Pro12Ala polymorphism in PPARgamma2 associated with depression in Chinese nonagenarians/centenarians

The Pro12Ala polymorphism of peroxisome proliferator-activated receptor-gamma (PPARgamma) has been associated with decreased obesity, insulin resistance, type 2 diabetes and other age-associated diseases such as cognitive impairment, hypertension, cancer, osteoarthritis. Each one of these diseases had been linked to depression. Moreover, there is also an association between Pro12 Ala polymorphism in PPAR gamma2 and longevity. The aim of the study was to evaluate the association between Pro12 Ala polymorphism and depression in Chinese nonagenarians and centenarians.

The sample included 697 unrelated Chinese nonagenarians/centenarians (aged between 90-108 years, mean age: 93.5+/-3.35 years; 67.2% women). The Pro12Ala variant was examined using polymerase chain reaction-restriction fragment length polymorphism. Depression was measured with brief 23-item Geriatrics Depression Scale Chinese-edition (GDS-CD).

In this sample, the genotype frequencies of the Pro12Ala polymorphism were 0% Ala12Ala, 9.2% Pro12Ala, 90.8% Pro12Pro and the prevalence of depression was 25.3%. Subjects who were 12Ala carriers had significantly lower prevalence of depression than those who were not 12Ala carriers (14.06 vs. 26.38%, p=0.034). Subjects without depression also had a higher frequency of 12Ala gene than those with depression (5.28 vs. 2.56%, p=0.031). Adjusting for certain clinical factors that may be associated with depression or with 12Ala carriers, multiple logistic regressions showed the 12Ala gene was associated with decreased incidence of depression.

In summary, we found that among Chinese nonagenarians and centenarians, the Pro12Ala polymorphism in PPARgamma2 was associated with depression and that the 12Ala gene may be a factor for decreased depression.