Everyone periodically experiences fear and anxiety.
Fear is an emotional, physical, and behavioral response to an immediately recognizable external threat (eg, an intruder, a car spinning on ice).
Anxiety is a distressing, unpleasant emotional state of nervousness and uneasiness; its causes are less clear. Anxiety is less tied to the exact timing of a threat; it can be anticipatory before a threat, persist after a threat has passed, or occur without an identifiable threat. Anxiety is often accompanied by physical changes and behaviors similar to those caused by fear.
Some degree of anxiety is adaptive; it can help people prepare, practice, and rehearse so that their functioning is improved and can help them be appropriately cautious in potentially dangerous situations. However, beyond a certain level, anxiety causes dysfunction and undue distress. At this point, it is maladaptive and considered a disorder.
Anxiety occurs in a wide range of physical and mental disorders, but it is the predominant symptom of several. Anxiety disorders are more common than any other class of psychiatric disorder. However, they often are not recognized and consequently not treated. Left untreated, chronic maladaptive anxiety can contribute to or interfere with treatment of some general medical disorders.
Mental distress that occurs immediately or shortly after experiencing or witnessing an overwhelming traumatic event is no longer classified as an anxiety disorder. Such disorders are now classified as trauma-related Posttraumatic Stress Disorder (PTSD) Posttraumatic stress disorder (PTSD) is recurring, intrusive recollections of an overwhelming traumatic event; recollections last > 1 month and begin within 6 months of the event. The pathophysiology... read more and stressor-related disorders Acute Stress Disorder Acute stress disorder is a brief period of intrusive recollections occurring within 4 weeks of witnessing or experiencing an overwhelming traumatic event. (See also Overview of Trauma- and Stressor-Related... read more .
Etiology of Anxiety Disorders
The causes of anxiety disorders are not fully known, but both psychiatric and general medical factors are involved. Many people develop anxiety disorders without any identifiable antecedent triggers. Anxiety can be a response to environmental stressors, such as the ending of a significant relationship or exposure to a life-threatening disaster.
Some general medical disorders can directly cause anxiety; they include the following:
A variety of drugs can cause anxiety. Corticosteroids, cocaine, amphetamines, and caffeine can directly cause anxiety symptoms, while withdrawal from alcohol Alcohol Toxicity and Withdrawal Alcohol (ethanol) is a central nervous system depressant. Large amounts consumed rapidly can cause respiratory depression, coma, and death. Large amounts chronically consumed damage the liver... read more , sedatives, and some illicit drugs can also cause anxiety.
Symptoms and Signs of Anxiety Disorders
Anxiety can arise suddenly, as in panic, or gradually over many minutes, hours, or days. Anxiety may last from a few seconds to years, though a longer duration is more characteristic of anxiety disorders. Anxiety ranges from barely noticeable qualms to intense panic. The ability to tolerate a given level of anxiety varies from person to person.
Anxiety disorders can be so distressing and disruptive that depression may result. Alternatively, an anxiety disorder and a depressive disorder Depressive Disorders Depressive disorders are characterized by sadness severe enough or persistent enough to interfere with function and often by decreased interest or pleasure in activities. Exact cause is unknown... read more may coexist, or depression may develop first, with symptoms and signs of an anxiety disorder occurring later.
Diagnosis of Anxiety Disorders
Exclusion of other causes
Assessment of severity
Deciding when anxiety is so dominant or severe that it constitutes a disorder depends on several variables, and physicians differ at what point they make the diagnosis. Physicians must first use history, physical examination, and appropriate laboratory tests to determine whether anxiety is due to a general medical disorder or drug. They must also determine whether anxiety is better accounted for by another mental disorder.
An anxiety disorder is present and merits treatment if the following apply:
Other causes are not identified.
Anxiety is very distressing.
Anxiety interferes with functioning.
Anxiety does not stop spontaneously within a few days.
Diagnosis of a specific anxiety disorder is based on its characteristic symptoms and signs. Clinicians usually use specific criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which describes the specific symptoms and requires exclusion of other causes of symptoms.
A family history of anxiety disorders helps in making the diagnosis because some patients appear to inherit a predisposition to the same anxiety disorders that their relatives have, as well as a general susceptibility to other anxiety disorders. However, some patients appear to acquire the same disorders as their relatives through learned behavior.
Treatment of Anxiety Disorders
Disorder-specific psychotherapy
Drugs (benzodiazepines, SSRIs)
Treatments vary for the different anxiety disorders, but typically involve a combination of psychotherapy specific for the disorder and drug treatment. The most common drug classes used are the benzodiazepines Benzodiazepines 
and selective serotonin reuptake inhibitors Selective Serotonin Reuptake Inhibitors (SSRIs) Several drug classes and drugs can be used to treat depression: Selective serotonin reuptake inhibitors (SSRIs) Serotonin modulators (5-HT2 blockers) Serotonin-norepinephrine reuptake inhibitors... read more (1, 2 Treatment references Everyone periodically experiences fear and anxiety. Fear is an emotional, physical, and behavioral response to an immediately recognizable external threat (eg, an intruder, a car spinning on... read more ).
Treatment references
Bandelow B, Michaelis S, Wedekind D: Treatment of anxiety disorders. Dialogues Clin Neurosci19(2):93–107, 2017.
Craske MG, Stein MB: Anxiety. Lancet 388:3048–3059, 2016. doiI: 10.1016/S0140-6736(16)30381-6.
