Nottingham (England): Most people are familiar with psychiatric disorders such as schizophrenia and bipolar disorder, but some conditions are so rare that many psychiatrists won't come across a single case in their professional lives. Here I present five of the rarest and strangest syndromes known to psychiatry.
1. Fregoli syndrome:Fregoli syndrome is where someone believes that different people are in fact the same person who just changes their appearance. People with this syndrome often feel persecuted by those they believe to be in disguise. The disorder is named after Leopoldo Fregoli, an Italian theatre actor who was known for his remarkable ability to quickly change his appearance while on stage.
Fregoli syndrome typically occurs with other mental disorders, such as bipolar disorder, schizophrenia and obsessive-compulsive disorder. It can also be caused by brain injury and use of the drug levodopa in the treatment of Parkinson's disease. A review in 2018 found that fewer than 50 cases worldwide had been reported since the condition was first described. However, a more recent study (2020) reported an incidence of 1.1% among patients following a stroke, so certainly more than 50 cases but still very rare. There is no known cure for Fragoli syndrome, but treatment with antipsychotic drugs may lessen the symptoms.
2. Cotard's syndrome:Cotard's syndrome, also known as walking corpse syndrome, is where people hold the delusional belief that they are dead and do not exist. Others believe that body parts are missing. The syndrome is named after the 19th-century French neurologist Jules Cotard, who first described the condition in 1882.
Schizophrenia, depression and bipolar disorder are risk factors for Cotard's syndrome. However, it has also been reported as a rare side-effect of the anti-viral drug acyclovir. The syndrome is thought to originate from a disconnection between the areas of the brain that recognise faces and the areas that associate emotional content with such facial recognition. This rare condition is usually treated with antidepressants, antipsychotics, and mood stabilisers, as well as electroconvulsive therapy.
3. Alien hand syndrome:Alien hand syndrome is one of the strangest neurological disorders. It is where a person's hand appears to have a mind of its own and acts autonomously, and where the person feels as though their hand doesn't belong to them. This syndrome was first identified in 1908 but was not clearly defined until the early 1970s. The term alien hand syndrome was coined by Joseph Bogen, an American neurophysiologist, to describe a curious wayward behaviour occasionally seen during recovery from certain types of brain surgery.
People with alien hand syndrome typically have sensory processing disorders and dissociate themselves from the actions of their hand. Research indicates that people with the syndrome often personify the alien hand, and may believe it is possessed by some other spirit or alien life form.