It is unclear what causes<unk> , though several theories have been proposed. Early studies showed evidence that there may be an interhemispheric transfer deficit among people with<unk> ; that is, the emotional information from the right hemisphere of the brain is not being properly transferred to the language regions in the left hemisphere, as can be caused by a decreased corpus callosum, often present in psychiatric patients who have suffered severe childhood abuse. A neuropsychological study in 1997 indicated that<unk>  may be due to a disturbance to the right hemisphere of the brain, which is largely responsible for processing emotions. In addition, another neuropsychological model suggests that<unk>  may be related to a dysfunction of the anterior cingulate cortex. These studies have some shortcomings, however, and the empirical evidence about the neural mechanisms behind<unk>  remains inconclusive. French psychoanalyst Joyce McDougall objected to the strong focus by clinicians on neurophysiological explanations at the expense of psychological ones for the genesis and operation of<unk> , and introduced the alternative term "disaffectation" to stand for psychogenic<unk> . For McDougall, the disaffected individual had at some point "experienced overwhelming emotion that threatened to attack their sense of integrity and identity", to which they applied psychological defenses to pulverize and eject all emotional representations from consciousness. A similar line of interpretation has been taken up using the methods of phenomenology. McDougall has also noted that all infants are born unable to identify, organize, and speak about their emotional experiences (the word infans is from the Latin "not speaking"), and are "by reason of their immaturity inevitably<unk> ". Based on this fact McDougall proposed in 1985 that the<unk>  part of an adult personality could be "an extremely arrested and infantile psychic structure". The first language of an infant is nonverbal facial expressions. The parent's emotional state is important for determining how any child might develop. Neglect or indifference to varying changes in a child's facial expressions without proper feedback can promote an invalidation of the facial expressions manifested by the child. The parent's ability to reflect self-awareness to the child is another important factor. If the adult is incapable of recognizing and distinguishing emotional expressions in the child, it can influence the child's capacity to understand emotional expressions. Molecular genetic research into<unk>  remains minimal, but promising candidates have been identified from studies examining connections between certain genes and<unk>  among those with psychiatric conditions as well as the general population. A study recruiting a test population of Japanese males found higher scores on the Toronto<unk>  Scale among those with the 5-HTTLPR homozygous long (L) allele. The 5-HTTLPR region on the serotonin transporter gene influences the transcription of the serotonin transporter that removes serotonin from the synaptic cleft, and is well studied for its association with numerous psychiatric disorders. Another study examining the 5-HT1A receptor, a receptor that binds serotonin, found higher levels of<unk>  among those with the G allele of the Rs6295 polymorphism within the HTR1A gene. Also, a study examining<unk>  in subjects with obsessive-compulsive disorder found higher<unk>  levels associated with the Val/Val allele of the Rs4680 polymorphism in the gene that encodes Catechol-O-methyltransferase (COMT), an enzyme which degrades catecholamine neurotransmitters such as dopamine. These links are tentative, and further research will be needed to clarify how these genes relate to the neurological anomalies found in the brains of people with<unk> . Although there is evidence for the role of environmental and neurological factors, the role and influence of genetic factors for developing<unk>  is still unclear. A single large scale Danish study suggested that genetic factors contributed noticeably to the development of<unk> . However, such twin studies are controversial, as they suffer from the "equal environments assumption" and the "heritability" estimates in no way correspond to actual DNA structures. Traumatic brain injury is also implicated in the development of<unk> , and those with traumatic brain injury are six times more likely to exhibit<unk> .
Alexithymia
Automatism 
Phobia
Body integrity dysphoria
Automatic behavior
Morbid love
Hyperreligiosity
Musical anhedonia