Menendez M.

Secretaria de Neurologia I, Hospital Universitario Central de Asturias,
C/Julian Claveria s/n C.P. 33006 Oviedo, Spain. menendez@aemir.org

Neuropathologically, Alzheimer-type abnormalities are demonstrated in
patients with Down syndrome (DS), both demented and nondemented and
more than a half of patients with DS above 50 years develop Alzheimer's
disease (AD). The apolipoprotein E epsilon4 allele, oestrogen
deficiency, high levels of Abeta1-42 peptide, elevated expression of
BACE2, and valine polymorphism of prion protein gene are associated
with earlier onset of dementia in DS individuals. Advanced AD alone may
be an important risk factor for new-onset seizures in older adults and
age above 60 years is a recognized risk factor for poor outcome from
convulsive and nonconvulsive status epilepticus. DS patients aged over
45 years are significantly more likely to develop Alzheimer's disease
than those less than 45 years and up to 84% demented individuals with
DS develop seizures. Late-onset epilepsy in DS is associated with AD,
while early-onset epilepsy is associated with an absence of dementia.
In AD patients with a younger age of dementia onset are particularly
susceptible to seizures. DS adults with epilepsy score significantly
higher overall on the adaptive behaviour profile. Language function
declined significantly more rapidly in AD patients with seizures and
there is a good correlation between the severity of EEG abnormalities
and cognitive impairment whereas in DS slowing of the dominant
occipital rhythm is related to AD and the frequency of the dominant
occipital activity decreases at the onset of cognitive deterioration.