Reconstructing cognition in Korsakoff’s syndrome: Diagnosis, residual capacities, and rehabilitation

Abstract

Korsakoff's syndrome (KS) is a preventable neuropsychiatric disorder caused by alcoholism induced vitamine B1 deficiency. In the acute phase of this vitamine B1 deficiency, called Wernicke’s encephalopathy (WE), the neuropsychiatric disorder is fully reversibly by fast intravenous or intramuscular thiamine treatment. In the chronic phase, KS is characterized by cognitive problems, such as severe memory problems and executive deficiencies. Due to these problems autonomy is vastly restricted and patients are in need of chronic care. In this dissertation, three topics that are fundamental to KS are discussed: 1) The diagnosis of KS in the acute and chronic phase 2) Residual learning potential in KS 3) The rehabilitation of patients with KS Regarding the diagnosis, this dissertation shows that late treatment of patients with acute WE can result in a severe irreversible state of confusion that resembles the acute stage. It is therefore relevant to have a high suspicion of WE in alcoholic patients and preventively treat them with vitamine B1 injections. Although it has been known for over 60 years that this treatment has the potency to improve the neuropsychiatric syndrome in the early stage of WE, this particular treatment is still uncommon medical practice, leading to unnecessary cases of chronic WE or KS. In the chronic phase, neuropsychological assessment is vital to diagnose KS correctly. Cognitive screening instruments can be successfully applied to detect the cognitive problems in KS. The recently developed Montreal Cognitive Assessment is a better cognitive screening instrument to detect KS than the traditionally frequently applied Mini-Mental State Examination. Once diagnosed, patients with KS require specific forms of care that are fundamentally different from regular psychogeriatric dementia care, as reflected by discrepant scores on indices for quality of life. With respect to learning and memory, KS is characterized by severe anterograde amnesia. The memory deficiencies are most pronounced in declarative long-term memory and learning. Spatial declarative long-term memory seems however better preserved than verbal declarative memory on comparable neuropsychological tests. Moreover, some aspects of memory and learning are relatively better preserved in KS than declarative memory. For example, we may automatically take the right turn during spatial navigation or start searching for hidden objects in the right direction without conscious place memory. As this dissertation shows, these forms of implicit spatial learning are relatively spared in KS and are likely to contribute to the residual potential to learn novel routes. When memory rehabilitation is adjusted to the specific needs of KS patients, this will increase their ability to learn and their typically compromised autonomy gets enhanced. One promising form of rehabilitation is Errorless Learning (EL). EL can be successfully applied as a rehabilitation technique to learn and maintain skills or instrumental activities of daily living in patients with KS. The application of such techniques might increase the autonomy of patients and is likely to contribute to a better quality of life. To conclude, as this dissertation suggests it is particularly relevant to use the spared learning potential in KS to rehabilitate patients and reconstruct cognition in KS.