Today, we have a better understanding of mental disorders and there are various theories to define mental disorders. Anxiety disorders are a common type of mental disorder characterized by anxiety caused without any rational causes.
Phobia is a type of anxiety disorder distinguished by irrational fear.
Generalized anxiety disorders have no cause for anxiety. It is thought that these disorders may be genetic. Somatoform disorders are characterized by physical illnesses that cannot be explained by medical evidence. Conversion disorder is when psychological stress causes the loss of physical functions. Hypochrondias is the belief of having a serious medical conditions.