Various degrees of dementia in a selected group of gastrectomized patients with low serum B12.

Forty-two gastrectomized patients (mean age 56 years) with a serum B12 level less than 200 pg/ml were studied by psychological testing and electroencephalography. A total of 50 per cent exhibited mild to moderate or more severe intellectual impairment, judging by the history and psychological testing. EEG abnormalities were found, mainly in the form of reduced dominant activity, in 48 per cent. The results of psychological testing were in accurate conformity with the findings of dementia due to other reasons. The characteristic findings were depression and lability of affect, with a high frequency of suicidal attempts (20 per cent). We interpret the cerebral abnormalities as a result of vitamin B12 deficiency.