According to the Merck Manual, delusional disorder generally presents itself in middle to late adulthood. It may begin with individuals becoming seemingly obsessed with things, like the loyalty of friends and family members, or a general distrust of people. Suspicion, belief that they are being exploited, perceiving threats where they may not actually exist, reading more into a situation than is necessary, and quick reaction to anything that might be construed as a slight are common warning signs for delusional disorder.
Many times, the delusions a person suffers from seem perfectly logical, as they may be things that could actually happen in real life. Examples include the idea that a lover is cheating, that the boss is conspiring to fire the individual, that a friend may secretly work for the government, etc. These are called non-bizarre delusions. Prior to the publication of the newest Diagnostic and Statistical Manual of Mental Disorders, the DSM-5, in order for a diagnosis of delusional disorder to be made, the delusions had to be non-bizarre in nature. The DSM-5, in contrast to the DSM-IV and previous versions, includes bizarre delusions as well as non-bizarre ones. Bizarre delusions may be more “out there” and less plausible, such as the belief that someone switched out one’s internal organs or that one has insects crawling under their skin.
These delusions do not significantly interfere with a person’s life, however, and the individual may not seem to have an issue unless the delusional beliefs are stirred up. Mood disturbances may accompany delusions; however, they are typically short-lived. Anger, paranoia, violence, and irritability may be side effects of suffering from delusions and may therefore occur as the result of delusional disorder. Social isolation, relationship issues, legal battles, an unwillingness to accept necessary medical care, and troubles at work or school may be consequences of untreated delusional disorder, as these difficulties may be the result of persisting delusions as well.
People suffering from delusional disorder may, on some level, understand that their delusions are untrue, but be unable to shake them. Delusions can progress over time, and proper treatment can help individuals to learn how to manage these delusions as they arise and keep them from interfering with everyday living.