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What is Korsakoff's psychosis is diagnosed by - and explain in detail?
Memory impairment in korsakoff's syndrome

Antegrade amnesia → New learning impaired.
Retrograde amnesia → (Loss of memory of past events)
Impaired recent memory
Relatively preserved remote memory
Impairment of explicit (conscious or declarative) type of long-term memory
Relatively preserved implicit (unconscious or non-declarative) type of long-term memory

Don’t get confuse remote memory with long-term memory. All remote memories are long-term memories. However, not all
long-term memories are remote memories. Read below:-

Recent memory includes both short-term (immediate) and long-term (delayed) memory. In Korsakoff's syndrome, recent memory is impaired, that means both short term and long term memories are involved. However, only long-term memory of recent past involved (say, for example, 20-30 minutes or 1 hour).
Remote memory is long-term memory of more distant past, which is not impaired in Korsakoff's syndrome. Therefore, long-term memory of the distant past (say for example, before the onset of illness) is not impaired.