Emotion Induced Monoamine Neuromodulator Release Affects Functional Neurological Disorders

Abstract

Functional neurologic disorders (FNDs), also called conversion disorder (previously called hysteria), can show almost all the symptoms of other neurological diseases, including both physical (for example, seizure, weakness, fatigue) and psychological (for instance, depression, anxiety) symptoms. In spite of our general knowledge about emotional processes and developmental defects in the formation of these somatic symptoms, there is still no systemic and comprehensive research on the effects of emotional developmental variables in FND. Recently, both experimental and theoretical emotion studies have been greatly increased, such as prediction error, conceptual act model, basic emotional theory, and monoamine neuromodulator based three primary emotions. In addition, a large amount of evidence has confirmed the role of psychosocial adversity (such as stressful life events, interpersonal difficulties) as an important risk factor for FND. Here, we review recent advances about emotional stress on FND, and pay special attention to the effects of monoamine neuromodulators, such as how norepinephrine and serotonin affect behaviors. Then, we discuss the significance of these changes for FND, which may contribute to clarifying the pathogenesis of FND, and thus provide potential therapeutic drug targets or psychological intervention methods in the future.

Neurotransmitters and Electrophysiological Changes Might Work as Biomarkers for Diagnosing Affective Disorders

“…For example, major depressive disorders have major problems in the monoaminergic neuromodulators, and drug addictions have problems in dopaminergic problems. Just like what we proposed in our previous paper [ 3 ], almost all emotional disorders might be derived from the monoaminergic neuromodulators, and the first-line treatment for these diseases is still targeting monoaminergic neuromodulators. In addition, the levels of monoaminergic neuromodulators and event-related potentials can be used for the diagnosis for these diseases.…”

“…Diagnosis of affective disorders is getting even harder now, and we have probed into the ways in the diagnosis previously [ 1 , 3 , 14 , 25 ]. A better way to screen the affective disorder is using basic emotional theory [ 44 , 45 ].…”

“…Affective disorders are the leading causes of disability worldwide; for example, major depressive disorders are affecting more than 17% of the general population [ 1 ]. The neural mechanisms of the affective disorders (such as depression, anxiety, and functional neurological disorders) are yet to be uncovered [ 2 , 3 ]. The best way to study the affective disorders is through the basic emotional theory, which suggested that basic emotions are due to monoamines and peptides [ 4 , 5 ].…”

The Aversion Function of the Limbic Dopaminergic Neurons and Their Roles in Functional Neurological Disorders

“…FND patients tend to be more negative at loss and gain lower feelings of happiness from reward than healthy people. Consequently, they feel exhausted, indifferent, and even depressed, which appears to be consistent with symptoms of lacking DA (Logan and McClung, 2019;Xia et al, 2019;Liang et al, 2021). In conclusion, it is necessary to further explore the activation difference of DAergic neurons between FND patients and healthy people with predicting reward or aversion, so as to uncover the causes for FND.…”

“…Psychological disorders and stressful life events, both recent and in childhood, may be risk factors for developing the condition in some patients, but they rarely provide a full explanation for the cause of the condition and are absent in many patients. Modern theories propose that FND has many causes, especially the monoamine neurotransmitters ( Liang et al, 2021 ).…”