Pseudodementia in a twenty-one-year-old with bipolar disorder and vitamin B12 and folate deficiency.

A twenty-one-year-old female known to suffer from bipolar type I disorder developed features of a pseudodementia. Following prompt initial response to treatment with antidepressants, there was an early recurrence of cognitive impairment. Blood investigations confirmed a macrocytic anaemia and vitamin B12 and folate deficiencies. There was dramatic resolution of cognitive impairment after vitamin replacement. This suggested the occurrence of a reversible nutritional dementia and reinforced the need to rule out secondary organic causes of psychiatric symptoms even in patients previously diagnosed with a primary psychiatric disorder.