According to the drug information reported by the National Institutes of Health (NIH), Olanzapine (brand name: Zyprexa), memory loss is not considered one of the common side effects of this medication.  This is not to say that memory loss does not occur in some individuals taking this drug since other factors even unrelated to the medication may be contributing to the memory loss. You also need to consider other factors such as full medical diagnosis, medical and health history, possible interaction with other medications, and other side effects that may contribute to memory loss, such as confusion and depression.  Olanzapine is in a class of medications called atypical antipsychotics, which are typically used to treat symptoms of schizophrenia, although these drugs have also been prescribed ‘off label' to treat some behavioral issues associated with dementia.  There is a lot of controversy surrounding the prescribing of these types of drugs in the dementia population so it is very important to speak with the prescribing physician to best understand all possible risks and benefits.