Prevalence and significance of neurocognitive dysfunction in hepatitis C in the absence of correlated risk factors

Neurocognitive morbidity has been reported in individuals with chronic hepatitis C virus (HCV) infection, but the magnitude of such dysfunction in the absence of disease-correlated factors known to affect the central nervous system (e.g., substance abuse, cirrhosis, depression, interferon treatment) and the impact of any such change on functioning is unclear. We investigated a cohort of individuals with HCV, all of whom were carefully screened to exclude relevant comorbidities, to elucidate virus-related changes in the brain using neuropsychological tests and magnetic resonance spectroscopy (MRS). A cohort of 37 patients with chronic HCV infection was culled from 300 consecutive patients presenting to a tertiary care liver clinic. A comparison group of healthy controls (n = 46) was also assessed. Of 10 neurocognitive measures evaluated, the HCV group showed marginally poorer learning efficiency compared with controls; only 13% of patients demonstrated a clinical level of impairment on this test (defined as 1.5 SD below the normative standard). Although patients reported greater levels of fatigue and symptoms of depression, these factors did not correlate with the degree of learning inefficiency. With respect to MRS, the HCV group demonstrated increased choline and reduced N-acetyl aspartate relative to controls in the central white matter. Indicators of liver disease severity did not correlate with either memory or MRS abnormalities. In conclusion, while our findings support an association between hepatitis C and indicators of central nervous system involvement in a cohort of patients carefully screened to eliminate other factors influencing neurocognitive integrity, the clinical significance of these effects is limited.