Anxiety can range from an occasional mild feeling of emotional discomfort to daily occurrences of disabling emotions. The National Institute of Mental Health says that approximately 40 million Americans aged 18 or older have an anxiety disorder. There are many situational causes of anxiety. Understanding the underlying physiological connections to this common emotional malady can be important to preventing or reducing incidences of anxiety.
Definition of Anxiety
People experiencing anxiety tend to interpret situations as threatening, even when in reality, no threat exists. Anxiety can present itself in individuals in a number of ways, including panic attacks, phobias -- fears that are out of proportion with actual circumstances -- obsessive-compulsive behavior and post-traumatic stress disorder.
How Anxiety Occurs
Scientists believe mental illnesses result from the combined impact of genetic, environmental, psychological and developmental factors. Exactly how those factors combine to add up to anxiety is still largely unknown. The basic mechanism seems to be that some individuals have a disproportionate response to certain stimuli -- for example an image, a sound, a scent -- whereas other individuals' brains do not have such strong reactions. Brain research has revealed that the amygdala and hippocampus are key players in most anxiety disorders. The amygdala is where emotional memories are stored, while the hippocampus is important to learning and memory. The amygdala is where the primal fight-or-flight reflex begins. Recent research in the journal "Neuron" found that individuals have varying skill levels regarding both how they perceive danger or stress and then whether a person activates part of the brain called the ventral prefrontal cortex.
Definition of Dopamine
Dopamine is one of several chemicals, called neurotransmitters, that help signals travel between brain cells. These signals are how your brain tells your body what to do. Dopamine, particularly, is connected to the emotions you feel. High levels of dopamine are responsible for the sensation of reward you feel after certain activities, like sex. Low levels of dopamine can result in depression and weight gain, and chronically low levels can be an indicator of the neuro-mobility condition called Parkinson's disease.
Changing Dopamine Levels
The amount of dopamine your body produces can be altered as a result of stress, antidepressant medications, the use of some recreational drugs, inadequate nutrition and lack of sleep. Dopamine levels elevate in the presence of caffeine, alcohol and sugar. Prescription medications can be used to regulate dopamine levels depending on the resulting illness. For example, the class of drugs called dopamine agonists are used to treat Parkinson's, to raise the neurotransmitter's levels. On the other hand are dopamine antagonists, which may be prescribed to treat mental disorders like schizophrenia by "turning down" the levels.
Connecting Dopamine with Anxiety
A 2008 study in the "Journal of Nuclear Medicine" arrived at a first-time conclusion linking social anxiety disorder -- a specific form of anxiety -- with altered dopamine uptake activity in the striatum, a part of the brain. In "Nature Neuroscience," researchers published results that linked anxiety, emotional processing in the amygdala, and dopamine storage capacity. Specifically, PET scans and MRI studies found that people with more dopamine stored in their left amygdala were less likely to score high on tests for anxiety.
- National Institute of Mental Health: The Numbers Count: Mental Disorders in America
- "Neuron"; Fear-Conditioning Mechanisms Associated With Trait Vulnerability to Anxiety in Humans; Iole Indovina et al.; 2011
- University of Texas, College of Pharmacy, Addiction Science Research and Education Center: Dopamine - A Sample Neurotransmitter
- "Journal of Nuclear Medicine"; Increased serotonin and dopamine transporter binding in psychotropic medication-naive patients with generalized social anxiety disorder shown by 123I-beta-(4-iodophenyl)-tropane SPECT; NJ van der Wee et al.; May 2008.
- "Nature Neuroscience"; Dopamine in amygdala gates limbic processing of aversive stimuli in humans.; T Kienast et al.; December 2008
- The DANA Foundation: Dopamine Linked to 'Anxious' Amygdalas