Pathological changes of dementia are thought to commence in mid-life, making mid-life an attractive target for dementia risk reduction. This review assessed the current literature on multidomain dementia risk-reduction interventions in mid-life.

We systematically searched MEDLINE, CINAHL and EMBASE for eligible studies. Studies were included if (i) participants had a mean age between 45 and 65 years, (ii) the intervention was delivered in a primary care setting and targeted two or more dementia risk factors, and (iii) outcomes were change in cognitive function or change in risk score. Data was extracted and assessed for bias using the revised Cochrane risk-of-bias assessment tool.

Seven studies were included. Participants' mean age ranged from 45.3 to 64.2 years. Interventions ranged from 10 weeks to 9.8 years and targeted between two and six dementia risk factors. There was a large variation in the type of outcome and statistical tests utilised across the included studies, impacting the ability to draw comparisons between the studies and draw conclusions regarding treatment effects. There was a high risk of bias in three of the studies and some concerns of bias in the other four studies. Two studies assessing dementia risk found a reduction in risk scores at their primary endpoint. None of the included studies found a statistically significant change in cognition from their interventions. This may be attributable in part to not assessing cognition prior to the interventions, limited risk factors being addressed, and the short follow-up/duration of the studies.

Current evidence for multidomain dementia risk-reduction interventions in mid-life is not definitive; however, given their substantive potential benefits and likely limited harms, they may be considered for implementation in clinical practice after further evaluation. Future trials that have longer follow-ups, target a broader range of dementia risk factors, and that use consistent outcome measures will be valuable. Strategies to maximise implementation of multidomain interventions and long-term effectiveness will enhance the evidence base for dementia prevention in primary care.