There was a great improvement in CHC prognosis after the introduction of combination therapy with peg-IFNalpha/RBV. The highest treatment drop-out rate is related to interferon-induced mental health problems including confusional states, depressive episodes and manic conditions. The literature concerning working memory abnormalities observed during peg-IFNalpha/RBV therapy of CHC patients was scarce.

The aim of the study was to describe the probable connection between peg-IFNalpha/RBV treatment and the development of cognitive functions' disturbances in CHC patients.

Forty-seven CHC patients were consecutively enrolled in the study. They were arbitrarily divided into two groups: experimental and control consisting of 26 and 21 participants, respectively. Experimental group patients were given peg-IFNalpha/RBV treatment for 48 weeks in standard doses recommended by manufacturers. Control group patients did not receive the above treatment. Both groups underwent neuropsychological examination at the beginning and after 12 weeks of treatment or observation. Neuropsychological evaluation consisted of Stroop Color Word Test (SCWT) and Trail Marking Test (TMT) - instruments used for the assessment of the higher cognitive functions like working memory.

Cognitive performance measured by means of SCWT and TMT decreased significantly in the experimental group after 12 weeks of combination therapy. No significant deterioration was seen in the control group over the period of observation.

The findings suggest that peg-IFNalpha/RBV therapy of CHC patients is connected with the deterioration in cognitive functioning including working memory. The above changes may be the effect of interferon alpha-induced neurotransmission abnormalities in the limbic system, dorso-lateral prefrontal cortex and anterior cingulate cortex.