The likelihood of developing dementia increases with age in the general US population, as well as in people living with HIV in the US. However, a new study suggests that people with HIV aged over 75 may experience a higher prevalence of dementia compared to the general population—with the largest gap seen in women.
Growing older is the highest risk factor for developing dementia — when cognitive impairment becomes severe enough to affect a person’s ability to perform everyday tasks. For example, the prevalence of Alzheimer’s disease and related dementia doubles every five years after one reaches the age of 65. Previous studies have linked risk factors for developing dementia—including cardiovascular disease, high blood pressure, diabetes, and social isolation—as being more likely in people with HIV. Furthermore, the fastest-growing age group of people with HIV in the US is people over 65 years of age. Yet, few studies have directly compared the prevalence of dementia in people with HIV to those without the virus.
A study authored by Dr Xiaoying Yu of the University of Texas Medical Branch analysed data from the US Medicare system to shed more light on this question. The researchers collected data from all 50 states and compared eight groups comprised of two genders (male and female) and four age groups (65 to 69, 70 to 74, 75 to 79, and over 80 years old). The researchers then assessed how the prevalence of dementia, as identified by specific diagnosis codes, changed in people with and without HIV among the eight groups between 2007 and 2019.
The Medicare dataset included more than 87,000 people with HIV and over two million people without HIV who had been assessed for Alzheimer’s disease or another type of dementia over at least a one-year period. While the overall cohort was mostly female (56%), it contained more men living with HIV than without HIV (66% versus 44%). Among the people with HIV, the cohort was relatively diverse, and the mean age at first entry into the study was 73 years.
When adjusting for demographics and comorbidities, there was little difference in dementia prevalence between participants with and without HIV in the younger age groups. For example the adjusted prevalence remained fairly similar for men with or without HIV in the age groups of 65 to 69 (about 4% prevalence) and 70 to 74 (about 5%). In the 75 to 79 age group, a small but not statistically significant gap emerged showing adjusted prevalence in men without and with HIV of around 8% to 9% respectively. Above 80 years old, a statistically significant gap widened, showing adjusted prevalence increasing from 2007 to 2019 and ranging from about 20% to 25% for men without HIV and about 20% to 30% for men living with HIV.
For women living with HIV compared to other women, the increase in adjusted prevalence of dementia was even more prominent in the older age categories. Differences in adjusted prevalence among women in the first two age groups were not statistically significant between those with and without HIV showing values ranging from 4% to 5% (65 to 69) and 5% to 7% (70 to 74). A statistically significant gap emerged in the age group of 75 to 79, showing about 8% of women without HIV were diagnosed with dementia and between 10 and 12% of those living with HIV. Above 80 years, the gap in adjusted prevalence of dementia between 2007 and 2019 was far wider—ranging from about 25% to 32% in women without HIV and from about 26% to nearly 40% in women living with HIV.
The study did not reveal any significant differences in comorbidities linked to dementia between people with and without HIV.
These results only indicate an association exists. They do not provide evidence that HIV causes a higher likelihood of developing dementia while ageing. This study also did not account for socioeconomic factors such as education levels and income, or HIV factors such as years living with HIV, viral loads, and CD4 levels. Other limitations include possible errors in Medicare data and an inability to analyze specific types of dementia, such as that specifically related to Alzheimer’s disease.
Nonetheless, the analysis shows that the entire study population was more likely to develop dementia as it grew older, but those with HIV—especially older women—showed a higher degree of susceptibility. Based on the findings, the researchers recommend clinical guidelines that integrate dementia screening as part of their routine care to better serve people with HIV as they age.
Xiaoying Y et al. Dementias Among Older Males and Females in the U.S. Medicare System With and Without HIV. Journal of Acquired Immune Deficiency Syndromes 93(2): 107-115, 2023.