Complications of mental retardation were studied based on the research
on persons with mental retardation who visited the Social Welfare Center
for Disabilities of Yokohama City from October 1987 to March 1989.
The total number of participants in the study was 377 and consisted of
237 males and 138 females. The youngest of the subjects was 14 years old
while the eldest was 58 and the average age was 22.
1) Epilepsy
The most frequent complication of mental retardation
is epilepsy, which was observed in 106 persons （28．1 %). The frequency
of appearance of epilepsy tends to increase with the increase of the degree
of mental retardation. While the frequency was 53.8% for the persons
with "profound" retardation, the frequency for "severe",
"moderate", "mild" and "borderline" was 23.8%,
26.3%, 18.8% and 7.5%, respectively. In most of the cases, antiepileptic
drugs were dosed. Very few were suffering from epileptic seizure
continuously.
2) Physical Complications
Physical Complications were observed in 55 persons （14.6 %), involving mostly cataract, strabismus or other moderate physical disorder.
3) Emotional Disorder/Schizophrenic Psychosis
For the purpose of this research, "emotional
disorder" refers to an unstable emotional state which has to be treated
with psychotrope. It was observed in 45 persons （11.9%). In
most of the cases, the disturbance was transient.
Schizophrenic psychosis accompanied by hallucination/delusion
was observed in 4 persons （1.1 %), which indicates that the frequency of
the appearance of schizophrenic psychosis for persons with mental retardation
is not different from that for the population in general.
4) Autistic Disorder
For the diagnosis of autistic disorder, the criteria
defined in "DSM III-R" were used. Among the persons in
whom autistic disorder was observed, 88.5% (54 persons) were men and 11.4%
(7 persons) were women, showing the ratio of nearly 7.7:1. This finding
is consistent with the prevailing notion that the frequency of the appearance
of autistic disorder for men is much higher than for women.
It was also found that autistic disorder was observed in 16.2% of the persons with mental retardation. It is near the figure of 19.8% which resulted from the study by Nordin and other researchers1).
While the average intelligence quotient (IQ),
obtained by Takaka-Binet test, for the persons with mental retardation
in whom autistic disorder was observed was 42.4, the IQ for the persons
in whom autistic disorder was not observed was 39.0. Although autistic
disorder was observed in the whole spectrum of persons with mental retardation
from "profound" to "borderline", the assumption by
Smalley and other researchers2) that "the frequency of the appearance of autistic disorder for person
with lower IQ is slightly higher than the person with higher IQ" was
also confirmed by our study.
5) Problems with Adaptive Behavior
For the purpose of this research, "problems
with adaptive behavior" are defined broadly to include from minor
abnormality (such as social adaptive disorder) to serious one (involving
violence). In the cases of persons with mental retardation but without
autistic disorder, as the level of retardation lessens, problems with adaptive
behavior lessen as well. On the contrary, in the cases of persons
with mental retardation and with autistic disorder, as the level of retardation
lessens, the frequency of the appearance of problems with adaptive behavior
increases. In the cases of persons with mental retardation but without
autistic disorder, the frequency of appearance of problems with adaptive
behavior for those in the category of "profound", "severe",
"moderate", "mild" and "borderline" was 12.1%,
6.9%, 8.6%, 1.7% and 0%, respectively. In the cases of persons with
mental retardation and with autistic disorder, the frequency of appearance
of problems with adaptive behavior for those in the category of "profound",
"severe", "moderate", "mild" and "borderline"
was 17.2%,41.4%, 28.5%, 50.0% and 79.3%, respectively.
The frequency of appearance of problems with adaptive
behavior for persons with mental retardation and with autistic disorder
(all categories) was 39%, which is four times higher than that for persons
with mental retardation but without autistic disorder. This leads
to the conclusion that in the administrative management of mental retardation,
persons with mental retardation and with autistic disorder have to be treated
with careful consideration.
References
1)Nordin, V. and Gillberg, C. :Autism spectrum disorders in whildren with
phisical and mental disability or borth I clinical and epidemiological
aspects, Dev. Med. Child Neurol., 38.297-313, 1996
2)Smalley, S, L.. and Asarnow, R, F. :Brief report: cognitive subclinical
markers in autism, J. Autism Dev. Disord., 20,271-278, 1990
(originally published in Journal of disability and medico-pedagogy, Vol.15,2007)