Those who experience panic attacks are often nervous about having additional episodes. To avoid having a panic attack in a public space, they may avoid places like shopping malls or other crowded spots where previous incidents may have occurred or places that they fear will not allow them immediate access to help, such as an airplane or movie theater. This avoidance when severe may lead to agoraphobia, the inability to leave familiar, safe surroundings because of intense fear and anxiety about having a panic attack outside the home.
Many studies in the past used a candidate gene approach to test whether single genes were associated with anxiety. These investigations were based on hypotheses about how certain known genes influence neurotransmitters (such as serotonin and norepinephrine) and hormones (such as cortisol) that are implicated in anxiety. None of these findings are well replicated., with the possible exception of TMEM132D, COMT and MAO-A. The epigenetic signature of BDNF, a gene that codes for a protein called brain derived neurotrophic factor that is found in the brain, has also been associated with anxiety and specific patterns of neural activity. and a receptor gene for BDNF called NTRK2 was associated with anxiety in a large genome-wide investigation. The reason that most candidate gene findings have not replicated is that anxiety is a complex trait that is influenced by many genomic variants, each of which has a small effect on its own. Increasingly, studies of anxiety are using a hypothesis-free approach to look for parts of the genome that are implicated in anxiety using big enough samples to find associations with variants that have small effects. The largest explorations of the common genetic architecture of anxiety have been facilitated by the UK Biobank, the ANGST consortium and the CRC Fear, Anxiety and Anxiety Disorders.
Anxiety can be either a short-term "state" or a long-term "trait". Whereas trait anxiety represents worrying about future events, anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fear. Anxiety disorders are partly genetic, with twin studies suggesting 30-40% genetic influence on individual differences in anxiety. Environmental factors are also important. Twin studies show that individual-specific environments have a large influence on anxiety, whereas shared environmental influences (environments that affect twins in the same way) operate during childhood but decline through adolescence. Specific measured ‘environments’ that have been associated with anxiety include child abuse, family history of mental health disorders, and poverty. Anxiety is also associated with drug use, including alcohol, caffeine, and benzodiazepines (which are often prescribed to treat anxiety).
Since anxiety disorders are a group of related conditions rather than a single disorder, they can look very different from person to person. One individual may suffer from intense anxiety attacks that strike without warning, while another gets panicky at the thought of mingling at a party. Someone else may struggle with a disabling fear of driving, or uncontrollable, intrusive thoughts. Yet another may live in a constant state of tension, worrying about anything and everything. But despite their different forms, all anxiety disorders illicit an intense fear or anxiety out of proportion to the situation at hand.
^ Eley, Thalia C.; McAdams, Tom A.; Rijsdijk, Fruhling V.; Lichtenstein, Paul; Narusyte, Jurgita; Reiss, David; Spotts, Erica L.; Ganiban, Jody M.; Neiderhiser, Jenae M. (July 2015). "The Intergenerational Transmission of Anxiety: A Children-of-Twins Study". American Journal of Psychiatry. 172 (7): 630–637. doi:10.1176/appi.ajp.2015.14070818. ISSN 0002-953X.
Obsessive-compulsive disorder (OCD) is characterized by unwanted thoughts or behaviors that seem impossible to stop or control. If you have OCD, you may be troubled by obsessions, such as a recurring worry that you forgot to turn off the oven or that you might hurt someone. You may also suffer from uncontrollable compulsions, such as washing your hands over and over.
When we experience an involuntary high degree stress response, the sensations can be so profound that we think we are having a medical emergency, which anxious personalities can react to with more fear. And when we become more afraid, the body is going to produce another stress response, which causes more changes, which we can react to with more fear, and so on.