These deficits were less severe than those seen in similar aged children with a diagnosis of MS.Another study compared nineteen children with a history of ADEM, of which 10 were five years of age or younger at the time (average age 3.8 years old, tested an average of 3.9 years later) and nine were older (mean age 7.7y at time of ADEM, tested an average of 2.2 years later) to nineteen matched controls. Scores on IQ tests and educational achievement were lower for the young onset ADEM group (average IQ 90) compared to the late onset (average IQ 100) and control groups (average IQ 106), while the late onset ADEM children scored lower on verbal processing speed. Again, all groups means were within one standard deviation of the controls, meaning that while effects were statistically reliable, the children were as a whole, still within the normal range. There were also more behavioural problems in the early onset group, although there is some suggestion that this may be due, at least in part, to the stress of hospitalization at a young age. Research
The relationship between ADEM and anti-MOG associated encephalomyelitis is currently under research. A new entity called MOGDEM has been proposed.About animal models, the main animal model for MS, experimental autoimmune encephalomyelitis (EAE) is also an animal model for ADEM.
Exposure to vaccines: The only vaccine proven related to ADEM is the Semple form of the rabies vaccine, but hepatitis B, pertussis, diphtheria, measles, mumps, rubella, pneumococcus, varicella, influenza, Japanese encephalitis, and polio vaccines have all been implicated. The majority of the studies that correlate vaccination with ADEM onset use small samples or case studies. Large scale epidemiological studies (e.g., of MMR vaccine or smallpox vaccine) do not show increased risk of ADEM following vaccination. An upper bound for the risk of ADEM from measles vaccination, if it exists, can be estimated to be 10 per million, which is far lower than the risk of developing ADEM from an actual measles infection, which is about 1 per 1,000 cases. For a rubella infection, the risk is 1 per 5,000 cases. Some early vaccines, later shown to have been contaminated with host animal CNS tissue, had ADEM incident rates as high as 1 in 600. In rare cases, ADEM seems to follow from organ transplantation. Diagnosis
ADEM term has been inconsistently used at different times. Currently, the commonly accepted international standard for the clinical case definition is the one published by the International Pediatric MS Study Group, revision 2007.Given that the definition is clinical, it is currently unknown if all the cases with ADEM are positive for anti-MOG autoantibody, but in any case, it seems strongly related to ADEM diagnosis. Differential diagnosis
Multiple sclerosis
While ADEM and MS both involve autoimmune demyelination, they differ in many clinical, genetic, imaging, and histopathological aspects.