Investigation of the Component Processes Involved in Verbal Declarative Memory Function in Bipolar Disorder: Utility of the Hopkins Verbal Learning Test-Revised

Evidence suggests that standard learning and recall indexes are sensitive markers of verbal declarative memory ability in bipolar disorder (BD), but no study has examined performance across the full range of component process measures on the Hopkins Verbal Learning Test (HVLT-R) in a BD cohort. As the HVLT-R is part of a widely used battery of cognitive functioning backed by the U. S. Federal Drug Administration as the accepted battery for use in pro-cognitive trials assessing cognitive-enhancing drugs in the related disorder schizophrenia, estimating the utility of its measures in BD is important. Forty-nine BD patients and 51 healthy controls completed the HVLT-R, which was scored for 13 variables of interest, across 4 indices: recall and learning, recognition, strategic organization, and errors. BD patients had greater difficulty in learning the HVLT-R word list compared to controls. They also demonstrated impairment in delayed recall/recognition. There were no differences between the groups in terms of their slope of learning, retrieval index, retention percentage, semantic or serial clustering, errors, or level of retrieval. This pattern was consistent across symptomatic and euthymic patients. The HVLT-R has some utility in characterizing the component processes involved in memory function in BD, such that memory impairments appear to be attributable to deficient encoding processes during the acquisition phase of learning. In the case of planning pro-cognitive clinical trials, the encoding deficits in BD observed here may be sensitive enough to potentially respond to medications designed to enhance the verbal memory performance.