Association between interleukin 1-beta promoter (-511) polymorphism and depressive symptoms in Alzheimer's disease

Depressive symptoms have been associated with raised interleukin 1-beta (IL-1beta) plasma levels. The presence of behavioral and psychological symptoms of dementia (BPSD) in Alzheimer's disease, including depressive symptoms, have been shown to be influenced by common genetic polymorphisms. A common polymorphism in the promoter region of IL-1beta has been linked to altered synthesis of IL-1beta. We hypothesize that this common genetic polymorphism is a risk factor for the appearance of depressive symptoms in AD. A total of 133 subjects, diagnosed as probable AD and 156 controls were genotyped for the -511 variant of IL-1beta. Neither genotype or allele frequencies differed between the AD and control group. However, an allelic association was found between the T variant and the symptoms of depression in AD subjects. Genotypic analysis showed that heterozygotes were three times more likely to develop depressive symptoms than CC homozygotes.