Dissociation of remote and anterograde memory impairment and neural correlates in alcoholic Korsakoff syndrome

Abstract

Alcoholic Korsakoff's syndrome (KS) is marked by remote memory impairment together with characteristic profound anterograde memory deficits. Despite previous studies of memory processes in KS, questions remain regarding the nature and severity of these impairments and identification of brain systems that underlie these different memory impairments. This study examined remote and anterograde memory function in 5 KS patients in comparison with 8 patients with Alzheimer's disease (AD) and 24 normal control subjects (NC). In addition, relationships between memory performance and regional brain volumes were examined in the KS group. Overall, the KS group showed severe impairment on both remote and anterograde memory measures, performing at the level of the AD group on most measures. Differences were observed on the pattern of temporal gradient for verbal recognition, with KS exhibiting a more steeply graded rate of decline over the most recent period examined. Severity of the remote memory deficit in KS was not associated with severity of anterograde memory deficit. Examination of brain structure-function relationships in the KS subjects revealed that photo naming of remote historical information was related to posterior cortical white matter volumes but not hippocampal volumes; sequencing was related to prefrontal but not hippocampal volumes. By contrast, a measure of anterograde memory for nonverbal visual material showed a relationship to hippocampal but not regional cortical white matter volumes. This set of dissociations, which parallels that observed in our earlier study of AD, is now documented in KS and provides further evidence that these separate cortical and limbic brain systems are principal neural substrates of the remote and anterograde memory and sequencing deficits in KS.

Salient cues improve prospective remembering in Korsakoff's syndrome

“…In line with our expectations and ample evidence of episodic memory and executive functions deficits (e.g., Brion et al, 2014;Fama, Marsh, et al, 2004;Wester, Leenders, Egger, & Kessels, 2013), individuals with Korsakoff's syndrome showed poorer PM (23% and 45% hits on the low and high salient condition, respectively) than those with chronic alcoholism. In general, Korsakoff patients performed at a low level indicating a severe PM deficit, but importantly their performance significantly differed from zero.…”

What does a comparison of the alcoholic Korsakoff syndrome and thalamic infarction tell us about thalamic amnesia?

“…Interestingly, these findings were consistent with those in an earlier study (Kopelman, 1991), which showed that performance on executive tests could predict 68.5% of the variance in Korsakoff patients on autobiographical and remote memory tasks, compared with only 21% of variance predicted by performance on anterograde memory tests. Fama et al (2004) carried out a related study, examining the performance of five Korsakoff patients on a test of Famous Presidents. They also found that remote memory impairment was not correlated with the severity of anterograde memory impairment.…”

Visuoperceptual Learning in Alcoholic Korsakoff Syndrome

“…These KS patients were a subset of those examined in our earlier studies (Fama et al, 2004a;Shear et al, 1996;Sullivan and Marsh, 2003) and had Wechsler Memory Scale-Revised (Wechsler, 1987) scores ranging from 34 to 45 points below their respective National Adult Reading Test (NART) scores. These differences exceeded the 1.5 SD difference criteria to confirm the presence of anterograde amnesia (Oscar-Berman et al, 1993;Weiskrantz, 1985) (Table 1).…”

“…Memory deficits in KS also involve components of remote memory (Kopelman, 1995;Kopelman et al, 1999;Squire et al, 2001) possibly arising from damage to posterior cortical systems (Fama et al, 2004a). In contrast to explicit memory processes for which learning is assessed by conscious recall or recognition of specific information encountered previously, implicit memory processes are assessed by modification of responses by previously encountered stimuli, without necessarily having conscious knowledge of learning (Graf and Schacter, 1985;Tulving and Schacter, 1990;Verfaellie and Keane, 2002).…”