Study of lipids, insulin metabolism, and paraoxonase-2-311 polymorphism in patients with different subtypes of Alzheimer's disease (translated version).

Objective: To investigate the characteristics of blood lipids, insulin metabolism, and paraoxonase-2-311 (PON2-311) polymorphism among patients with Alzheimer's disease with different types of dementia. Methods: A total of 84 patients with Alzheimer's disease, according to the National Institute of Neurological and Communicative Disorders and Stroke, and the Alzheimer's Disease and Related Disorders Association clinical criteria for 'possible Alzheimer's disease', and with no family history of the condition, were enrolled. They were then categorised into 3 groups (senile dementia, presenile dementia, and mixed dementia) according to the diagnostic criteria of the Chinese Classification of Mental Disorders, third edition. Polymerase chain reaction-restriction fragment length polymorphism analysis was used to determine the presence of PON2-311 polymorphism. Serum cholesterol, triglycerides, highdensity lipoprotein, low-density lipoprotein, and fasting blood sugar were measured. Fasting plasma insulin was measured using chemiluminescence. The basal-state method was used to assess insulin resistance expressed as insulin sensitivity index. The cognitive rating scale of the Mini-Mental State Examination, Activities of Daily Living scale, and Hachinski Ischemic Scale were used to establish the clinical features and severity of cognitive impairment. Differences in PON2-311C/S polymorphism, serum insulin, blood glucose, blood lipids, and neuropsychological score were analysed. Results: The serum triglyceride and cholesterol levels of the presenile dementia group were significantly higher than those of the senile and mixed dementia groups (p < 0.01). The high-density lipoprotein level of the senile dementia group was significantly higher than that of the mixed dementia group (p < 0.05). The serum insulin level of the presenile dementia group was significantly higher than that of the senile (p < 0.05) and mixed dementia groups (p < 0.01). There were no significant differences in distribution of the PON2-311 genotypes C/C, C/S, and S/S between the senile and mixed dementia groups, and no significant differences in C-allele and S-allele frequency between the 2 groups. Conclusions: The differences in serum triglycerides, cholesterol, high-density lipoprotein, and insulin levels between Alzheimer patients with senile, presenile, and mixed dementia found in this study suggest that patients with presenile dementia should monitor their lipid and insulin metabolism. No significant differences were found for PON2-311 genotypes or allele frequencies in patients with dementia due to Alzheimer's disease.