Aetiology
There is no single aetiology for GAD, but an increase in minor life stressors, the presence of physical or emotional trauma, and genetic factors all seem to contribute.[18][19][20]
Childhood risk factors that predispose to later GAD include maltreatment, parental mental health problems or substance use, family disruption (e.g., divorce), and exposure to an overly harsh or over-protective parenting style.[21][22][23] Some evidence suggests that a style of parenting known as 'challenging parenting' (which involves encouraging children to push their limits) seems to be associated with a reduced risk of childhood anxiety when used by fathers, but not by mothers.[24]
One systematic review found that bullying or peer victimisation among adolescents was associated with an increased incidence of anxiety.[25] A review of case control studies found increased rates in people experiencing civilian trauma in 4 of 5 studies, compared with the non-traumatised control population.[20]
Systematic reviews found a significant familial aggregation of GAD (odds ratio 6.1).[26] Another review of 35 twin and family studies found a significant association with other anxiety disorders and depression, suggesting a common underlying genetic factor.[27] Several genetic factors associated with GAD have been identified.[28]
Pathophysiology
The pathophysiology of GAD is not clearly understood, but biological studies have focused on abnormal responses to fear, multiple neurotransmitter involvement, cerebral blood flow, neurohormone alterations, sleep disturbances, and genetic factors.[29][30][31][32]
Multiple neurotransmitters involving many areas of the brain have been implicated in anxiety and other disorders, including receptors for benzodiazepines, serotonin, and noradrenaline.[33]
Abnormalities in brain corticotrophin-releasing factor secretion in the hypothalamic-pituitary-adrenal axis appear to co-occur in patients with GAD and may adversely affect neurotransmitters and arousal.[33] The associated heightened vigilance and arousal are associated with insomnia and diurnal fatigue.[34]
Brain imaging studies, primarily functional magnetic resonance imaging, demonstrate over-activity in parts of the limbic system, such as the amygdala and the insula, following emotional stimuli. There is also evidence of differences in connectivity between the limbic regions and the medial prefrontal cortex.[35][36][37] Overall, the neuroimaging findings suggest deficient cortical 'top-down' control of emotional responses.
Classification
Clinical classification[1]
Excessive anxiety and worry (apprehensive expectation) about a number of events or activities (such as work or school performance) that occur more days than not for at least 6 months. The anxiety, worry, or physical symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. The individual finds it difficult to control the worry. The disturbance is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication) or another medical condition (e.g., hyperthyroidism), and is not better explained by another mental disorder.
Use of this content is subject to our disclaimer