Obsessive Compulsive Disorder and Family Influence . One recent study found that parental influence played no part in obsessive-compulsive disorder when the patient was also not suffering from depression. Some individuals may even have a biological propensity for specific fears, for instance of spiders or snakes, that can be triggered and perpetuated after a single first exposure. A number of studies have reported a strong link between childhood rheumatic fever, which is caused by a streptococcal infection, and the development of tic-related disorders, including OCD and Tourette's syndrome. The effects of alcohol on the developing fetus now appear to increase the risk for mental disorders as well as birth defects.
Anxiety disorders run in families and genetic or biological factors play a role in most forms.
Studies have suggested that extremely shy children and those likely to be the target of bullies are at higher risk for developing anxiety disorders later in life. One study suggests that such children could be identified as early as two years of age and possibly treated to avoid later anxiety disorders. Prolonged television viewing also puts children at risk for anxiety, depression, and behavioral problems. Panic disorders tend to begin in late adolescence and peak at around 25 years of age. The risk for generalized anxiety disorder spans a lifetime although it appears to be the most common form of anxiety at older ages.