Psychiatrists won't diagnose a panic disorder unless a patient already has four of the common signs or symptoms associated with GAD -the symptoms listed under those that are the hallmarks of both long-standing stress and GAD.
The Greeks were not constrained in this way, as shown by the etymology of our modern word 'panic'. Pan was the Greek god of pastures, forest, fertility, flocks and herds. Half-man and half-goat, he had an overdeveloped libido and was accustomed to hide in remote spots in the mountains where he would suddenly pounce out upon the unwary traveller. Not unnaturally, these travellers suffered 'acute episodes of intense anxiety'. They didn't need to have had any previous history of troubles to be diagnosed as being in a state of 'panic' - a state of mind derived from the actions of the god Pan.
Only five percent of the population suffers from GAD, and with it, a tendency to panic disorders, yet a third of people at some time or another during their lives have had a panic attack. Ten percent have had more than one episode. Often it is a panic attack that initially drives a patient with a long-standing anxiety disorder to the doctor's surgery to discuss the situation. A characteristic of a panic attack is that it is usually impossible for the patient to do much about the precipitating cause. Doctors always bear in mind that anxiety disorders and panic disorders are not only closely related to each other, but they are also related to depression. Sixty percent of patients who suffer panic attacks are also depressed from time to time.