The U.S. Surgeon General's Report on Mental Illness in 2007 stated "Mental disorders are health conditions that are characterized by alterations in thinking, mood or behavior (or some combination thereof) associated with distress and/or impaired functioning." While most disorders fall into general categories, there are a handful of problems which are rarely seen by health professionals.
Capgras Delusion
Medical researcher H. D. Ellis, working in the School of Psychology at the University of Wales Cardiff explains that "People experiencing the Capgras delusion claim that others, usually those quite close emotionally, have been replaced by near-identical impostors." The imposters may be perceived as robots or space aliens. The rarest type of this disorder is found in healthy individuals that lose cognative facial recognition functions after experiencing a serious illness or surgery, according to the British research team of C. Jones, R.D. Griffiths and G. Humpris. The condition was linked by researchers in 1996 to brain lesions.
Fregoli Delusion
This condition is named for an Italian actor deemed to be a master of disguises. People with this disorder believe that an individual impersonates other people in an effort to persecute them. The first case was reported in the medical literature in the late 1920s. Medical researchers suspect brain dysfunction as a primary cause.
Cotard's Delusion
Delusion of missing internal organs or body parts, even removal of a soul, describe the statements made by people with Cotard's delusion. Even though Charles Bonnet made the first medical notation of the delusion in 1788, the condition takes the name of Dr. Jules Cotard, a French neurologist, who described it in 1880. Dr. J. Pearn, writing in the "Journal of Neurology," reports "Cotard's delusion is the only self-certifiable syndrome of delusional psychosis." The causes of this disorder are widely debated.
Diogenes Syndrome
While Diogenes syndrome (also known as senile squalor syndrome, senior self-neglect or senile breakdown) is better known than other conditions listed in this article, it is still viewed as a rare condition. People with this mental disorder typically disregard personal hygiene, collect trash and hoard items. Since the condition is seen more often in the elderly, researchers speculate that it may have causes related to aging and brain dysfunction.
Stockholm Syndrome
Much has been written about Stockholm syndrome, also known as terror bonding, after the notorious case of heiress Patricia Hearst's kidnapping by members of the Symbionese Liberation Army (SLA) in the 1970s where Hearst purportedly joined the captors in an armed bank robbery in support of the SLA, but the number of people who experience the syndrome of identification with their captors is relatively low. The condition is named for the geographic location of a 1973 bank robbery where four hostages were released after six days of terror, only to argue in defense of their captors.
