Research has shown that women are twice as likely to be affected by panic attacks. ​The mean age at onset for panic attack in US is approximately 22-23 years old.  This is more related to a weaker autonomic response to emotional states in older individual compared to younger individuals. ​Negative affectivity (i.e., proneness to experiencing negative emotions) and anxiety sensitivity (i.e., the disposition to believe that symptoms of anxiety are harmful) are risk factors for the onset of panic attacks, as well as worry about panic.  Childhood experiences of sexual or physical abuse are more common in panic disorder.  Smoking is a risk factor also for panic attacks and panic disorders.  Personal stressors (e.g., interpersonal conflicts, diseases, or death in family, use of illicit drugs) are often identified as stressors before the first panic attack.