It may be in the elusive nature of emotions in general that the exact causes of anxiety disorders are still not fully understood. Anxiety disorders have been linked to social-environmental and emotional factors, overactive neurological pathways and changes in brain chemistry. However, it is most likely that, in the majority of cases, a mixture of factors contribute to the onset of the condition.
It is well established that past traumas — such as verbal, emotional, physical or sexual abuse — as well as chronic stress increase the likelihood of developing an anxiety disorder.
A number of studies found that frequent stress and anxiety alters the activity of certain regions of the midbrain, which results in a heightened responsiveness to anxiety triggers. In particular, the amygdala (a small, almond-shape aggregation of nuclei) appears to play a major role in the development of anxiety disorders.
From a psychological perspective, it appears that high levels of stress and anxiety over a long period of time cause changes on a subconscious level, which lead to a distorted perspective on reality. The more prominent these distortions, the faster and stronger a person reacts to anxiety triggers until even rather harmless situations are overinterpreted as potential peril. These subconscious changes can also explain why logic and rational thinking are usually ineffective to overcome an anxiety attack.
Biochemical Changes in the Brain
Researchers found a connection between the concentrations of certain neurotransmitters in the brain and the onset of anxiety disorders. Neurotransmitters are released by neurons and some glands, such as the pituitary gland and the adrenals, and function as messengers between the nervous system and the rest of the body. Once released, neurotransmitters bind to specific membrane receptors, like keys fitting into their corresponding locks, and thus initiate distinctive responses and chemical changes within the cells.
Epinephrine, norepinephrine, serotonin and gamma-aminobutyric acid (GABA) are neurotransmitters in the brain that are involved in the anxiety pathway. Whereas epinephrine and norepinephrine are involved in the stress and anxiety response, GABA and serotonin are known to stimulate positive feelings and improve your mood. Low concentrations of GABA and serotonin, which can be caused by a lack of protein intake, chronic stress and genetic predispositions, increase the likelihood of developing an anxiety disorder. Many antianxiety medications function on the basis of raising serotonin and GABA levels in the brain.
Anxiety appears to run in families. However, the question is whether family members are more prone to have anxiety due to environmental factors they share or because they have the same genes. While genetic research has become highly advanced in the past 20 years, there is still only limited information on the genetic predisposition of anxiety disorders. Studies with identical twins demonstrated that, although anxiety can be hereditary, genes only explain roughly 30 to 40 percent of why a person develops an anxiety disorder or not.
Recent research has been focusing more on how epigenetic factors may contribute to the onset of anxiety disorders. Epigenetics explores how our environment can cause the activation or deactivation of certain genes. DNA methylation is one of the most common ways cells turn a gene off in response to changes in the environment. Scientists found that stress and anxiety during pregnancy can be passed on to the child through epigenetic changes. It turns out that in fetuses and infants of mothers who have been struggling with depression and stress, the gene of the glucocorticoid receptor (GCR) can be highly methylated. The methylation of the GCR causes an excessive release of stress hormones, which makes infants react more strongly to stress and anxiety triggers.
Anxiety disorders can also be caused by certain health issues, such as anemia, thyroid problems, heart disease, chronic pain and diabetes. Other factors include drug and alcohol abuse, withdrawal from certain medications, sleep deprivation and excessive consumption of caffeine.
Given the multifactorial reasons for developing an anxiety disorder, it makes sense to approach its treatment from a variety of angles, including psychotherapy, lifestyle changes and, if appropriate, antianxiety medication.
- Generalized anxiety disorder: nature and course
- Serotonin norepinephrine reuptake inhibitors (SNRIs) in anxiety disorders: a comprehensive review of their clinical efficacy.
- The Role of Childhood Trauma in the Neurobiology of Mood and Anxiety Disorders: Preclinical and Clinical Studies
- COMT haplotypes modulate associations of antenatal maternal anxiety and neonatal cortical morphology.