Cost utility and cost-effectiveness of the APPLE-Tree programme: Active Prevention in People at risk of dementia through Lifestyle, bEhaviour change and Technology to build REsiliEnce: economic evaluation embedded within a randomised controlled trial.

TL;DR

A multi-domain dementia prevention program targeting people with early cognitive changes produced small but meaningful cognitive improvements over 2 years, with cost-effectiveness comparable to other health interventions . Quality-of-life gains were minimal, but the intervention may be particularly valuable for socioeconomically disadvantaged groups.

What the Study Found

The APPLE-Tree trial enrolled 746 older adults (mean age not specified in abstract) experiencing subjective cognitive decline or mild cognitive impairment from English health and community settings. Half received a personalized, multi-domain intervention delivered with low intensity and technology support, plus usual care. The other half received usual care plus written dementia prevention information. The researchers followed participants for 24 months and measured both cognitive outcomes and healthcare costs.

On the Neuropsychological Test Battery (NTB), the intervention group showed a small adjusted advantage: a 0.06 z-score improvement over control. This difference was statistically modest (95% confidence interval crossed zero at -0.001), but the authors note it aligns with previous research suggesting a 1-point NTB gain associates with approximately three-fold reduction in 5-year dementia risk. The practical meaning of this 0.06-point difference remains uncertain, as it falls below the threshold of established clinical significance.

The cost-effectiveness picture was mixed. From a quality-of-life perspective measured by standard health economics metrics (QALYs via EQ-5D-5L), APPLE-Tree did not show benefit. The intervention group had slightly lower quality-adjusted life-years (1.511 vs 1.520), a difference of -0.010 that was not favorable. Healthcare and social care costs ran about 400 pounds higher for the intervention group (2,966 vs 2,551 pounds over 24 months). When evaluated purely on QALY gains, the intervention had only a 12% probability of being cost-effective at the standard 30,000-pound threshold used in UK health policy.

However, when the researchers evaluated cost-effectiveness through the lens of cognitive gain alone, the picture shifted substantially. The incremental cost per 1-point NTB z-score change was 6,809 pounds, which carried a 96% probability of cost-effectiveness at the 30,000-pound threshold. This difference in interpretation hinges on a fundamental question in dementia prevention research: should we prioritize general quality-of-life measures, or can we rely on cognitive test improvements as valid indicators of clinically meaningful benefit? The authors implicitly suggest the latter may be defensible given the association between NTB changes and dementia risk reduction, though this remains an open debate in the field.

A notable secondary finding emerged in post-hoc analyses examining subgroups. The intervention appeared substantially more cost-effective in non-White participants and socioeconomically disadvantaged adults (defined as non-homeowners). This group saw lower overall costs (-1,830 pounds), higher QALYs (0.106 advantage), and achieved 98% probability of cost-effectiveness at a 20,000-pound threshold. This suggests either that the intervention was genuinely more effective for these populations, or that these groups had greater room for improvement at baseline. The authors acknowledged that longer-term follow-up data is essential to determine whether the observed cognitive gains translate into sustained dementia risk reduction and whether cost-effectiveness improves over time horizons beyond 2 years.

What This Means for You

If you are experiencing early cognitive concerns or have risk factors for cognitive decline, this study suggests that multi-domain, low-intensity interventions can produce measurable cognitive effects without major time or financial burden. The program combined behavioral change, lifestyle strategies, and technology support, which aligns with established dementia prevention approaches.

The cost per cognitive point gained (6,809 pounds) is reasonably competitive with other health interventions, though this metric matters most to healthcare systems rather than individuals. More practically: the intervention costs were modest in absolute terms (roughly 415 pounds extra over 2 years), and no safety signals emerged.

The subgroup finding is important: if you are from a socioeconomically disadvantaged background or non-White population, the evidence suggests you may see substantially better results than the overall population average. This could reflect either tailoring effects or greater baseline need. Conversely, the lack of broad quality-of-life improvement suggests this intervention is specifically a cognitive protection strategy, not a general wellness program.

One caveat: we lack 5-year or 10-year follow-up data. The study demonstrates cognitive benefit over 2 years, but does not yet show whether this translates into actual dementia risk reduction in real time. The theoretical association between a 1-point NTB gain and three-fold dementia risk reduction is compelling but requires prospective validation.

Study Details

Sources

Malouf R, et al. Cost utility and cost-effectiveness of the APPLE-Tree programme: Active Prevention in People at risk of dementia through Lifestyle, bEhaviour change and Technology to build REsiliEnce. Age Ageing. 2025. PMID: 42328805