Association between human herpesvirus 6 (HHV-6) and cognitive function in the elderly population in Shenzhen, China

Aim: Human herpesvirus 6 (HHV-6) is neurophilic, and its relationship with Alzheimer’s disease (AD) remains controversial. This study aimed to examine the relationships between HHV-6 and cognitive abilities in elderly people aged 60 years or above from communities in Shenzhen. Methods: We recruited participants from 10 community health service centers in Shenzhen. Participants were divided into case and control groups according to Mini-Mental State Examination (MMSE) scale standards and were included in this study with 1:1 matching based on sex and age (± 3 years). The HHV-6 gene was detected by real-time fluorescent quantitative PCR, and the HHV-6 copy number was quantified. Results: A total of 580 participants (cases, n= 290; controls, n= 290), matched for gender and age was included in this study. A positive HHV-6 test was not associated with a significant difference in global cognitive performance (OR_adjusted= 1.651, 95% CI = 0.671–4.062). After adjusting for gender, age, education, Pittsburgh Sleep Quality Index (PSQI) score, homocysteine (Hcy) and glycosylated hemoglobin (HbA1c), the results of multiple linear regression showed that there was a statistically negative correlation between HHV-6 copy number and orientation (β_adjusted= −0.974, p= 0.013), attention and calculation (β_adjusted= −1.840, p< 0.001), and language (β_adjusted= −2.267, p< 0.001). The restricted cubic spline (RCS) model results showed that there was a nonlinear dose–response relationship between HHV-6 log10-transformed copies and orientation (p_overall= 0.003, p_nonliner= 0.045), attention and calculation (p_overall< 0.001, p_nonliner< 0.001), and language (p_overall< 0.001, p_nonliner= 0.016). Conclusions: HHV-6 infection significantly associated with orientation, attention and calculation, and language in elderly individuals.