For many years, Down's syndrome (D.S) is known to be one of the best
model of premature ageing of the whole organism particulary with brain lesions
quite similar to those observed in senile dementia of Alzheimer's type
Some epidemiological studies have shown that relatives of S.D.A.T.
exhibit an excess of both dementing illness and D.S. A possible relationship
between those two diseases has been hypothesed. The aim of this study is to
test wether there is an excess of senile dementia cases in D.S. relatives or
some particular mortality trends in those families.
We conducted by interview of parents a case-control study in families of
DS children with trisomy 21 diagnostic proved by a caryotype. A control group
was constituted with families of children referred to the salve hospital for
We have currently recruited 132 families of DS children. We obtained
reliable data on the medical history on 517 out of 528 grandparents and 764 out
of 1056 great-grand parents. Investigation of senile dementia cases was
restricted to those who had reached the age of 60 : 365 grandparents and 573
great-grandparents. A total of 25 probable senile dementia with progressive
course was found (2.7 %) : 4 in grandparents (1.1 %), 21 in great-grandparents
(3.7 %). However, out of 12 Parkinson disease observed in these sample (1.1 %),
four cases were associated with dementia.
A total sample size of about 200 DS cases is expected. The proportion of
senile dementia observed in these families will be compared to control