Korsakoff syndrome and altered pain perception: a search of underlying neural mechanisms

OBJECTIVES

Patients with Korsakoff syndrome (KS) may have a diminished pain perception. Information on KS and pain is scarce and limited to case descriptions. The present study is the first to investigate the underlying neural mechanisms of altered pain perception in patients with KS more systematically.

METHODS

We conducted a literature search on neural correlates of pain perception in other neurocognitive disorders in which extensive research was done.

RESULTS

The brain areas that are affected in KS showed considerable overlap with the neural correlates of pain perception in other neurocognitive disorders. We discussed which different aspects of disturbed pain perception could play a role within KS, based on distinct neural damage and brain areas involved in pain perception.

CONCLUSIONS

Combining current knowledge, we hypothesize that diminished pain perception in KS may be related to lesioned neural connections between cerebral cortical networks and relays of mainly the thalamus, the periaqueductal gray, and possibly lower brain stem regions projecting to the cerebellum. Based on these neural correlates of altered pain perception, we assume that increased pain thresholds, inhibition of pain signals, and disturbed input to cerebral and cerebellar cortical areas involved in pain processing, all are candidate mechanisms in cases of diminished pain perception in KS. We recommend that clinicians need to be alert for somatic morbidity in patients with KS. Due to altered neural processing of nociceptive input the clinical symptoms of somatic morbidity may present differently (i.e. limited pain responses) and therefore are at risk of being missed.

"Cinderella was attacked by the big bad wolf, but the police saved her": intrusions and confabulations on story recall in Korsakoff's syndrome and alcohol-related cognitive impairments

BACKGROUND

The relation between confabulations and intrusions in patients with Korsakoff's syndrome (KS) and patients with alcohol-related cognitive impairments (ARCI) remains under debate. This study examines (1) differences in the production of confabulations and intrusions between patients with KS and ARCI, (2) whether an altered fairy tale induces more intrusions, and (3) whether different types of intrusions were significantly related to confabulations.

METHODS

Twenty-three patients with KS and twenty-two patients with ARCI recalled three different types of stories: a novel story, a fairy tale, and a modified fairy tale. Different types of intrusions were correlated with confabulation measures.

RESULTS

Patients with KS produced more intrusions in the modified fairy tale condition than patients with ARCI, but these were unrelated to confabulations. Only unrelated intrusions were related to provoked confabulations.

CONCLUSIONS

The results of this study indicate that researchers and clinicians must be aware that in general, intrusions on memory tests should not be interpreted as confabulations. Especially spontaneous confabulations appear to be something completely different from intrusions on any type of story recall. When measuring confabulations it is crucial to use validated instruments.

Nonalcoholic Wernicke-Korsakoff Syndrome Resulting From Psychosis

ABSTRACT

Wernicke encephalopathy (WE) results from thiamine deficiency. If undiagnosed or inadequately treated, WE evolves into Korsakoff syndrome (KS). We herein report a case of nonalcoholic Wernicke-Korsakoff syndrome (WKS) that resulted from malnutrition due to psychosis in a 42-years-old male patient. Thiamine deficiency was secondary to severe malnourishment due to poisoning delusions and daily life disorganization in a patient with previously unrecognized schizophrenia. Besides the presence of WE's classic triad of signs, brain magnetic resonance imaging showed also typical thalamic lesions. Furthermore, the patient also presented anterograde and retrograde amnesia, executive dysfunction, and confabulations, compatible with KS being already present. Intravenous treatment with thiamine was given for 37 days. Improvement in cognitive functions and brain imaging alterations was evident. Nevertheless, persistent WKS deficits were present. This case highlights the multiplicity of etiologies of WKS, namely, psychiatric, and its debilitating consequences if not promptly recognized and treated.

Unraveling Apathy in Korsakoff Syndrome Patients Receiving Long-Term Care With and Without Cerebrovascular Comorbidity

BACKGROUND

Korsakoff syndrome (KS) is a severe neuropsychiatric disorder caused by acute deficiency of vitamin B1 and concomitant alcoholism. Patients with KS are particularly vulnerable for cerebrovascular comorbidity. KS is characterized by cognitive and neuropsychiatric symptoms, one of which is apathy. Apathy is a pathological lack of goal-directed behaviors, goal-directed cognitions, and goal-directed emotions. Cerebrovascular accidents are known to carry a risk for developing apathy. Apathy has a dramatic effect on the autonomy and daily lives of patients suffering from this condition.

METHODS

We assessed general apathy and related subconstructs in fifteen patients with KS, fifteen patients with KS and cerebrovascular comorbidity who reside in a 24-hour care facility, and fifteen healthy controls.

RESULTS

Compared with healthy controls, both KS patient groups showed higher levels of apathy as rated by a close informant. We found no difference between both KS patient groups and the healthy control group on the self-report section of the Pleasant Activities List, suggesting that motivation is still intact in KS patients. It is important to note a discrepancy was found between self-reporting and proxy reporting on this list. KS patients with cerebrovascular comorbidity showed more severe emotional blunting compared to both KS patients without cerebrovascular comorbidity and healthy controls. The competency to consent was lower in patients compared with healthy controls, but no difference was found between KS patients with cerebrovascular comorbidity and those without.

CONCLUSIONS

Our results suggest that KS patients show increased levels of general apathy compared with healthy controls. Patients show a diminished competency to consent and increased emotional blunting, while motivation is not compromised. Cerebrovascular comorbidity in KS forms a high risk for emotional blunting. The results of this study suggest that apathy is a severe problem in KS. More attention in both the literature and clinical practice would benefit this complex patient population.

Wet Beriberi Associated with Hikikomori Syndrome

Wet beriberi, characterized by high cardiac output with predominantly right-sided heart failure and lactic acidosis, is a disease caused by thiamine deficiency, and is rarely seen in modern society. However, patients with social withdrawal syndrome, also known as hikikomori syndrome, may be a new population at risk of thiamine deficiency. Hikikomori syndrome, first recognized in Japan, is becoming a worldwide issue. A 39-year-old Japanese patient was brought to our hospital, with a 3-week history of progressive shortness of breath and generalized edema. The patient had right-sided high-output heart failure, lactic acidosis, and Wernicke-Korsakoff syndrome. Because of his history of social isolation, we diagnosed hikikomori syndrome according to the Japanese government's definition, which is as follows: lifestyle centered at home; no interest or willingness to attend school or work; persistence of symptoms beyond 6 months; and exclusion of other psychiatric and developmental disorders. Considering his diagnosis of hikikomori syndrome and social isolation, we suspected malnutrition, particularly thiamine deficiency, and successfully treated him. Clinicians should be aware of the potential risk of thiamine deficiency associated with hikikomori syndrome and initiate thiamine replacement in cases of high-output heart failure associated with lactic acidosis.

[The prevention of Korsakoff's syndrome by offering involuntary care?]

BACKGROUND

The new draft Law on care and coercion focuses on the care of people with a psychogeriatric disorder or intellectual disability. Perhaps this law can be applied to people suffering from chronic alcoholism, associated with an increased risk of Korsakoff's syndrome.

AIM

To explore whether the new draft law on care and coercion can be applied to people suffering from chronic alcoholism who still live at home.

METHOD

A description of possibilities of involuntary homecare to people suffering from chronic alcoholism based on literature, current legislation and two new draft laws.

RESULTS

It seems possible to apply the law care and coercion to people suffering from chronic alcoholism.

CONCLUSION

The application of the draft law care and coercion offers the possibility of providing involuntary homecare to people suffering from chronic alcoholism, enabling the administration of thiamine. This reduces the chances of developing Korsakoff's syndrome. Further research is necessary to explore the practical possibilities in offering involuntary care.

Procedural Learning and Memory Rehabilitation in Korsakoff's Syndrome - a Review of the Literature

Korsakoff's syndrome (KS) is a chronic neuropsychiatric disorder caused by alcohol abuse and thiamine deficiency. Patients with KS show restricted autonomy due to their severe declarative amnesia and executive disorders. Recently, it has been suggested that procedural learning and memory are relatively preserved in KS and can effectively support autonomy in KS. In the present review we describe the available evidence on procedural learning and memory in KS and highlight advances in memory rehabilitation that have been demonstrated to support procedural memory. The specific purpose of this review was to increase insights in the available tools for successful memory rehabilitation and give suggestions how to apply these tools in clinical practice to increase procedural learning in KS. Current evidence suggests that when memory rehabilitation is adjusted to the specific needs of KS patients, this will increase their ability to learn procedures and their typically compromised autonomy gets enhanced.

Healthcare professionals' dilemmas: judging patient's decision making competence in day-to-day care of patients suffering from Korsakoff's syndrome

Patient's decision making competence (PDMC) is a widely discussed subject. Issues of competence, autonomy, well-being and protection of the patient come up every day. In this article we analyse what role PDMC plays in Dutch legislation and what dilemmas healthcare professionals may experience, notably in patients suffering from Korsakoff's syndrome. Dilemmas emerge if professionals want to meet the requirements mentioned in Dutch law and the desires of their patients. The autonomy of the patient and the healthcare professionals' duty to take care of their patient's best interests, create a tension and lead to uncomfortable situations. Healthcare professionals describe difficulty finding a balance between these issues and assessing the degree of mental competence still present. In long term care situations, quality of the relationship between healthcare professionals and their patients seems to be of much more importance in decision making on minor issues of competence than simply relying on legal or house rules. In being committed to their cases, professionals will be more sensitive to individuals habits, abilities, welfare and dignity, which will make it easier to decide on issues of competence, and to find creative solutions to their dilemmas.

Spatial and nonspatial implicit motor learning in Korsakoff's amnesia: evidence for selective deficits

Patients with amnesia have deficits in declarative memory but intact memory for motor and perceptual skills, which suggests that explicit memory and implicit memory are distinct. However, the evidence that implicit motor learning is intact in amnesic patients is contradictory. This study investigated implicit sequence learning in amnesic patients with Korsakoff's syndrome (N = 20) and matched controls (N = 14), using the classical Serial Reaction Time Task and a newly developed Pattern Learning Task in which the planning and execution of the responses are more spatially demanding. Results showed that implicit motor learning occurred in both groups of participants; however, on the Pattern Learning Task, the percentage of errors did not increase in the Korsakoff group in the random test phase, which is indicative of less implicit learning. Thus, our findings show that the performance of patients with Korsakoff's syndrome is compromised on an implicit learning task with a strong spatial response component.

Reversible alcohol-related dementia: a five-year follow-up study using FDG-PET and neuropsychological tests

OBJECTIVE

As the pathophysiology of alcohol-related dementia (ARD) is unclear, we examined a patient with reversible ARD using neuropsychological tests and (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET).

DESIGN

A five-year follow-up case study with neuropsychological tests and FDG-PET.

SETTING

Kyoto University Hospital. Patients A 42-year-old patient who was unable to perform his office duties because of slowly progressive amnesia with executive dysfunction.

RESULTS

The initial evaluation with neuropsychological tests showed severe verbal memory disturbance. The patient did not discuss his excessive alcohol consumption in the initial history-taking session and thiamine deficiency was absent; therefore, early-stage Alzheimer's disease was suspected. Later, the patient revealed prior excessive alcohol intake and his cognitive function improved markedly after a period of abstinence. Retrospective analysis of initial FDG-PET images using a voxel-wise statistical method revealed glucose hypometabolism in the diencephalon and basal forebrain. Follow-up for 5 years after the initial evaluation showed improved cognitive function and recovery of glucose metabolism in the two brain regions.

CONCLUSION

Hypofunction in the diencephalon and basal forebrain was associated with cognitive decline in our patient. This case may provide evidence for the etiopathic brain regions in reversible type ARD.

Neuroimaging of the Wernicke-Korsakoff syndrome

AIM

Presented is the neuroradiological signature of acute Wernicke's encephalopathy (WE), derived from different types of magnetic resonance imaging (MRI) sequences. WE results from thiamine depletion, and its most typical antecedent is chronic alcohol dependence. Brain regions observed with in vivo MRI affected in acute WE include the mammillary bodies, periaqueductal and periventricular gray matter, collicular bodies and thalamus. These affected areas are usually edematous and are best visualized and quantified with MRI sequences that highlight such tissue. Following the acute WE phase and resolution of edema and inflammation of affected brain tissue, WE, if not adequately treated with thiamine repletion, can herald Korsakoff's syndrome (KS), with its symptomatic hallmark of global amnesia, that is, the inability to commit newly encountered (episodic) information to memory for later recall or recognition.

METHODS

Neuropathology of KS detectable with MRI has a different neuroradiological signature from the acute stage and can be observed as tissue shrinkage or atrophy of selective brain structures, including the mammillary bodies and thalamus and ventricular expansion, probably indicative of atrophy of surrounding gray matter nuclei. Quantification of these and additional gray matter structures known to underlie global amnesia reveal substantial bilateral volume deficits in the hippocampus, in addition to the mammillary bodies and thalamus, and modest deficits in the medial septum/diagonal band of Broca. The infratentorium is also affected, exhibiting volume deficits in cerebellar hemispheres, anterior superior vermis and pons, contributing to ataxia of gait and stance.

RESULTS

Consideration of WKS structural brain changes in the context of the neuropathology of non-WKS alcoholism revealed a graded pattern of volume deficits, from mild in non-WKS alcoholics to moderate or severe in WKS, in the mammillary bodies, hippocampus, thalamus, cerebellum and pons. The development and resolution of brain structures affected in acute, chronic and treated WE was verified in longitudinal MRI study of rats that modeled of the interaction of extensive alcohol consumption and thiamine depletion and repletion.

CONCLUSIONS

Thus, neuroradiological examination with MRI is valuable in the diagnosis of acute WE and enables in vivo tracking of the progression of the brain pathology of WE from the acute pathological phase to resolution with thiamine treatment or to progression to KS without treatment. Further, in vivo MRI facilitates translational studies to model antecedent conditions contributing to the development, sequelae and treatment of WE.

Increasing hippocampal acetylcholine levels enhance behavioral performance in an animal model of diencephalic amnesia

Pyrithiamine-induced thiamine deficiency (PTD) was used to produce a rodent model of Wernicke-Korsakoff syndrome that results in acute neurological disturbances, thalamic lesions, and learning and memory impairments. There is also cholinergic septohippocampal dysfunction in the PTD model. Systemic (Experiment 1) and intrahippocampal (Experiment 2) injections of the acetylcholinesterase inhibitor physostigmine were administered to determine if increasing acetylcholine levels would eliminate the behavioral impairment produced by PTD. Prior to spontaneous alternation testing, rats received injections of either physostigmine (systemic=0.075 mg/kg; intrahippocampal=20, 40 ng/muL) or saline. In Experiment 2, intrahippocampal injections of physostigmine significantly enhanced alternation rates in the PTD-treated rats. In addition, although intrahippocampal infusions of 40 ng of physostigmine increased the available amount of ACh in both pair-fed (PF) and PTD rats, it did so to a greater extent in PF rats. The increase in ACh levels induced by the direct hippocampal application of physostigmine in the PTD model likely increased activation of the extended limbic system, which was dysfunctional, and therefore led to recovery of function on the spontaneous alternation task. In contrast, the lack of behavioral improvement by intrahippocampal physostigmine infusion in the PF rats, despite a greater rise in hippocampal ACh levels, supports the theory that there is an optimal range of cholinergic tone for optimal behavioral and hippocampal function.

Memory and the Korsakoff syndrome: not remembering what is remembered

Following the distinction between involuntary unconscious memory, involuntary conscious memory, and intentional retrieval, the focus of the present paper is whether there is an impairment of involuntary conscious memory among Korsakoff patients. At study, participants generated associations versus counted the number of letters with enclosed spaces or the number of vowels in the target words (semantic versus perceptual processing). In the Direct tests, stems were to be used to retrieve the targets with either guessing or no guessing allowed; in the Opposition tests, the stems were to be completed with the first word that came to mind but using another word if that first word was a target word; and in the Indirect tests, no reference was made to the target words from the study phase. In the Direct tests, the performance of Korsakoff patients was not necessarily worse than the one of healthy controls, provided guessing was allowed. More critical for the Korsakoff patients was the deficient involuntary conscious memory. The deficiency explained the suppression failures in the Opposition tests, the absence of performance differences between the Indirect and Opposition tests, the absence of a beneficial effect in providing information about the status of the stem, the performance boost when allowed to guess, and the very low rate of "Know"/"Remember" responses.

Interaction between emotion and memory: importance of mammillary bodies damage in a mouse model of the alcoholic Korsakoff syndrome

Chronic alcohol consumption (CAC) can lead to the Korsakoff syndrome (KS), a memory deficiency attributed to diencephalie damage and/or to medial temporal or cortical related dysfunction. The etiology of KS remains unclear. Most animal models of KS involve thiaminedeficient diets associated with pyrithiamine treatment. Here we present a mouse model of CAC-induced KS. We demonstrate that CAC-generated retrieval memory deficits in working/ episodic memory tasks, together with a reduction of fear reactivity, result from damage to the mammillary bodies (MB). Experimental lesions of MB in non-alcoholic mice produced the same memory and emotional impairments. Drugs having anxiogenic-like properties counteract such impairments produced by CAC or by MB lesions. We suggest (a) that MB are the essential components of a brain network underlying emotional processes, which would be critically important in the retrieval processes involved in working/ episodic memory tasks, and (b) that failure to maintain emotional arousal due to MB damage can be a main factor of CAC-induced memory deficits. Overall, our animal model fits well with general neuropsychological and anatomic impairments observed in KS.

Processing of Emotional Facial Expressions in Korsakoff's Syndrome

Interpersonal contacts depend to a large extent on understanding emotional facial expressions of others. Several neurological conditions may affect proficiency in emotional expression recognition. It has been shown that chronic alcoholics are impaired in labelling emotional expressions. More specifically, they mislabel sad expressions, regarding them as more hostile. Surprisingly, there has been relatively little research on patients with Korsakoff's syndrome as a result of chronic alcohol abuse. The current study investigated 23 patients diagnosed with Korsakoff's syndrome compared to 23 matched control participants. This study is the first to make use of a newly developed sensitive paradigm to measure emotion recognition for several emotions (anger, disgust, fear, happiness, sadness and surprise). The results show that patients with Korsakoff's syndrome are impaired at recognizing angry, fearful and surprised facial emotional expressions. These deficits might be due to the reported sub-cortical brain dysfunction in Korsakoff's syndrome.

Aphasic and amnesic patients' verbal vs. nonverbal retentive abilities

Four different groups of patients (aphasics, alcoholic Korsakoffs, chronic alcoholics, and control patients) were asked to detect either repeated words presented orally, repeated words presented visually, repeated pictures or repeated shapes, during the presentation of a list of similarly constructed stimuli. It was discovered that on the verbal tasks, the number of words intervening between repetitions had more effect on the aphasics than on the other groups of patients. However, for the nonverbal picture repetition and shape repetition tasks, the aphasics' performance was normal, while the alcoholic Korsakoff patients were most affected by the number of intervening items. It was concluded that the aphasics' memory deficit demonstrated by the use of this paradigm was specific to the presentation of verbal material.

Functional MRI study of diencephalic amnesia in Wernicke–Korsakoff syndrome

Anterograde amnesia in Wernicke-Korsakoff syndrome is associated with diencephalic lesions, mainly in the anterior thalamic nuclei. Whether diencephalic and temporal lobe amnesias are distinct entities is still not clear. We investigated episodic memory for faces using functional MRI (fMRI) in eight controls and in a 34-year-old man with Wernicke-Korsakoff syndrome and diencephalic lesions but without medial temporal lobe (MTL) involvement at MRI. fMRI was performed with a 1.5 tesla unit. Three dual-choice tasks were employed: (i) face encoding (18 faces were randomly presented three times and subjects were asked to memorize the faces); (ii) face perception (subjects indicated which of two faces matched a third face); and (iii) face recognition (subjects indicated which of two faces belonged to the group they had been asked to memorize during encoding). All activation was greater in the right hemisphere. In controls both the encoding and recognition tasks activated two hippocampal regions (anterior and posterior). The anterior hippocampal region was more activated during recognition. Activation in the prefrontal cortex was greater during recognition. In the subject with Wernicke-Korsakoff syndrome, fMRI did not show hippocampal activation during either encoding or recognition. During recognition, although behavioural data showed defective retrieval, the prefrontal regions were activated as in controls, except for the ventrolateral prefrontal cortex. fMRI activation of the visual cortices and the behavioural score on the perception task indicated that the subject with Wernicke-Korsakoff syndrome perceived the faces, paid attention to the task and demonstrated accurate judgement. In the subject with Wernicke-Korsakoff syndrome, although the anatomical damage does not involve the MTL, the hippocampal memory encoding has been lost, possibly as a consequence of the hippocampal-anterior thalamic axis involvement. Anterograde amnesia could therefore be the expression of damage to an extended hippocampal system, and the distinction between temporal lobe and diencephalic amnesia has limited value. In the subject with Wernicke-Korsakoff syndrome, the preserved dorsolateral prefrontal cortex activation during incorrect recognition suggests that this region is more involved in either the orientation or attention at retrieval than in retrieval. The lack of activation of the prefrontal ventrolateral cortex confirms the role of this area in episodic memory formation.

[Neurocognition of psychiatric patients]

Cognitive, mnestic, and emotional disturbances can occur in a wide range of psychiatric patients. Both neurochemical alterations as well as structural brain abnormalities can be neural correlates of neuropsychological dysfunctions in these patients. In this paper, we give an introduction to neuropsychological domains with a focus on different kinds of memory and executive functions. Thereafter, we describe neurocognitive deteriorations in patients with schizophrenia, depression, alcohol addiction, and Korsakoff's syndrome. Brain alterations affect primarily parts of the frontal lobe, especially the dorsolateral prefrontal and the orbitofrontal cortex. This can be seen in volume reduction, glucose hypometabolism, or dysfunctions of dopaminergic fronto-striatal loops. Furthermore, structural or functional changes of hippocampal formation, anterior cingulate gyrus, amygdala, and different thalamic nuclei are also involved in neurocognitive disturbances of psychiatric patients.

Procedural memory in Korsakoff's disease under different movement feedback conditions

Within the field of cognitive neuroscience, it has become widely accepted to distinguish between declarative and nondeclarative memory, with different neurobiological substrates subserving these memory structures. This distinction has been inferred from the study of amnesic patients, including those suffering from Korsakoff's syndrome. It is commonly agreed that Korsakoff patients demonstrate intact memory for motor and perceptual skills (nondeclarative) whereas memory of various forms of factual knowledge (declarative) is severely impaired. In the present study, Korsakoff patients and a group of age-matched controls learned a new bimanual motor skill whereby performance was assessed in the presence and absence of augmented visual information feedback. Findings demonstrated that Korsakoff patients were able to learn and retain this skill when directive augmented information feedback was provided while no learning occurred at all in the absence of this information. These observations shed new light on the conditions required for preserved memory in amnesic patients and challenge the classic view that nondeclarative memory is invariably preserved. Instead, the quality of memory across both motor and cognitive dimensions appears to depend on the availability of task-specific information to guide performance, presumably allowing amnesic patients to bypass affected brain areas. This prompts for a reevaluation of current notions about procedural memory capacity in Korsakoff patients.

Complicações psiquiátricas do uso crônico do álcool: síndrome de abstinência e outras doenças psiquiátricas

A síndrome de abstinência alcoólica é um quadro agudo, caracterizado por um conjunto de sinais e sintomas autolimitados, com gravidade variada, secundário à interrupção total ou parcial do consumo de álcool, podendo ser associado a inúmeros problemas clínicos e/ou outros transtornos psiquiátricos. O objetivo deste artigo é rever as principais complicações psiquiátricas secundárias à síndrome de abstinência alcoólica, como convulsões e delirium tremens, bem como algumas outras condições psiquiátricas associadas à dependência de álcool, como as síndromes de Wernicke Korsakoff e de Marchiava Bignami. Pretende-se, com isso, auxiliar no diagnóstico precoce e tratamento adequado, minimizando assim a morbidade e a mortalidade associadas a tais complicações.

Frontal lobe dysfunctions in Korsakoff's syndrome and chronic alcoholism: continuity or discontinuity?

The effect of long-term heavy alcohol consumption on brain functions is still under debate. The authors investigated a sample of 17 Korsakoff amnesics, 23 alcoholics without Korsakoff's syndrome, and 21 controls with peripheral nerve diseases, matched for intelligence and education. Executive functions were examined for word fluency, the modified Wisconsin Card Sorting Test, an alternate response task, and an "n-back" working memory task. Korsakoff amnesics, but not alcoholics, showed a marked memory impairment. They also scored lower in each of the executive tasks-the alcoholics only in the alternate response task. This task also correlated with the years of the alcohol dependency. First, the authors conclude that Korsakoff's syndrome is associated not only with a memory impairment but also with a global executive deficit. Second, the decline in the ability to alternate between different responses argues for a restricted neurotoxic effect of alcohol on some frontal lobe areas.

Impaired processing of affective prosody in Korsakoff's syndrome

In order to further characterize reported deficits in affect perception in alcoholic Korsakoff patients, selected prosody subtests from the Tübingen Affect Battery were administered to seven Korsakoff patients and seven normal control participants. Results indicated that both linguistic and affective prosody discrimination were intact in Korsakoff patients. As well, affective prosody identification was unimpaired when the semantic content of the sentence was emotionally congruent with affective prosody. In contrast, affective prosody identification was significantly impaired when the semantic content was either neutral or incongruent with prosody. These results suggest that Korsakoff patients are impaired in interpreting the meaning of affective prosody in the absence of semantic cues as to the emotional content of sentences.

Is implicit learning spared in amnesia? Rule abstraction and item familiarity in artificial grammar learning

We examined implicit learning of an artificial grammar in amnesic and control participants. The "biconditional" grammar used to generate study and test strings allows two potential sources of judgements in artificial grammar learning to be unconfounded: participants could either learn the abstract biconditional rules or could learn about the distributional statistics of the surface elements (e.g. bigrams) composing the study items. Test strings varied these two sources orthogonally. We found no evidence of abstract rule learning either in the control or amnesic groups. In contrast, both groups learned about the surface elements and tended to call test strings "grammatical" when they were composed of familiar bigrams. However, this sensitivity to bigram familiarity was significantly reduced in the amnesic compared to the control group. The results challenge the claim that implicit learning is intact in amnesia.

The National Adult Reading Test as a measure of premorbid intelligence: a comparison with estimates derived from demographic variables

Since its publication in 1982, the National Adult Reading Test (NART; Revised Version, NART-R) has become a widely accepted method for estimating premorbid levels of intelligence in neuropsychological research. However, the assumption that NART/NART-R performance is relatively independent of brain damage has been increasingly challenged in recent years. In a number of conditions, including Alzheimer dementia and Korsakoff's syndrome, studies have indicated a deterioration in reading ability, leading to an underestimated premorbid IQ. In a reaction to these studies, some researchers have advocated the use of demographic variables as a more suitable foundation for accurately predicting premorbid intelligence. We addressed this issue by calculating IQ estimates on the basis of NART/NART-R, demographic variables, and a combination of the two approaches and by comparing these with current WAIS/WAIS-R IQ in patients with Korsakoff's syndrome, Alzheimer dementia, frontal or temporal lobe lesions, and in healthy controls. Estimated premorbid IQs did not differ across groups, whether derived from NART/NART-R or demographic variables. Those based on NART/NART-R demonstrated higher correlations with current WAIS/WAIS-R IQ in controls and patients than those derived from demographic variables. An equation combining NART scores with demographic variables did not significantly increase the amount of variance in IQ explained by NART only, either in patients or controls. The data offer reassurance regarding the continued use of NART as a valid estimate of premorbid intelligence in a number of conditions.

An atypical neuropsychological profile of a Korsakoff syndrome patient throughout the follow-up

The basis of amnesia in alcoholic Wernicke-Korsakoff syndrome (WKS) has been generally associated with diencephalic lesions and more specifically with lesions of the anterior thalamic nuclei. These brain structures are considered to be involved in encoding/consolidation processes of episodic memory. However, frontal lobe damage responsible for executive function deficits has also been documented. The present report details the nature and extent of amnesia in an alcoholic patients with WKS and which appears to be mainly due to frontal lobe (executive) deficits.

Therapeutic effects of an acetylcholinesterase inhibitor (donepezil) on memory in Wernicke-Korsakoff's disease

Wernicke-Korsakoff's disease (WKD) is cognitively an amnestic state resulting from strategic lesions in the limbic system subserving the episodic memory network and resulting from thiamine deficiency. Neurochemical deficits have been implicated in the pathophysiology of amnesia based on the pathologic observations that various brainstem and basal forebrain nuclei are also affected. Previous treatment attempts with serotoninergic, noradrenergic, and cholinergic drugs have given controversial results. The objective of this study was to assess the effects of a cholinesterase inhibitor, donepezil, on memory, attention, and executive functions in patients with nonalcoholic WKD. Seven patients who developed WKD after a hunger strike were included in this single, blind, placebo-controlled, one-way, crossover study. The patients were administered donepezil during the first 30 days, and were administered placebo during the following 30 days. Neuropsychological tests to evaluate verbal and visual memory, and attention and executive function were performed on days 0, 31, and 61. All patients completed both phases of the study. There were no statistically significant differences between the three evaluations, except for a difference between active treatment and the placebo phase during recall of the Rey-Osterrieth complex figure, which was in favor of the placebo phase. There were no significant changes in favor of the active treatment. Cholinergic treatment with the cholinesterase inhibitor donepezil does not seem to provide marked beneficial effects in patients with WKD in this small, descriptive study. This may be because pathways mediating channel and state-dependent functions are impaired in this disease, and enhancement of state-dependent cholinergic transmission may not be sufficient. Subtle benefits, however, cannot be excluded because of the small sample size and the relatively short duration of the treatment.

The role of explicit memory processes in cross-modal priming: an investigation of stem completion priming in amnesia

To clarify the role of explicit memory processes in cross-modal priming, two experiments examined the status of cross-modal stem completion priming in amnesia. Experiment 1 used a standard behavioral paradigm in which stems corresponding to studied and unstudied words were intermixed. Amnesic patients showed intact within- and cross-modal priming, but, in contrast to controls, they recognized very few of their completions as having been on the study list. This finding suggests that memorial awareness is not necessary for cross-modal priming to occur. Experiment 2 used a paradigm modeled after functional imaging studies, in which stems corresponding to studied and unstudied words were blocked. Amnesic patients showed intact within-modal priming, but impaired cross-modal priming. This finding is consistent with the notion that a blocked format induces voluntary retrieval strategies in normal participants.

Structural MRI volumetric analysis in patients with organic amnesia, 1: methods and comparative findings across diagnostic groups

BACKGROUND

If they are to be replicable, MRI volume measurements require explicit definitions of structures and of criteria for delineating these structures on MRI. Previously published volumes in healthy subjects show considerable differences in measurements across different studies, including a fourfold variation in estimates of hippocampal volume. Previous neuroimaging reports in patients with Korsakoff syndrome have generally found widespread or non-specific change, whereas in patients with herpes encephalitis the extent of pathological involvement reported beyond the temporal lobes has varied.

METHOD

In the present study, a clear set of anatomical criteria and detailed MRI segmentation procedures were applied to measure whole brain, frontal and temporal lobe, and anterolateral and medial temporal volumes, as well as thalamic areas in patients with organic amnesia (from Korsakoff's syndrome, herpes encephalitis, and focal frontal lesions) as well as healthy controls.

RESULTS

Patients with Korsakoff's syndrome showed decreased thalamic measurements but no significant changes in the medial temporal lobes, whereas patients with herpes encephalitis showed severe medial temporal but not thalamic atrophy. In the patients with known frontal lobe lesions, quantitative analysis on MRI showed reduced frontal lobe volume but no significant temporal lobe or thalamic atrophy.

CONCLUSION

Quantified MRI can be a useful technique with which to examine brain-cognitive relations, provided that detailed techniques are explicitly described. In particular, specific patterns of volume change can be found in vivo in patients with Korsakoff's syndrome and those with herpes encephalitis.

Does the medial temporal lobe bind phonological memories?

The medial temporal lobes play a central role in the consolidation of new memories. Medial temporal lesions impair episodic learning in amnesia, and disrupt vocabulary acquisition. To investigate the role of consolidation processes in phonological memory and to understand where and how, in amnesia, these processes begin to fail, we reexamined phonological memory in the amnesic patient HM. While HM's word span performance was normal, his supraspan recall was shown to be markedly impaired, with his recall characterized by a distinctive pattern of phonological errors, where he recombined phonemes from the original list to form new response words. These were similar to errors observed earlier for patients with specifically semantic deficits. Amnesic Korsakoff's patients showed a similar, though much less marked, pattern. We interpret the data in terms of a model of lexical representation where temporal lobe damage disrupts the processes that normally bind semantic and phonological representations.

Differential outcomes training facilitates memory in people with Korsakoff and Prader-Willi syndromes

This article presents evidence that a teaching procedure called differential outcomes training enhances learning and memory. Differential outcomes training reinforces correct responses with outcomes that are unique and specific to the stimuli that are to be remembered. Teaching with this method enhances performance in people with Korsakoff syndrome and people with Prader-Willi syndrome, populations known to have learning and working memory deficits. This initial evidence that persons with learning and memory deficits benefit from differential outcomes training should encourage future work on the development of an intervention using this type of training to aide daily functioning by people with learning and memory impairments.

Recognition memory in amnesia: effects of relaxing response criteria

In two experiments, using the remember/know paradigm, we examined whether recognition memory in amnesic patients can be improved by instructing patients to relax their response criterion. Experiment 1 was modeled after a study by Dorfman, Kihlstrom, Cork, and Misiaszek (1995), in which direct instructions to respond more leniently led to an increase in recognition accuracy in patients with ECT-induced amnesia. We failed to extend this finding to patients with global amnesia, but the manipulation was unsuccessful in control subjects as well. In Experiment 2, response criterion was manipulated indirectly by providing information about the alleged base rate of study items on the recognition test. This manipulation led to a criterion shift in control subjects and enhanced discriminability in amnesic patients. Analysis of "remember" and "know" responses suggests that improved accuracy in amnesia was associated with enhanced familiarity-based recognition.

Word frequency and word stem completion in Korsakoff patients

Korsakoff patients are generally agreed to be impaired in conscious recollection, but whether their implicit memory performance is also affected is less certain. A deficit in novelty dependent encoding (i.e., elaboration learning) could account for both types of impairments and predicts a reduced implicit word frequency effect in the patients. This effect was examined with word stem completion in nineteen Korsakoff patients and nineteen healthy controls. The word frequency effect was larger in controls than in patients in absolute terms, but not reliably so. It is concluded that elaboration learning may be spared to some degree in Korsakoff amnesia, but, in line with the original reasoning by Korsakoff (1889/1996), it may only be engaged by the patients when they are continuously prompted to do so.

Prospective remembering of Korsakoffs and alcoholics as a function of the prospective-memory and on-going tasks

Prospective memory is assumed to rely more on the frontal lobes than retrospective memory. Since Korsakoff patients are known to suffer from a general cerebral atrophy and a frontal lobe atrophy in particular, they are expected to show considerably impaired prospective memory. In Experiment 1, the performance of Korsakoff patients on a semantic prospective-memory task (which was embedded in a perceptual on-going task) was particularly bad in Session 1; in Session 2, the Korsakoff patients improved substantially, to reach the performance level of nonamnesic alcoholics. In Experiment 2, prospective memory of the Korsakoff patients and nonamnesic alcoholics was better when the on-going task was more similar to the prospective-memory task; particularly striking was the much better prospective memory in the semantic prospective-memory task when the on-going task requires a semantic analysis than when the on-going task requires perceptual processing. The findings are in agreement with a task-appropriate processing explanation but also in partial agreement with the attention hypothesis of the instance theory of automaticity. Contrary to the frontal lobe hypothesis, prospective memory of the Korsakoff patients was surprisingly good in several aspects of the two experiments.

Cerebellar volume decline in normal aging, alcoholism, and Korsakoff's syndrome: relation to ataxia

The authors used magnetic resonance imaging to measure gray and white matter volumes in cerebellar hemispheres and 4 vermian regions in 61 normal control (NC) men aged 23-72 years, 25 men with uncomplicated alcoholism (ALC), and 8 men and 1 woman with alcoholic Korsakoff s syndrome (KS). NC and ALC took quantitative gait and balance tests. Gray but not white matter volume declined with normal age in both hemispheres and anterior-superior vermis. ALC had gray but not white matter cerebellar hemisphere volume deficits, whereas KS had deficits in both tissue types. ALC and KS had gray and white matter volume deficits in anterior superior but not posterior inferior vermis. ALC had a 1 SD ataxia deficit, significantly and selectively correlated with white matter volume in anterior superior vermis. Regional distribution but not severity of cerebellar volume deficits is similar in alcoholic individuals whether or not complicated by KS and relates to ataxia.

Time estimation by patients with frontal lesions and by Korsakoff amnesics

We studied time estimation in patients with frontal damage (F) and alcoholic Korsakoff (K) patients in order to differentiate between the contributions of working memory and episodic memory to temporal cognition. In Experiment 1, F and K patients estimated time intervals between 10 and 120 s less accurately than matched normal and alcoholic control subjects. F patients were less accurate than K patients at short (< 1 min) time intervals whereas K patients increasingly underestimated durations as intervals grew longer. F patients overestimated short intervals in inverse proportion to their performance on the Wisconsin Card Sorting Test. As intervals grew longer, overestimation yielded to underestimation for F patients. Experiment 2 involved time estimation while counting at a subjective 1/s rate. F patients' subjective tempo, though relatively rapid, did not fully explain their overestimation of short intervals. In Experiment 3, participants produced predetermined time intervals by depressing a mouse key. K patients underproduced longer intervals. F patients produced comparably to normal participants, but were extremely variable. Findings suggest that both working memory and episodic memory play an individual role in temporal cognition. Turnover within a short-term working memory buffer provides a metric for temporal decisions. The depleted working memory that typically attends frontal dysfunction may result in quicker turnover, and this may inflate subjective duration. On the other hand, temporal estimation beyond 30 s requires episodic remembering, and this puts K patients at a disadvantage.

Wernicke-Korsakoff syndrome and the use of brain imaging

The proportion of patients with Korsakoff psychosis (KP) who have a history of Wernicke's encephalopathy is smaller in recent studies compared to previous studies. Neuropsychological tests, magnetic resonance imaging (MRI), and single photon emission computed tomography were conducted in eight patients with KP, only four of whom had had a documented Wernicke episode. All subjects showed amnesia without intellectual deterioration. MRI abnormalities were seen in each group to the same extent (atrophy of mammillary bodies, to a less extent thalamus and some generalized gyral atrophy). No MRI measure differentiated the groups. Cerebral blood flow showed reduction of flow to the anterior temporal regions bilaterally, extending to the parietal lobes, to the same degree in each group. Despite the small number of patients examined, the study supports the belief that patients with an insidious onset of KP have the same pathology as those with classical Wernicke-Korsakoff syndrome. This raises the question of whether episodes of alcohol withdrawal without adequate thiamine protection result in occasionally subclinical Wernicke's events, followed by a subsequently diagnosable KP.

Role of perceptual and organizational factors in amnesics' recall of the Rey-Osterrieth complex figure: a comparison of three amnesic groups

To examine the contribution of visual-perceptual and visual-organizational factors to visual memory in amnesia, Korsakoff, medial temporal, and anterior communicating artery (ACoA) aneurysm amnesics' copy, organization, and recall performance on the Rey-Osterrieth Complex Figure was assessed. Korsakoff patients were matched to medial temporal patients in terms of severity of amnesia, while the ACoA group, which was less severely amnesic, was matched to the Korsakoff patients on performance on executive tasks. Results indicated that while both the ACoA and Korsakoff groups had poorer copy accuracy and organization than controls, only the Korsakoff patients' copy accuracy was worse than the other two amnesic groups. While the Korsakoff patient's visuoperceptual deficits could partially explain this group's poor performance at immediate recall, the Korsakoff group's comparatively worse performance at delayed recall could not be accounted for by poor copy accuracy, reduced visual organization, or even the combined influence of these two factors.

Three words three shapes: A clinical test of memory

Three Words - Three Shapes was designed as an easy "bedside" test for elderly patients that assesses verbal and nonverbal memory within the same modality. In the present study, it was administered to patients with probable Alzheimer's disease (PRAD), a control group of non-demented older subjects (NC) and a group of patients with Korsakoff's amnesia (KA). Incidental recall and several other measures of learning, retention and recognition differentiated control from PRAD and KA subjects. PRAD and KA subjects' performance was similar, but there were some material-specific interactions. This test is relatively easy and some of the derived measures could prove useful in staging amnesia progression beyond the earliest stages of PRAD when more difficult tests yield floor effects.

Normal cognitive performance in patients with chronic alcoholism in contrast to patients with Korsakoff's syndrome

This study investigated which cognitive deficits are associated with chronic alcoholism. Neuropsychological profiles and MRI brain structure volumes of 14 patients with Korsakoff's syndrome, 15 patients with chronic alcoholism, and 16 healthy control subjects were compared. The patients with alcoholism had a normal cognitive performance and normal brain structure volumes. The patients with Korsakoff's syndrome had performance deficits on tests of memory, visuoperceptual, and executive functions, as well as reduced brain structure volumes. The results suggest that the cognitive deficits cannot be ascribed to mere chronic consumption of alcohol. If cognitive deficits are present in patients with chronic alcoholism, this may point to an underlying brain disorder.

Memory for object locations in Korsakoff's amnesia

Deficits in spatial context memory are an important characteristic of Korsakoff's amnesia. In memory for spatial context information, there is evidence for a functional dissociation of three separate processes: (1) binding of object information to locations (i.e. binding complex memories), (2) exact, metric processing of Euclidean co-ordinates, and (3) an integration mechanism. In the present study, these sub-mechanisms were assessed experimentally in a group of Korsakoff patients (N = 20) and compared to healthy controls (N = 20) to see whether selective deficits can be demonstrated. It was found that Korsakoff patients display deficits on all three spatial-memory conditions, which are not the primary result of deficits in visuo-spatial construction and memory for object identity. No evidence for selective impairments could be observed. These impairments can be linked to damage of diencephalic regions and perhaps the parietal cortex.

Degeneration of anterior thalamic nuclei differentiates alcoholics with amnesia

The specific neural substrate underlying the amnesia in alcoholic Korsakoff's psychosis is poorly defined because of the considerable brain damage found in many non-amnesic alcoholics, particularly those with Wernicke's encephalopathy. Using operational criteria to identify alcoholics with and without Korsakoff's psychosis, we have shown that many of the cortical and subcortical regions involved in the encoding and retrieval of episodic memory are either unaffected (hippocampus) or damaged to the same extent (prefrontal cortex and the cholinergic basal forebrain) in both amnesic and non-amnesic alcoholics. In the present study we analysed the diencephalic regions involved in episodic memory to determine the neural substrate for the amnesia observed in alcoholic Korsakoff's psychosis. The number of neurons in spaced serial sections containing the hypothalamic mamillary nuclei and the anterior and mediodorsal thalamic nuclei was estimated using unbiased stereological techniques. Neurodegeneration of the hypothalamic mamillary nuclei and the mediodorsal thalamic nuclei was substantial in both non-amnesic and amnesic alcoholics with Wernicke's encephalopathy. However, neuronal loss in the anterior thalamic nuclei was found consistently only in alcoholic Korsakoff's psychosis. This is the first demonstration of a differentiating lesion in alcoholic Korsakoff's psychosis and supports previous evidence that degeneration of thalamic relays are important in this memory disorder.

A comparison of egocentric and allocentric spatial memory in medial temporal lobe and Korsakoff amnesics

Two patients with medial temporal lobe damage, seven Korsakoff amnesics and fourteen healthy control subjects were tested on three conditions of a spatial memory test ('short delay', 'allocentric' and 'egocentric'). The task required subjects to recall the position of a single spot of light presented on a board after various delays. The 'short delay' condition tested memory over very short, unfilled intervals. The other two conditions used longer, filled delays. The allocentric condition required subjects to move to a different place around the board before recalling the position of the light. In the egocentric condition stimuli were presented in darkness, which eliminated allocentric cues. The Korsakoff amnesics were impaired at all delays of the short delay tasks, suggesting poor encoding. On the allocentric and egocentric tasks the Korsakoff amnesics showed a comparable impairment in the two conditions, which worsened with delay. This accelerated forgetting suggested that the Korsakoff amnesics also had impaired memory for allocentric and egocentric information. The patients with medial temporal lobe damage were unimpaired in the 'short delay' condition suggesting intact encoding and short-term memory of spatial information. However, they were impaired in the allocentric condition and showed accelerated loss of allocentric spatial information. In the egocentric condition, while the performance of one patient was impaired, the performance of the other was as good as controls. This result suggests that, in contrast to allocentric spatial memory, which is sensitive to medial temporal lobe damage, an intact medial temporal lobe need not be necessary for successful performance on an egocentric spatial memory task.