It is possible that with detailed study, the causes of autism can be found in over a third of cases.
This is postulated by Dr Robert Hennekam and colleagues at the Department of Paediatrics, Emma Children's Hospital, Amsterdam, The Netherlands. Their investigation has shown that an extensive, structured work up yields a diagnosis in at least 20 percent, and possibly up to 36 percent, of adult autistic subjects with mental retardation.
Investigators point out that autism is a chronic and severe neuropsychiatric disorder with an early onset, characterized by qualitative impairments of social interaction, deviant development of language and other communicative skills, delayed cognitive development, and restricted repetitive and stereotyped interests and behaviors.
Three times as many boys as girls are affected, and three quarters of those with autism will have a mental disability. The causes and mechanisms underlying autism vary from chromosome abnormalities, inherited conditions such as metabolic disturbances, infections and teratogenic influences.
Dr Hennekam studied 25 autistic adults with a mental disability to determine why they were autistic. Each patient underwent complete physical examination, ophthalmologic and ENT investigations, EEG studies, karyotyping, brain scans and metabolic investigations including a general urine screen, search for peroxisomal, mitochondrial, glycosylation, and cholesterol metabolism disturbances, and neurological studies.
The researchers found definitive causes for autism in five of the adults, including fetal alcohol syndrome, neonatal disorders, disturbed cholesterol mechanism and genetic defects. Probable causes were found for another four, one of which included an external factor likely to have caused the damage, although the nature of this factor was not known.