The present invention generally relates to a method for an improved treatment for Alzheimer's disease (AD) using immunotherapy, e.g., immunotherapy targeting .beta. amyloid (A.beta.), e.g., immunotherapy based on AN1792. In one embodiment, the method allows for predicting an adverse clinical response, and therefore allows for an improved safety profile of AN1792. In another embodiment, the method allows for predicting a favorable clinical response, and therefore allows for an improved efficacy profile of AN1792. The methods of the present invention may be combined to predict a favorable clinical response and the lack of an adverse clinical response.