The causes of ORS are unknown. It is thought that significant negative experiences may trigger the development of ORS. These have been considered as two types: key traumatic experiences related to smell, and life stressors present when the condition developed but which were unrelated to smell. In one review, 85% of reported cases had traumatic, smell-related experiences, and 17% of cases had stress factors unrelated to smell. Reported smell-related experiences usually revolve around family members, friends, co-workers, peers or other people making comments about an odor from the person, which causes embarrassment and shame. Examples include accusation of flatulence during a religious ceremony, or being bullied for flatulence such at school, accidental urination in class, announcements about a passenger needing to use deodorant over speaker by a driver on public transport, sinusitis which caused a bad taste in the mouth, mockery about a fish odor from a finger which had been inserted into the person's vagina in the context of a sexual assault, and revulsion about menarche and brother's sexual intimacy. It has been suggested that a proportion of such reported experiences may not have been real, but rather early symptom of ORS (i.e. referential thoughts). Examples of non smell-related stressful periods include guilt due to a romantic affair, being left by a partner, violence in school, family illness when growing up (e.g. cancer), and bullying. The importance of a family history of mental illness or other conditions in ORS is unclear, because most reported cases have lacked this information. In some cases, there has been reported psychiatric and medical conditions in first degree relatives such as schizophrenia, psychosis, alcoholism, suicide, affective disorders, obsessive compulsive disorder, anxiety, paranoia, neurosis, sociopathy, and epilepsy. Sometimes more than one family member had a noteworthy condition. Neuroimaging has been used to investigate ORS. Hexamethylpropyleneamine oxime single-photon emission computed tomography (HMPAO SPECT) demonstrated hypoperfusion of the frontotemporal lobe in one case. That is to say, part of the brain was receiving insufficient blood flow. In another, functional magnetic resonance imaging was carried out while the person with ORS listened to both neutral words and emotive words. Compared to an age and sex matched healthy control subject under the same conditions, the individual with ORS showed more activation areas in the brain when listening to emotionally loaded words. This difference was described as abnormal, but less pronounced as would be observed in the brain of a person with a psychotic disorder.
Olfactory reference syndrome
Olfactory fatigue
Oneirophrenia
Skoptic syndrome
Auditory processing disorder
Uncombable hair syndrome
Auditory neuropathy spectrum disorder
Dual-role transvestism