors, causing neurologic symptoms. A7 agonists like nicotine could potentially overcome this effect. Quinolinic acid binds at the NMDA receptor, cause neurologic symptoms. Ketamine, an NMDA antagonist, can produce significant improvements in depressive symptoms in treatment resistant depression. As quinolinic acid is typically present in higher levels than kynurenic acid in mastocytosis patients, ketamine might offer a treatment for these patients with depression and high perceived stress.
Masitinib, a tyrosine kinase inhibitor, was shown to decrease depression, anxiety and cognitive difficulties in a significant amount of mastocytosis patients. Mindful meditation may also help patients to lessen activation caused by psychological stress and therefore decreasing biological stress.
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