Codon 129 polymorphism of prion protein gene in sporadic Alzheimer's disease.

Codon 129 polymorphism of the prion protein gene represents a major genetic risk factor for Creutzfeldt-Jakob disease (CJD). Both CJD and Alzheimer's disease (AD) are brain amyloidoses and it would be possible that codon 129 polymorphism plays a role in the susceptibility to AD. In order to investigate this polymorphism in AD the distribution of polymorphic codon 129 of the PRNP gene in 194 probable AD and 124 controls selected in Italy and 109 neuropathologically verified AD and 58 matched controls recruited in the USA was studied. No significant association was found for the PRNP polymorphism in AD compared to controls either in Probable or in Definite AD series even after stratification for APOE polymorphism. This study does not support a role of PRNP polymorphism as a susceptibility factor for AD.

Apolipoprotein E epsilon4 allele differentiates the clinical response to donepezil in Alzheimer's disease.

The existence of an association between apolipoprotein E (APOE) and Alzheimer's disease (AD) has been reported in several studies. The possession of an ApoE epsilon4 allele is now considered a genetic risk factor for sporadic AD. There has been a growing agreement about the role exerted by the ApoE epsilon4 allele on the neuropsychological profile and the rate of cognitive decline in AD patients. However, a more controversial issue remains about a possible influence of the APOE genotype on acetylcholinesterase inhibitor therapy response in AD patients. In order to address this issue, 81 patients diagnosed as having probable AD were evaluated by a complete neuropsychological test battery at the time of diagnosis (baseline) and after 12-16 months (retest). Patients were divided into two subgroups: (1) treated with donepezil at a dose of 5 mg once a day (n = 41) and (2) untreated (n = 40). Donepezil therapy was started after baseline evaluation. The APOE genotype was determined according to standardized procedures. We evaluated the possible effect of the APOE genotype on the neuropsychological tasks in relation to donepezil therapy. The statistical analysis of the results showed a global worsening of cognitive performances for all AD patients at the retest. Differences in the clinical outcome were analysed in the four subgroups of AD patients for each neuropsychological task. ApoE epsilon4 carriers/treated patients had improved or unchanged scores at retest evaluation for the following tasks: visual and verbal memory, visual attention and inductive reasoning and Mini Mental State Examination. These results indicate an effect of donepezil on specific cognitive domains (attention and memory) in the ApoE epsilon4 carriers with AD. This might suggest an early identification of AD patients carrying at least one epsilon4 allele as responders to donepezil therapy.

The role of brain infarcts and hippocampal atrophy in subcortical ischaemic vascular dementia.

We investigated if, in patients with vascular lesions, the variable that best discriminated demented from non-demented patients was the severity of the vascular pathology or the degree of hippocampal atrophy. A total of 39 patients multiple subcortical infarcts, who could be considered as possible vascular dementia with small vessel pathology, with underwent a neuropsychological study and brain magnetic resonance imaging (MRI) DSM IV criteria supported by neuropsychological data were used to distinguish demented from non-demented patients. The MRI study took into account the degree of hippocampal atrophy (hippocampal height and interuncal distance) and the severity of vascular pathology (number of brain infarcts). The distribution of lesions and a factor analysis showed that hippocampal atrophy is a better predictor of dementia than the number of brain infarcts. Multiple subcortical infarcts alone are probably not able to cause clinical dementia but the presence of vascular lesions increases the expression of concomitant Alzheimer's disease.