A panic disorder. Experts estimate that 2-3% of the American population suffers from a panic or anxiety disorder.

It's difficult to categorize one as being "worse" than the other because they are interconnected. Panic disorder involves experiencing recurring panic attacks, which are the defining feature of the disorder. In this sense, panic disorder encompasses the experience of panic attacks. However, not all panic attacks lead to a diagnosis of panic disorder. Panic attacks can occur as isolated incidents or in the context of other anxiety disorders, without meeting the criteria for panic disorder.

It's kind of straight forward...you panic, its a disorder

A generalized anxiety disorder (GAD) or panic disorder.

Who was the first to discover panic disorder?? Well, your question is not very clear. Do you mean who is the first person to actually diagnose and give the name 'panic disorder' to this condition? or do you mean who was the first person to actually 'develop' panic disorder?? Panic disorder is when a person has been suffering one month or more from panic attacks, and has been worried about the reoccurance of these attacks. I should think that people have been suffering from this disorder for many years - particuarly stressed people or perfectionists. The term panic disorder is just a follow on from panic attacks. No-one 'discovered' panic attacks or panic disorder. You make it sound like the discovery of a new unfound island or country!