Cognitive reserve is a resilience factor for cognitive dysfunction in hepatic encephalopathy

Cognitive Reserve (CR) modulates symptoms of brain disease. The aim of this study was: to evaluate the effect of CR on cognition in cirrhosis and on the mismatch between cognitive and neurophysiologic assessment of hepatic encephalopathy (HE). Eighty-two outpatient patients with cirrhosis without overt HE were studied [73% males; age: 62 (54-68) (median, interq. range) yrs.; education: 8 (6-13) yrs.]. The Psychometric Hepatic Encephalopathy Score (PHES) was used as cognitive measure of HE. The spectral analysis of the electroencephalogram (EEG) was used as neurophysiologic measure of HE. The CR was assessed by the CR Index (CRI), which was measured by the CRI questionnaire (CRIq) (http://cri.psy.unipd.it). The PHES was altered in 28% of patients and the EEG in 41%. Altered PHES was related to the severity of cirrhosis as assessed by Child-Pugh classification (R = 0.31, p < 0.005). Patients with maintained PHES had higher CRI than those with altered PHES (CRI = 100 +/- 20 vs. 88 +/- 12 vs., p < 0.01), but not the ones with normal EEG compared to those with abnormal EEG (CRI = 96 +/- 17 vs. 98 +/- 17 vs. p: n.s.).The PHES, but not the EEG, was found to be related to the CRI (r = 0.35, p < 0.01). The mismatch between cognitive and neurophysiologic evaluation of non-overt HE (the ratio between PHES and the mean dominant frequency -MDF- of the EEG i.e., cognitive performance normalized by EEG speed) was found to be correlated to the CRI (r = 0.36, p < 0.005). CR is a resilience factor for cognitive dysfunction in cirrhosis, and is easily measurable by CRIq.