The majority of mental illnesses are reactions to adverse situations experienced in life, from the horrific to the merely strange. Most first become manifest in early adulthood. Some underlying predispositions exist. The question of 'nature vs nurture' would appear to be irrelevant. Inherited factors, mainly dealing with neurochemistry and perception are as important as personality styles developed during childhood and adolescence.
Anxiety is a normal physiological response in anticipation of a potential stressor.
It is very useful - up to a point. Beyond this limit, it becomes counter-productive, even destructive. Headaches, abdominal pain, palpitations, nausea, vomitting, diarrhoea, 'pins and needles' in the extremities, and a general feeling of impending doom are symptoms of a severe anxiety attack. We can regard anxiety disorders as arising from Inappropriate stressors Inappropriate threshold for initiating anxiety response, or Inappropriate response to stressors. Phobias We usually remember bad events rather than good ones.