Great questions. Unfortunately, there is usually no clear cut answer – and like many mental health disorders – it is likely caused by a combination of genetic, behavioral, and developmental factors. Anatomically speaking, Generalized Anxiety Disorder is most closely related to a disruption in the functional connectivity of the amygdala – the “emotional control center” of the brain – and how it processes feelings of fear and anxiety. Genetics also play a role in Generalized Anxiety Disorder. If you have a family member that also suffers from this disorder, your chances of suffering from it are increased, especially in the presence of a life stressor. Interestingly, long-term substance abuse also increases your chances of Generalized Anxiety Disorder, as the use of benzodiazepines can worsen your anxiety levels, as can excessive alcohol use. Tobacco use and caffeine are also both associated with increased levels of anxiety.
Not everyone understands is that someone with an anxiety disorder cannot "just let things go". This makes the struggle with an anxiety disorder even harder, and may prevent one from looking for help. However, it is very important to talk about these anxieties with someone and preferably find a health care professional as soon as you experience these symptoms. Anxiety should be considered as severe as a physical disease; however, most people in society do not appreciate the severity of this disorder. Some people may consider anxiety a fault or a weakness; however, it may help if people realize that many research studies have demonstrated biological explanations for (some of) the symptoms observed in anxiety disorders. Brain scans have demonstrated brain abnormalities in certain anxiety disorders, and also altered brain functioning has been demonstrated for individuals with anxiety disorders. Furthermore, there is some evidence that anxiety disorders might be linked to chemical imbalances in the brain.

Before SSRIs and SSNRIs became available, medications from the group known as the tricyclic antidepressants (TCAs) were often used to address panic disorder. Although TCAs have been found to be equally effective in treating panic attacks, SSRIs and SSNRIs have been proven to be safer and better tolerated. Therefore TCAs are used much less often than they were previously.
In the central nervous system (CNS), the major mediators of the symptoms of anxiety disorders appear to be norepinephrine, serotonin, dopamine, and gamma-aminobutyric acid (GABA). Other neurotransmitters and peptides, such as corticotropin-releasing factor, may be involved. Peripherally, the autonomic nervous system, especially the sympathetic nervous system, mediates many of the symptoms. Increased flow in the right parahippocampal region and reduced serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients are the diagnostic factors for prevalence of anxiety disorder.
Panic attacks are sudden periods of intense fear that may include palpitations, sweating, shaking, shortness of breath, numbness, or a feeling that something bad is going to happen.[1][2] The maximum degree of symptoms occurs within minutes.[2] Typically they last for about 30 minutes but the duration can vary from seconds to hours.[3] There may be a fear of losing control or chest pain.[2] Panic attacks themselves are not typically dangerous physically.[6][7]
For example, once you notice you are scaring yourself with anxious thinking, you can change your thinking to calming thoughts, which will stop stress responses and their physiological, psychological, and emotional effects. As you calm yourself down, your body will follow by stopping the flow of stress hormones. As stress hormones are used up or expelled, the sensations, symptoms, and feelings of panic will subside…in time.
People with generalized anxiety disorder (GAD) display excessive anxiety or worry, most days for at least 6 months, about a number of things such as personal health, work, social interactions, and everyday routine life circumstances. The fear and anxiety can cause significant problems in areas of their life, such as social interactions, school, and work.