BackgroundThis paper synthesises research evidence about the effectiveness of services intended to support and sustain people with dementia to live at home, including supporting carers. The review was commissioned to support an inspection regime and identifies the current state of scientific knowledge regarding appropriate and effective services in relation to a set of key outcomes derived from Scottish policy, inspection practice and standards. However, emphases on care at home and reduction in the use of institutional long term care are common to many international policy contexts and welfare regimes.MethodsSystematic searches of relevant electronic bibliographic databases crossing medical, psychological and social scientific literatures (CINAHL, IngentaConnect, Medline, ProQuest, PsychINFO and Web of Science) in November 2012 were followed by structured review and full-text evaluation processes, the latter using methodology-appropriate quality assessment criteria drawing on established protocols.ResultsOf 131 publications evaluated, 56 were assessed to be of ‘high’ quality, 62 of ‘medium’ quality and 13 of ‘low’ quality. Evaluations identified weaknesses in many published accounts of research, including lack of methodological detail and failure to evidence conclusions. Thematic analysis revealed multiple gaps in the evidence base, including in relation to take-up and use of self-directed support by people with dementia, use of rapid response teams and other multidisciplinary approaches, use of technology to support community-dwelling people with dementia, and support for people without access to unpaid or informal support.ConclusionsIn many areas, policy and practice developments are proceeding on a limited evidence base. Key issues affecting substantial numbers of existing studies include: poorly designed and overly narrowly focused studies; variability and uncertainty in outcome measurement; lack of focus on the perspectives of people with dementia and supporters; and failure to understanding the complexities of living with dementia, and of the kinds of multifactorial interventions needed to provide holistic and effective support. Weaknesses in the evidence base present challenges both to practitioners looking for guidance on how best to design and deliver evidence-based services to support people living with dementia in the community and their carers and to those charged with the inspection of services.Electronic supplementary materialThe online version of this article (doi:10.1186/s12877-015-0053-9) contains supplementary material, which is available to authorized users.