Cognitive Performance in Asymptomatic Elderly People with Hepatitis C: The Role of Education

Abstract

Background: Neurotropism of the hepatitis C virus (HCV) can be the source of subtle neuropsychological symptoms in non-cirrhotic patients. Age is a risk factor for cognitive impairment (CI). Thus, asymptomatic elderly people who carry HCV might be at a greater risk of CI. Education can influence test performance.

Objectives: (1) To verify whether elderly people with HCV performed poorer than controls on cognitive tests. (2) To analyze how education affects performance. (3) To verify whether the extent of the effect of education on performance depends on the group (HCV vs. controls) and the type of cognitive test.

Methods: Asymptomatic HCV carriers older than 60 years (n = 41) were matched with 41 corresponding controls. All participants performed the following tests: Mini-Cog, Mini Mental State Examination, clock drawing test (CDT), and verbal fluency.

Results: (1) There were no significant differences in cognitive performance between the two groups. (2) Higher education was always associated with better performance. (3) There was a significant group difference in the slopes of the regression lines between years of education and CDT performance. No differences were found for the other three tests.

Conclusion: Considering the scores on the CDT, the rate of improvement in performance when schooling increases is higher in HCV carriers.

Keywords: chronic hepatitis C; clock drawing test; cognitive reserve; education; elderly; literacy; mental status tests; viral hepatitis.

Figure 1

Effect of education level on cognitive performance in controls and HCV carriers: Bar graphs displaying the mean ± standard error per group (controls or HCV), separated by educational level (high or low) for each test. The diagrams indicate that subjects with a higher education level (H) always perform better than those with a lower education level (L), irrespective of the group (controls or HCV). The statistical analyses show that differences reach significance in the MMSE and VFT independent of the subjects’ group. Although the performances in the Mini-Cog are better in higher-educated participants in both groups, the differences are not statistically significant. For the CDT, the effect of education on performance only reaches statistical significance in the HCV group. HCV, hepatitis C virus; * p-value < 0.05; NS, non-significant; low education indicates <8 years of formal education; high education indicates ≥8 years of formal education.

Figure 2

Regression lines showing the relationship between cognitive performance and years of education. Regression lines between Z-scores of cognitive tests (dependent variables) are on the y-axis, and years of education (independent variables) are on the x-axis for each group (control and HCV groups are represented in blue and yellow, respectively). Note that there are no group differences in the slopes of the regression lines for the Mini-Cog, VFT, and MMSE. In contrast, for the CDT, the slope of the regression line is significantly higher in the HCV group as compared to the control group (p < 0.05). CDT, clock drawing test; MMSE, Mini Mental State Examination; VFT, verbal fluency test (category: animals); HCV, hepatitis C virus; p, proof value.