Religion and Spirituality in Psychiatry

Religion/Spirituality and Neuropsychiatry 49are distributed widely in the brain and coverspecific regions. They are synthesized in thepre-synaptic neuron and are released from thisneuron into the synaptic gap to act on a specificneurotransmitter receptor. They can bindonly to this specific receptor, and their effect isdetermined by this receptor. Several types ofneurotransmitters cause either excitement orinhibitory impulses. For example, glutamate isthe most important excitatory neurotransmitterin the brain, whereas gamma-aminobutyricacid (GABA) and glycine are inhibitory ones.However, we will focus on serotonin and dopamine,because they are the most investigated ofthe neurotransmitters in our subject area. Theycover the brain activities of both those whoare involved in religious practices and thoseinvolved in spiritual activities.5-HT are located in the brainstem in an areacalled the raphe nuclei. Their axons project inmany areas of the brain, notably the cerebralcortex, hypothalamus, limbic system, and thestriatum. These neurons modulate the activityof several brain regions by their inhibitory orexcitatory action on brain receptor subtypes. Inaddition, 5-HT is believed to play an importantrole in several psychiatric conditions includingdepressive disorders, anxiety disorders, suicidalbehaviors, aggression and anger-related traits,and even schizophrenia and similar disorders.Particularly, low levels of 5-HT have been associatedwith aggression, violent behavior, suicidaltendency, and clinical depression in humanstudies. As we will discuss below, 5-HT has alsobeen directly implicated in meditation and religiousexperiences.2.1. Serotonin or 5-hydroxytryptamine(5-HT)If both sympathetic (norepinephrine, adrenaline)and parasympathetic (acetylcholine)systems have been shown to be stimulated inmeditation and other related experiences (seebelow), serotonin (5-HT) and to a lesser degreedopamine have been the focus of geneticistsand neuroscientists. The involvement of the5-HT system in spiritual-like experiences issupported by observations that drugs (LSD, psilocybin)can induce spiritual experiences. Thesedrugs are known to perturb the 5-HT systemin several brain regions. They produce perceptualdistortions, illusions and hallucinations,and sometimes a sense of insight and spiritualawareness, mystical experiences, and religiousecstasy. These effects can resemble the perceptionsand ideation described by subjects whohave experienced spirituality. Some benefits or“side effects” of praying and meditation on psychiatricdisorders could be explained by a modulationof this neurotransmitter (see below).Although 5-HT can be found mainly in thegastrointestinal tract, 5-HT is also a monoaminethat serves as a neurotransmitter in thebrain. Serotonergic neurons that synthesize2.2. DopamineDopamine is produced in several areas ofthe brain. It is the primary neurotransmitterinvolved in the reward pathways and is commonlyassociated with the pleasure systemof the brain. Drugs that increase dopaminesignaling (like cocaine), particularly in thenucleus accumbens, may produce euphoriceffects. Psychostimulants, such as amphetamineand cocaine, induce dramatic changes indopamine signaling; large doses and prolongeduse can induce symptoms that resemble schizophrenia.Moreover, in the mesolimbic pathway,dopamine increases arousal and goal-directedbehaviors.Given its importance in many personalitytraits or dimensions such as anger-relatedtraits (1) and the main role of this neurotransmitterin the function of the frontal lobes, dopaminehas also been investigated in spirituality.Moreover, from a psychiatric point of view,perturbation of dopaminergic systems has beensuggested in psychiatric disorders includingschizophrenia, Parkinson’s disease, and drugand alcohol dependence. Of note, dopaminergicneurons are also under the control of the5-HT system.