Neuroscience of Anxiety Disorders

Introduction

Anxiety is an emotion best characterized as an unpleasant feeling of uneasiness and worry, often manifesting as nervousness involving pacing back and forth, somatic (bodily) complaints such as muscular tension and restlessness, and rumination that may cause fatigue and problems with concentration. While anxiety can be appropriate, for example in stressful circumstances, patients with anxiety disorders suffer from this long-term, overwhelming stress even in normal daily life. According to the National Institute of Mental Health, approximately 1 in 5 people suffer from an anxiety disorder.

Types and Symptoms

There are several different anxiety disorders, and patients can often simultaneously have more than one. These types include:

  • generalized anxiety disorder,
  • specific phobias,
  • panic disorder,
  • agoraphobia,
  • social anxiety disorder,
  • post-traumatic stress disorder,
  • separation anxiety disorder,
  • situational anxiety,
  • obsessive-compulsive disorder,
  • and selective mutism.

The specific type that a patient suffers is diagnosed based on what specifically triggers the symptoms, which include:

  • nervousness, restlessness, or tense feelings,
  • a sense of impending danger, panic or doom,
  • increased heart rate,
  • rapid breathing (hyperventilation),
  • sweating,
  • trembling,
  • weakness or tiredness,
  • concentration issues (or difficulty thinking about anything other than the present worry),
  • trouble sleeping,
  • gastrointestinal (GI) problems,
  • difficulty controlling worry,
  • and urge to avoid things that trigger anxiety.

Causes and Risk Factors

The causes of anxiety disorders haven’t been fully determined. Overall, environmental factors such as traumatic events in those susceptible to anxious feelings seem to be a primary cause. Genetic factors can also be a contributing factor.

In addition, other medical issues may cause anxiety disorder, such as in:

  • heart disease,
  • diabetes,
  • thyroid issues (such as hyper- or hypo-thyroidism),
  • respiratory problems (such as COPD and asthma),
  • drug abuse/withdrawal,
  • withdrawal from alcohol, anti-anxiety medications, or even other medications,
  • chronic pain,
  • irritable bowel syndrome,
  • rare tumors that produce certain fight-or-flight hormones.
  • and even side effects of certain medications.

Factors that may put a person at risk of developing an anxiety disorder include:

  • traumatic events,
  • stress due to illness,
  • stress building up,
  • susceptible personalities,
  • other mental health issues,
  • blood relatives with an anxiety disorder,
  • and drug or alcohol use.

Underlying Mechanisms

The primary neurotransmitter (chemical substances involved in brain signaling) believed to be involved in causing anxiety disorders is gamma-aminobutyric acid, better known as GABA. GABA reduces activity in the central nervous system, which includes the brain and spinal cord, and low levels contribute to anxiety.

Serotonin is also believed to may play a role in anxiety disorders as well, evident by the frequent use of SSRI’s (selective serotonin reuptake inhibitors) as first-line treatment for this condition.

The main part of the brain affected in those with anxiety disorders is the amygdala, where processing of fear and anxiety occurs:

  • Typically, sensory information from a person’s environment is connected to the basolateral complex nuclei of the amygdala, where memories related to fear are, and then communicated to further memory processing and also sensory processing elsewhere in the brain, for example the medial prefrontal cortex and sensory cortices, respectively. Parts of this circuit may be maladapted in those with anxiety disorders.
  • The central nucleus of the amygdala controls fear responses via connections to the brainstem, hypothalamus, and cerebellum. Patients with generalized anxiety disorder have functionally less distinct connections, and there is more grey matter in the central nucleus itself.
  • There is less connectivity from the amygdala to areas that control general stimulus prominence such as the insula and cingulate, while there is more connectivity to areas that control executive functions such as the parietal and prefrontal cortices. This suggests a compensatory cognitive mechanism to prevent unwelcome anxious emotions in those affected by the disorder.

Prevention and Treatment Options

Steps that one can take to reduce the risk of developing an anxiety disorder include:

  • getting treatment early
  • staying active and socializing
  • and avoiding alcohol or drug abuse.

If one does develop an anxiety disorder, the primary treatment options are psychotherapy, medications, or a combination of both depending on what works best for the patient.

Psychotherapy involves working with a therapist to best reduce your anxiety symptoms and gradually return to anxiety-provoking activities.

Cognitive behavioral therapy, also known as CBT, is the most effective form of psychotherapy in treating anxiety disorders.

A combination of CBT and mindfulness and stress reduction techniques has been proven to be effective.

Medications include:

  • some antidepressants (such as SSRI’s and SNRI’s) that are also effective in treating anxiety,
  • Specific anti-anxiety medications
  • and short-term relief medications such as sedatives in the benzodiazepine drug class, or even beta-blockers that reduce blood pressure.

Conclusion

An anxiety disorder can be a crippling condition, but with the proper medical and psychological support, patients can return to a healthy life. If you or a loved one is suffering from an anxiety disorder, our office provides necessary support services that can help you do just that.

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