Preserved intellectual functioning in Korsakoff’s syndrome? Actual and premorbid intelligence in patients with major or mild alcohol-related cognitive disorder

Objective: Although alcoholic Korsakoff patients show profound cognitive impairments (including amnesia), intellectual function has typically been assumed to be preserved. Based on more recent models on intelligence, however, it can be hypothesized that although preserved verbal or crystallized abilities may be expected in Korsakoff patients, fluid reasoning may be significantly reduced. Aim of this study was to gain insight in intelligence profiles of patients with alcohol-related cognitive disorders with and without Korsakoff's syndrome (KS).Method: Test performance on the Wechsler Adult Intelligence Scale - Fourth Edition (WAIS-IV) and the National Adult Reading Test (NART) was assessed in 34 patients diagnosed with KS, 40 patients with chronic alcohol-related cognitive disorder without Korsakoff's syndrome (ALC), and 47 non-alcoholic psychiatric controls (non-ALC).Results: Analysis revealed significant lower WAIS-IV Full-Scale IQ scores compared to the estimated premorbid NART-IQ in both groups with alcohol-related cognitive disorders (KS and ALC). With respect to the index scores, KS patients performed worse than non-ALC patients on the Perceptual Reasoning and Processing Speed Indices. Performance on the Verbal Comprehension and Working Memory Indices did not differ between groups.Conclusion: Not all aspects of intelligence are preserved in Korsakoff's syndrome and implications of assessment of intellectual function in patients with alcohol-use disorder are discussed.