Hepatitis C doesn't affect cognitive function of women, but some evidence HIV does

Infection with hepatitis C does not affect the cognitive performance of women with or at risk of HIV, according to data from the Women’s Interagency HIV Study (WIHS) published in the online edition of the Journal of Acquired Immune Deficiency Syndromes.

“We were unable to show a significant association between the presence of HCV [hepatitis C virus]…and performance on our cognitive battery nor that there is an interaction between HIV and HCV in their effect on cognitive function,” write  the authors.

However, their was some evidence that infection with HIV had an impact on cognition.

A number of earlier studies have suggested that hepatitis C-infected individuals have an increased risk of neurocognitive impairments. Moreover, replicating virus has been found in the brains of patients with the infection. It has also been suggested that co-infection with HIV and hepatitis C could have a worse impact on cognitive function than either virus alone.

Women have been unrepresented in research exploring the impact of hepatitis C on cognition. Therefore, investigators from the WIHS designed a study involving 1338. Just under a fifth (18%) had detectable hepatitis C virus and 67% were infected with HIV.

“To our knowledge this cohort for our study is over twice as large as any previously reported study of the effects of HCV and HIV on cognition,” note the investigators.

The patients were divided into six groups:

• Negative for both HIV and hepatitis C RNA (392 individuals).

• HIV-negative/hepatitis C RNA-positive (42 individuals).

• HIV-positive/hepatitis C RNA-negative (480 individuals).

• AIDS/hepatitis C RNA-negative (241 individuals).

• AIDS/hepatitis C RNA-positive (88 individuals)

The patients had a battery of four tests to assess their cognitive function. The results were controlled for age, ethnicity, depression, liver disease status and current or past drug and alcohol abuse, all of which have been shown to affect cognitive function.

There were significant differences between the patients according to their hepatitis C and/or HIV-infection status.

Individuals infected with hepatitis C were a significant nine years older than women who did not have hepatitis C (p < 0.001). Rates of injecting drug use were also significantly higher among the women with hepatitis C (85% vs. 12%), and hepatitis C-infected women were also significantly more likely to report recent use of cocaine (p < 0.001).

As expected, liver function was significantly poorer in those infected with hepatitis C, and the women with an AIDS diagnosis had lower CD4 cell counts than other individuals (p = 0.001).

After controlling for potential confounders, the investigators failed to find any association between hepatitis C viraemia and cognitive performance.

In their first set of analysis, they established a significant connection between poorer liver function and poorer cognitive function (p < 0.001). However, this relationship disappeared after controlling for factors such as age, ethnicity, depression and general mental health.

Nevertheless, infection with HIV was associated with impaired speed of information processing and perceptual motor ability (p < 0.001).

The investigators do not regard their findings as definitive: “The question of whether HCV has a direct effect on cognition will require future studies with a complete neuropsychological batter, a large control group and a large group of HCV-mono-infected subjects.” They also believe that such studies would need “a cohort that includes both men and women.”