Generalized Anxiety Disorder
Generalized anxiety disorder (GAD) is an anxiety disorder characterized by excessive, uncontrollable and often irrational worry, that is, apprehensive expectation about events or activities. This excessive worry often interferes with daily functioning, as individuals with GAD typically anticipate disaster, and are overly concerned about everyday matters such as health issues, money, death, family problems, friendship problems, interpersonal relationship problems, or work difficulties. Individuals often exhibit a variety of physical symptoms, including fatigue, fidgeting, headaches, nausea, numbness in hands and feet, muscle tension, muscle aches, difficulty swallowing, excessive stomach acid buildup, stomach pain, vomiting, diarrhea, bouts of breathing difficulty, difficulty concentrating, trembling, twitching, irritability, agitation, sweating, restlessness, insomnia, hot flashes, rashes, and inability to fully control the anxiety (ICD-10). These symptoms must be consistent and ongoing, persisting at least six months, for a formal diagnosis of GAD. In a given year, approximately 6.8 million American adults and two percent of European adults experience GAD. GAD is seen in women twice as much as men. GAD is also common in individuals with a history of substance abuse and a family history of the disorder. Once GAD develops, it may become chronic, but can be managed or eliminated with proper treatment.
Standardized rating scales such as GAD-7 can be used to assess severity of GAD symptoms. GAD is the most common cause of disability in the workplace in the United States.
Causes
Genetics
About a third of the variance for generalized anxiety disorder has been attributed to genes. Individuals with a genetic predisposition for GAD are more likely to develop GAD, especially in response to a life stressor.
Substance induced
Long-term use of benzodiazepines can worsen underlying anxiety, with evidence that reduction of benzodiazepines can lead to a lessening of anxiety symptoms. Similarly, long-term alcohol use is associated with anxiety disorders, with evidence that prolonged abstinence can result in a disappearance of anxiety symptoms. However, it can take up to two years for anxiety symptoms to return to baseline in about a quarter of people recovering from alcoholism. In one study in 1988–90, illness in approximately half of patients attending mental health services at British hospital psychiatric clinic, for conditions including anxiety disorders such as panic disorder or social phobia, was determined to be the result of alcohol or benzodiazepine dependence. In these patients, anxiety symptoms, while worsening initially during the withdrawal phase, disappeared with abstinence from benzodiazepines or alcohol. Sometimes anxiety pre-existed alcohol or benzodiazepine dependence, but the dependence was acting to keep the anxiety disorders going and often progressively making them worse. Recovery from benzodiazepines tends to take a lot longer than recovery from alcohol, but people can regain their previous good health.
Tobacco smoking has been established as a risk factor for developing anxiety disorders.
Excessive Caffeine usage has been linked to anxiety.
Mechanisms
Generalized anxiety disorder has been linked to disrupted functional connectivity of the amygdala and its processing of fear and anxiety. Sensory information enters the amygdala through the nuclei of the basolateral complex (consisting of lateral, basal and accessory basal nuclei). The basolateral complex processes the sensory-related fear memories and communicates their threat importance to memory and sensory processing elsewhere in the brain, such as the medial prefrontal cortex and sensory cortices.
Another area, the adjacent central nucleus of the amygdala, controls species-specific fear responses in its connections to the brainstem, hypothalamus and cerebellum areas. In those with generalized anxiety disorder, these connections seem less functionally distinct, and there is greater gray matter in the central nucleus. Another difference is that the amygdala areas have decreased connectivity with the insula and cingulate areas that control general stimulus salience, while having greater connectivity with the parietal cortex and prefrontal cortexcircuits that underlie executive functions. The latter suggests a compensation strategy for dysfunctional amygdala processing of anxiety. This is consistent with cognitive theories that suggest the use in this disorder of attempts to reduce the involvement of emotions with compensatory cognitive strategies
Prevention
Focus is increasing on prevention of mental disorders. Avoidance of caffeine may prevent GAD. Additionally, avoiding nicotine decreases the risk for the development of anxiety disorders including generalized anxiety disorder.
Comorbidity
GAD and depression
In the National Comorbidity Survey (2005), 58 percent of patients diagnosed with major depression were found to have an anxiety disorder; among these patients, the rate of comorbidity with GAD was 17.2 percent, and with panic disorder, 9.9 percent. Patients with a diagnosed anxiety disorder also had high rates of comorbid depression, including 22.4 percent of patients with social phobia, 9.4 percent with agoraphobia, and 2.3 percent with panic disorder. A longitudinal cohort study found 12% of the 972 participants had GAD comorbid with MDD. Accumulating evidence indicates that patients with comorbid depression and anxiety tend to have greater illness severity and a lower treatment response than those with either disorder alone. In addition, social function and quality of life are more greatly impaired.
For many, the symptoms of both depression and anxiety are not severe enough (i.e. are subsyndromal) to justify a primary diagnosis of either major depressive disorder (MDD) or an anxiety disorder. However, dysthymia is the most prevalent comorbid diagnosis of GAD clients. Patients can also be categorized as having mixed anxiety-depressive disorder, and they are at significantly increased risk of developing full-blown depression or anxiety.
GAD and substance abuse disorders
Those with GAD have a lifetime comorbidity prevalence of 30% to 35% with alcohol abuse and dependence and 25% to 30% for drug abuse and dependence. Sufferers of both GAD and a substance abuse disorder also have a higher lifetime prevalence for other comorbidities. A study found that GAD was the primary disorder in slightly more than half of the 18 participants that were comorbid with alcohol use disorder.
Other comorbidities
In addition to coexisting with depression, research shows that GAD often coexists with conditions associated with stress, such as irritable bowel syndrome. Patients with GAD can sometimes present with symptoms such as insomnia or headaches as well as pain, cardiac events and interpersonal problems.
Further research suggests that about 20 to 40 percent of individuals with attention deficit hyperactivity disorder have comorbid anxiety disorders, with GAD being the most prevalent.
The World Health Organization's Global Burden of Disease project did not include generalized anxiety disorders. In lieu of global statistics, here are some prevalence rates from around the world:
• Australia: 3 percent of adults
• Canada: Between 3 and 5 percent of adults
• Italy: 2.9 percent
• Taiwan: 0.4 percent
• United States: approx. 3.1 percent of people age 18 and over in a given year (9.5 million)
The usual age of onset is variable, from childhood to late adulthood, with the median age of onset being approximately 31 and mean age of onset is 32.7. Most studies find that GAD is associated with an earlier and more gradual onset than the other anxiety disorders. The prevalence of GAD in children is approximately 3%; the prevalence in adolescents is reported as high as 10.8%. When GAD appears in children and adolescents, it typically begins around 8 to 9 years of age.
Populations that are at an increased risk of GAD are individuals with low and middle socio-economic status, separated, divorced, and widowed individuals. Women are twice as likely to develop GAD as men. This is primarily because women are more likely than men to live in poverty, be subject to discrimination, and be sexually and physically abused. GAD is also common in the elderly population.
Compared to the general population, patients with internalizing disorders such as depression, generalized anxiety disorder (GAD) and post-traumatic stress disorder (PTSD) have higher mortality rates, but die of the same age-related diseases as the population, such as heart disease, cerebrovascular disease and cancer.