HIV and Syphilis Co-infection in Dementia Patients in Africa: A Systematic Review and Meta-Analysis of Prevalence Studies

Infectious diseases such as human immunodeficiency virus (HIV) and syphilis are recognized contributors to neurological complications and cognitive impairment. In Africa, where the burden of HIV remains high, coinfections with other sexually transmitted infections may play a significant role in the development or progression of dementia and other neurocognitive disorders. This study aimed to estimate the prevalence of HIV and syphilis coinfection among dementia patients in Africa through a systematic review and meta-analysis. A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-2020) guidelines. Electronic databases including PubMed, Scopus, Web of Science, and Google Scholar were searched for studies published between 2000 and 2025 that reported the prevalence of HIV and/or syphilis among dementia patients in Africa. A random-effects model was used to estimate pooled prevalence. Statistical heterogeneity was assessed using the I² statistic, and publication bias was evaluated using funnel plots and Egger’s regression test. A total of 22 studies involving 8,430 participants met the inclusion criteria. The pooled prevalence of HIV among dementia patients was 21.4% (95% CI: 17.2–25.8), while the pooled prevalence of syphilis was 6.7% (95% CI: 4.1–9.5). The estimated pooled prevalence of HIV–syphilis coinfection among dementia patients was 3.2% (95% CI: 1.9–4.7). Subgroup analyses indicated higher prevalence in East and Southern Africa compared with West Africa. HIV and syphilis coinfection represents a significant but under-recognized contributor to dementia in African populations. Routine screening for sexually transmitted infections among individuals presenting with cognitive impairment may improve early diagnosis and treatment outcomes.