When people are confronted with unpleasant and potentially harmful stimuli such as foul odors or tastes, PET-scans show increased bloodflow in the amygdala.[87][88] In these studies, the participants also reported moderate anxiety. This might indicate that anxiety is a protective mechanism designed to prevent the organism from engaging in potentially harmful behaviors.

DBT uses a skills-based approach to help patients regulate their emotions. It is a prefered treatment for Borderline Personality Disorder, but call also be effective for anxiety disorders such as PTSD. This treatment teaches patients how to develop skills for how to regulate their emotions, stress-management, mindfulness, and interpersonal effectiveness. It was developed to be employed in either one-on-one therapy sessions or group sessions. This type of therapy is typically long-term and patients are usually in treatment for a year or more.
Post-traumatic stress disorder (PTSD) is an extreme anxiety disorder that can occur in the aftermath of a traumatic or life-threatening event. PTSD can be thought of as a panic attack that rarely, if ever, lets up. Symptoms of PTSD include flashbacks or nightmares about what happened, hypervigilance, startling easily, withdrawing from others, and avoiding situations that remind you of the event.
Genetics and family history (e.g., parental anxiety) may predispose an individual for an increased risk of an anxiety disorder, but generally external stimuli will trigger its onset or exacerbation.[57] Genetic differences account for about 43% of variance in panic disorder and 28% in generalized anxiety disorder.[58] Although single genes are neither necessary nor sufficient for anxiety by themselves, several gene polymorphisms have been found to correlate with anxiety: PLXNA2, SERT, CRH, COMT and BDNF.[59][60][61] Several of these genes influence neurotransmitters (such as serotonin and norepinephrine) and hormones (such as cortisol) which are implicated in anxiety. The epigenetic signature of at least one of these genes BDNF has also been associated with anxiety and specific patterns of neural activity.[62]

In people with anxiety disorders, the brain circuitry that controls the threat response goes awry. At the heart of the circuit is the amygdala, a structure that flags incoming signals as worrisome and communicates with other parts of the brain to put the body on alert for danger. Early life events, especially traumatic ones, can program the circuitry so that it is oversensitive and sends out alarms too frequently and with only minor provocations. Survival mandates a system for perceiving threats and taking quick, automatic action, but those with anxiety see threats where there are none, perhaps because emotional memories color their perceptions.
Panic attacks can happen during the day or night. Some people have one panic attack then don't ever experience another, or you might find that you have them regularly, or several in a short space of time. You might notice that particular places, situations or activities seem to trigger panic attacks. For example, they might happen before a stressful appointment.
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.