Latin America takes centre stage in dementia prevention.

Abstract

The study of Alzheimer's disease has placed Latin America at the forefront of dementia research. In Colombia, researchers have focussed on autosomal dominant Alzheimer's disease, while in Argentina and Brazil, their colleagues have been working hard to promote prevention of sporadic disease (ie, primary prevention). The wider region is now taking centre stage in both inherited and sporadic dementia prevention. As announced on July 30 at the Alzheimer's Association International Conference (AAIC 2020), the LatAm-FINGERS trial will commence before the end of the year. The trialists have the ambitious aim of tackling primary prevention of dementia throughout the continent. Over the past decade, European initiatives led the clinical research on primary prevention. The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) marked an inflection point, showing that prevention could be a realistic aspiration. This trial tested whether a multidomain intervention (diet, exercise, cognitive training, and cardiometabolic risk management) could prevent cognitive decline in people aged 60–77 years. Cognitive decline was less in those randomised to the intervention than in controls, who received only general health advice. The between-group difference in cognitive scores per year was small, but statistically significant, and the effect could have considerable impact if replicated in the real world. Participants in the FINGER trial were deemed to be at high risk of dementia, due to their age and cardiovascular risk factors. This latter criterion is relevant, as risk reduction seems to be most efficacious when interventions target the people carrying such risk. The Dutch Prevention of Dementia by Intensive Vascular Care (PreDIVA) study found no benefit to targeting cardiovascular factors in participants selected according to age (70–78 years) only. The FINGER intervention was more intensive than those used in other pioneering trials, like the Multidomain Alzheimer Preventive Trial (MAPT), suggesting that targeting several risk factors simultaneously and vigorously can optimise benefit. Building on the foundation provided by these studies, the World Wide FINGERS network was launched at AAIC 2017 to tackle the prevention of cognitive impairment globally. By 2018, the network had planned trials—with harmonised methods based on the interventions of the original FINGER—in Australia, China, Singapore, the USA, the UK, and several European countries. These ongoing studies have informed the design of LatAm-FINGERS, which is the network's largest project so far. LatAm-FINGERS will recruit 1300 participants in 13 countries, from Argentina to Mexico. The study will also compare the effects of health advice (control arm) with those of the multidomain intervention, which has been locally adapted. Diet and exercise interventions will be country-specific, to accommodate local habits and cultural preferences. Nevertheless, diets must comply with MIND-diet guidelines (regarding caloric intake, proportion of fats versus carbohydrates, etc) and exercise programmes will be standardised regarding recurrence, intensity, and proportion of aerobic, strength, and balance training. Some participants might have low educational attainment, and cognitive training is perhaps the most challenging intervention. The trial will test a digital cognitive stimulation platform, adapted from the U.S.-POINTER study, which is the network's ongoing trial in the USA. After 1 year, LatAm-FINGERS will assess the feasibility of the multidomain intervention in its large and heterogeneous geographical setting. If feasibility outcomes are positive, the trial will be extended for another year, but the expectation is that the first 12 months will suffice to detect a change in cognitive scores (the primary outcome). The Lancet Standing Commission on Dementia prevention, intervention, and care, launched at AAIC 2020, recommends to “be ambitious about prevention”. It proposes a life-course model of dementia prevention, in which a dozen modifiable risk factors are responsible for about 40% of the population attributable fraction of dementia worldwide. Excessive alcohol consumption, obesity, and hypertension in midlife (45–65 years), and diabetes and sedentarism in later life are among these factors. A major limitation of the model is that most data were obtained in Europe and North America, although the Commission recognises that the “potential for prevention is high and might be higher in low-income and middle-income countries, where more dementias occur”. Dementia prevalence is high and expected to increase in Latin America because of rapid population ageing; the increase might accelerate if risk factors continue to rise. When the start-up phase of LatAm-FINGERS begins in November, Latin America will carry the baton forward in dementia prevention.