My research is based on the Swedish Twin Registry. With the help of twins a) I study the relative importance of genes and the environment for diseases and different behavioral characteristics, b) examine the effect of genes change over time and in different age c) analyze specific risk and protective factors for disease d) investigating whether there are associations between selected genes and diseases, and e) test whether there are interactions between genes and environmental effects. More recently, I have been working with biomarkers of aging such as telomere length, and epigenetics (methylation). I conduct several studies on "normal" aging, and age-related disorders such as Alzheimer’s and dementia, Parkinson's disease, and late-onset depression.