Transtheoretical Model (TTM)-Based, TTM-Informed and TTM-Congruent Behaviour Change Interventions for Adults with Mild Cognitive Impairment and Dementia Risk: A Scoping Review

Background/Objectives: Mild cognitive impairment (MCI) is a clinically important state associated with an increased risk of future cognitive decline and dementia. Behaviour change interventions may support risk reduction and self-management in cognitively vulnerable adults. However, the extent to which the transtheoretical model (TTM) has been used in this population has not been clearly mapped. This scoping review examined TTM-based, TTM-informed, and TTM-congruent behaviour change interventions for adults with MCI, subjective cognitive concerns, or elevated dementia risk. Methods: This scoping review followed Joanna Briggs Institute guidance and was reported in accordance with PRISMA-ScR. The protocol was prospectively registered on the Open Science Framework. PubMed, PsycINFO, ScienceDirect, Scopus, Web of Science, CENTRAL, ProQuest Dissertations, and medRxiv were searched from inception to 30 September 2025. Eligible studies included randomised, nonrandomised, quasi-experimental, and qualitative designs. Data were charted using a piloted extraction form and were synthesised narratively. Results: Eight unique studies, represented across nine publications, were included. Only one trial explicitly operationalised the TTM in a clinically defined MCI cohort; most studies were more appropriately classified as TTM-informed or TTM-congruent. Recurrent intervention components included readiness alignment, goal setting, self-monitoring, personalised feedback, prompts and cues, problem solving, reinforcement, and relational support. Behavioural outcomes were more consistently favourable than cognitive outcomes, particularly for adherence, self-management, diet, and sustained physical activity engagement. Cognitive findings were heterogeneous: some smaller studies reported short-term improvements, whereas the largest rigorous trial found no significant cognitive benefit. Conclusions: Current evidence does not support strong claims regarding TTM-specific cognitive efficacy in MCI. Instead, it suggests that TTM-informed and TTM-congruent interventions may be useful for strengthening behavioural regulation, risk reduction, and maintenance of health-related routines in cognitively vulnerable adults. More rigorous studies are needed to test the TTM constructs prospectively and to determine whether proximal behavioural change translates into durable cognitive or functional benefit.