Background: Dementia is a chronic, progressive and ultimately fatal neurodegenerative disease. Advanced dementia is characterised by profound cognitive impairment, inability to communicate verbally and complete functional dependence. Usual care of people with advanced dementia is not underpinned universally by a palliative approach. Palliative care has focused traditionally on care of people with cancer, but for more than a decade, there have been calls worldwide to extend palliative care services to include all people with life-limiting illnesses in need of specialist care, including people with dementia. This review is an updated version of a review first published in 2016., Objectives: To assess the effect of palliative care interventions in advanced dementia., Search Methods: We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's Specialised Register on 7 October 2020. ALOIS contains records of clinical trials identified from monthly searches of several major healthcare databases, trial registries and grey literature sources. We ran additional searches across MEDLINE (OvidSP), Embase (OvidSP), four other databases and two trial registries on 7 October 2020 to ensure that the searches were as comprehensive and as up-to-date as possible., Selection Criteria: We searched for randomised (RCTs) and non-randomised controlled trials (nRCTs), controlled before-and-after studies and interrupted time series studies evaluating the impact of palliative care interventions for adults with advanced dementia of any type. Participants could be people with advanced dementia, their family members, clinicians or paid care staff. We included clinical interventions and non-clinical interventions. Comparators were usual care or another palliative care intervention. We did not exclude studies based on outcomes measured., Data Collection and Analysis: At least two review authors (SW, EM, PC) independently assessed all potential studies identified in the search against the review inclusion criteria. Two authors independently extracted data from eligible studies. Where appropriate, we estimated pooled treatment effects in a fixed-effect meta-analysis. We assessed the risk of bias of included studies using the Cochrane Risk of Bias tool and the overall certainty of the evidence for each outcome using GRADE., Main Results: Nine studies (2122 participants) met the review inclusion criteria. Two studies were individually-randomised RCTs, six were cluster-randomised RCTs and one was a controlled before-and-after study. We conducted two separate comparisons: organisation and delivery of care interventions versus usual care (six studies, 1162 participants) and advance care planning interventions versus usual care (three studies, 960 participants). Two studies were carried out in acute hospitals and seven in nursing homes or long-term care facilities. For both comparisons, we found the included studies to be sufficiently similar to conduct meta-analyses. Changes to the organisation and delivery of care for people with advanced dementia may increase comfort in dying (MD 1.49, 95% CI 0.34 to 2.64; 5 studies, 335 participants; very low certainty evidence). However, the evidence is very uncertain and unlikely to be clinically significant. These changes may also increase the likelihood of having a palliative care plan in place (RR 5.84, 95% CI 1.37 to 25.02; 1 study, 99 participants; I 2 = 0%; very low certainty evidence), but again the evidence is very uncertain. Such interventions probably have little effect on the use of non-palliative interventions (RR 1.11, 95% CI 0.71 to 1.72; 2 studies, 292 participants; I 2 = 0%; moderate certainty evidence). They may also have little or no effect on documentation of advance directives (RR 1.46, 95% CI 0.50 to 4.25; 2 studies, 112 participants; I 2 = 52%; very low certainty evidence), or whether discussions take place about advance care planning (RR 1.08, 95% CI 1.00 to 1.18; 1 study, 193 participants; I 2 = 0%; very low certainty evidence) and goals of care (RR 2.36, 95% CI 1.00 to 5.54; 1 study, 13 participants; I 2 = 0%; low certainty evidence). No included studies assessed adverse effects. Advance care planning interventions for people with advanced dementia probably increase the documentation of advance directives (RR 1.23, 95% CI 1.07 to 1.41; 2 studies, 384; moderate certainty evidence) and the number of discussions about goals of care (RR 1.33, 95% CI 1.11 to 1.59; 2 studies, 384 participants; moderate certainty evidence). They may also slightly increase concordance with goals of care (RR 1.39, 95% CI 1.08 to 1.79; 1 study, 63 participants; low certainty evidence). On the other hand, they may have little or no effect on perceived symptom management (MD -1.80, 95% CI -6.49 to 2.89; 1 study, 67 participants; very low certainty evidence) or whether advance care planning discussions occur (RR 1.04, 95% CI 0.87 to 1.24; 1 study, 67 participants; low certainty evidence)., Authors' Conclusions: The evidence on palliative care interventions in advanced dementia is limited in quantity and certainty. When compared to usual care, changes to the organisation and delivery of care for people with advanced dementia may lead to improvements in comfort in dying, but the evidence for this was of very low certainty. Advance care planning interventions, compared to usual care, probably increase the documentation of advance directives and the occurrence of discussions about goals of care, and may also increase concordance with goals of care. We did not detect other effects. The uncertainty in the evidence across all outcomes in both comparisons is mainly driven by imprecision of effect estimates and risk of bias in the included studies., (Copyright © 2021 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.)