What vitamin deficiency usually causes memory lapses? post gastric bypass 9/2011

Vitamins: The most common vitamin deficiencies seen after gastric bypass are with vitamin b12, vitamin d and iron. Some have low calcium. Vitamin B12 deficiency can affect the central nervous system and memory.

B12 deficiency : Vitamin B12 deficiency is probably the most commonly associated with memory loss. Typically it occurs in people whose digestive systems do not adequately absorb the vitamin from the foods they eat. This can be caused by pernicious anemia, atrophic gastritis, crohn's disease, celiac disease, bacterial growth, or a parasite, excessive alcohol consumption.