15th February 2025

A 64-year-old woman is seen by her GP.

A 64-year-old woman is seen by her GP. Her family report that over the past two years they have noticed that she struggles to remember recent events.

Past medical history is significant for inflammatory bowel disease and chronic alcohol dependence. She has followed a vegan diet for many years.

On examination, she has bilateral lateral gaze palsy.

Which deficiency is the most likely cause for her presentation?

Select the SINGLE most appropriate option from the list below. Select ONE option only.