Abstract: We included five RCTs involving 201 carers assessing the effectiveness of MBSR. Controls used in included studies varied in structure and content. Mindfulness-based stress reduction programmes were compared with either active controls (those matched for time and attention with MBSR, i.e. education, social support, or progressive muscle relaxation), or inactive controls (those not matched for time and attention with MBSR, i.e. self help education or respite care). One trial used both active and inactive comparisons with MBSR. All studies were at high risk of bias in terms of blinding of outcome assessment. Most studies provided no information about selective reporting, incomplete outcome data, or allocation concealment. 1. Compared with active controls, MBSR may reduce depressive symptoms of carers at the end of the intervention (3 trials, 135 participants; standardised mean difference (SMD) -0.63, 95% confidence interval (CI) -0.98 to -0.28; P<0.001; low-quality evidence). We could not be certain of any effect on clinically significant depressive symptoms (very low-quality evidence). Mindfulness-based stress reduction compared with active control may decrease carer anxiety at the end of the intervention (1 trial, 78 participants; mean difference (MD) -7.50, 95% CI -13.11 to -1.89; P<0.001; low-quality evidence) and may slightly increase carer burden (3 trials, 135 participants; SMD 0.24, 95% CI -0.11 to 0.58; P=0.18; low-quality evidence), although both results were imprecise, and we could not exclude little or no effect. Due to the very low quality of the evidence, we could not be sure of any effect on carers' coping style, nor could we determine whether carers were more or less likely to drop out of treatment. 2. Compared with inactive controls, MBSR showed no clear evidence of any effect on depressive symptoms (2 trials, 50 participants; MD -1.97, 95% CI -6.89 to 2.95; P=0.43; low-quality evidence). We could not be certain of any effect on clinically significant depressive symptoms (very low-quality evidence). In this comparison, MBSR may also reduce carer anxiety at the end of the intervention (1 trial, 33 participants; MD -7.27, 95% CI -14.92 to 0.38; P=0.06; low-quality evidence), although we were unable to exclude little or no effect. Due to the very low quality of the evidence, we could not be certain of any effects of MBSR on carer burden, the use of positive coping strategies, or dropout rates. We found no studies that looked at quality of life of carers or care-recipients, or institutionalisation. Only one included study reported on adverse events, noting a single adverse event related to yoga practices at home After accounting for non-specific effects of the intervention (i.e. comparing it with an active control), low-quality evidence suggests that MBSR may reduce carers' depressive symptoms and anxiety, at least in the short term. There are significant limitations to the evidence base on MBSR in this population. Our GRADE assessment of the evidence was low to very low quality. We downgraded the quality of the evidence primarily because of high risk of detection or performance bias, and imprecision. In conclusion, MBSR has the potential to meet some important needs of the carer, but more high-quality studies in this field are needed to confirm its efficacy.

Plain-language summary: We searched for evidence up to September 2017 and found five randomised controlled trials (clinical trials where people are randomly assigned to one of two or more treatment groups) comparing MBSR to a variety of other interventions. We reported the effects of MBSR programmes compared with active controls (interventions in which participants received a similar amount of attention to those in the MBSR group, such as social support or progressive muscle relaxation) or inactive controls (interventions in which participants received less attention than those in the MBSR group, such as self help education). We were able to analyse study data from five randomised controlled trials involving a total of 201 carers. Findings from three studies (135 carers) showed that carers receiving MBSR may have a lower level of depressive symptoms at the end of treatment than those receiving an active control treatment. However, we found no clear evidence of any effect on depression when MBSR was compared with an inactive control treatment. Mindfulness-based stress reduction may also lead to a reduction in carers' anxiety symptoms at the end of treatment. Mindfulness-based stress reduction may slightly increase carers' feelings of burden. However, the results on anxiety and burden were very uncertain. We were unable to draw conclusions about carers' coping strategies and the risk of dropping out of treatment due to the very low quality of the evidence. None of the studies measured quality of life of carers or people with dementia, or the rate of admission of people with dementia to care homes or hospitals. Only one included study reported on adverse events, noting one minor adverse event (neck strain in one participant practising yoga at home) We considered the quality of the evidence to be low or very low, mainly because the studies were small and the way they were designed or conducted put them at risk of giving biased results. Consequently, we have limited confidence in the results. To summarise, the review provides preliminary evidence on the effect of MBSR in treating some stress-related problems of family carers of people with dementia. More good-quality studies are needed before we can confirm whether or not MBSR is beneficial for family carers of people with dementia.