Infections were associated with all-cause dementia and dementia subtypes after adjustment for dementia risk factors and comorbidities (age, sex, socioeconomic status, alcohol drinking, smoking, BMI, hypertension, diabetes, and apolipoprotein E genotype) and after exclusion of participants with HIV infection, ischaemic heart disease, cerebrovascular disease, and Parkinson's disease (figure 3; appendix p 23). This evidence concerns the gene APOE and Parkinson disease.