Cotard's Syndrome or Walking Corpse Syndrome.
It seems unlikely that many atheists think about such things! But, atheism isn't considered a mental disorder.
There are so many . . . I can think of bipolar disorder, depression, disassociation disorder, panic disorder, personality disorder, asocial disorder among the many.
Yes schizophrenia is a mental disorder and can be very damaging towards your brain. If you think you might have it, consult your doctor about it, and he may go along with it taking you to a psychiatrist.
Anorexia nervosa is indeed a mental disorder.
A hypochondriac
Liberalism Is a Mental Disorder has 221 pages.
A mental disorder is defined by psychological symptoms some of which are called psychopathological phenomena.
An addiction disorder
Do you mean "mental" disorder?
Doctors think that bipolar disorder is caused by stress. Others believe that it's a mental illness that you can treat with medicine.
According to the Diagnostic and Statistical Manual of Mental Disorders, phobias are considered to be sub-types of anxiety disorder (psychiatric disorder).
Yes, dissociative identity disorder (formerly known as multiple personality disorder) is a mental disorder where a person has two or more distinct personality states. Each personality state may have its own unique way of thinking, behaving, and relating to the world.