This paper explores the use of advance directives in clinical dementia research. The focus is on advance consent to participation of demented patients in non-therapeutic research involving more than minimal risks and/or burdens. First, morally relevant differences between advance directives for treatment and care, and advance directives for dementia research are discussed. Then attention is paid to the philosophical issue of dementia and personal identity, and the implications for the moral authority of research advance directives. Thirdly, a number of practical (...) shortcomings of advance directives for non-therapeutic dementia research are explored and attention is paid to the role of proxies. It is concluded that upon a closer look the initial attractiveness of advance directives for dementia research is lessened, and that it is doubtful whether these instruments can compensate for the lack of subject consent in case of non-therapeutic dementia research involving more than minimal risks and/or burdens for the incompetent demented subject. (shrink)