Korsakoff syndrome (KS) is a disorder of the central nervous system characterized by amnesia, deficits in explicit memory, and confabulation. This neurological disorder is caused by a deficiency of thiamine (vitamin B1) in the brain, and it is typically associated with and exacerbated by the prolonged, excessive ingestion of alcohol. Korsakoff syndrome is often accompanied by Wernicke encephalopathy; this combination is called Wernicke–Korsakoff syndrome. Korsakoff syndrome is named after Sergei Korsakoff, the Russian neuropsychiatrist who described it during the late 19th century. Signs and symptoms There are seven major symptoms of Korsakoff syndrome, an amnestic-confabulatory syndrome: anterograde amnesia, memory loss for events after the onset of the syndrome retrograde amnesia, memory loss extends back for some time before the onset of the syndrome amnesia of fixation, also known as fixation amnesia (loss of immediate memory, a person being unable to remember events of the past few minutes) confabulation, that is, invented memories which are then taken as true, due to gaps in memory, with such gaps sometimes associated with blackouts minimal content in conversation lack of insight apathy – interest in things is quickly lost, and there is an indifference to change Benon R. and LeHuché R. (1920) described the characteristic signs of Korsakoff syndrome with some additional features including: confabulation (false memories), fixation amnesia, paragnosia or false recognition of places, mental excitation, and euphoria. Thiamine is essential for the decarboxylation of pyruvate, and deficiency during this metabolic process is thought to cause damage to the medial thalamus and mammillary bodies of the posterior hypothalamus, as well as generalized cerebral atrophy. These brain regions are all parts of the limbic system, which is heavily involved in emotion and memory. KS involves neuronal loss, that is, damage to neurons; gliosis, which is a result of damage to supporting cells of the central nervous system, and bleeding also occurs in mammillary bodies. Damage to the medial dorsal nucleus or anterior nuclei of the thalamus (limbic-specific nuclei) is also associated with this disorder. Cortical dysfunction may have arisen from thiamine deficiency, alcohol neurotoxicity, and/or structural damage in the diencephalon. Originally, it was thought that a lack of initiative and a flat affect were important characteristics of emotional presentation in those affected. Studies have questioned this, proposing that neither is necessarily a symptom of KS. Research suggesting that people with Korsakoff syndrome are emotionally unimpaired has made this a controversial topic. It can be