According to WebMD, anxiety is caused by the use of drugs, psychological conditions, physical conditions or by more than one of these factors at the same time. Anxiety comes in many different forms; some common anxiety disorders include generalized anxiety disorder, obsessive-compulsive disorder, specific phobias, post-traumatic stress disorder and social anxiety disorder. Each of these conditions may have different root causes but all share anxiety as a common feature.
Mayo Clinic states that psychological causes of anxiety are largely unknown; however, persons predisposed to anxiety disorders may develop them in response to traumatic life events. Some physiological causes of anxiety include diabetes, heart disease, premenstrual syndrome, irritable bowel syndrome, asthma and rare types of tumors. Withdrawal from, or abuse of, drugs is also known to cause anxiety. Persons who are ending an anti-anxiety medication regimen may experience anxiety as a withdrawal symptom.
ABC News reports that Dr. James Greenblatt found success treating an anxious patient using powerful probiotics. The patient's anxious symptoms came as a result of low levels of good bacteria in her digestive tract and were relieved by increasing the amounts of good bacteria. Additionally, ABC News reports that scientists have also discovered a link between strep throat bacterium and obsessive-compulsive disorder.