Dementia prevalence in a population at high vascular risk: the Trinidad national survey of ageing and cognition.

OBJECTIVE

To investigate the dementia prevalence in a country with high levels of cardiovascular risk factors DESIGN AND METHODS: Older people in Trinidad are recognised to have particularly high levels of cardiovascular risk factors. We carried out a survey in a nationally representative sample of people aged ≥70 years using household enumeration. Dementia status was ascertained using standardised interviews and algorithms from the 10/66 schedule and age-specific prevalence were compared with identically defined output from the 10/66 surveys of 16 536 residents in eight other low-income and middle-income countries.

RESULTS

Of 1832 participants (77.0% response rate), dementia was present in 442 (23.4%). Prevalences were 12.0% in persons aged 70-74 years, 23.5% at 75-79, 25.8% at 80-84, 41.3% at 85-89 and 54.0% in those aged ≥90 years. Prevalence ratios compared with averages from 10/66 surveys in these age groups were 2.2, 2.6, 1.6, 1.7 and 1.6, respectively, and were 2.7, 2.8, 1.7, 1.4 and 0.8, respectively, compared with previously published consensus estimates for the Latin American region. Dementia was significantly associated with reported stroke and diabetes in logistic regression models adjusted for sociodemographic status and other vascular risk factors (OR (95% CI) 4.40 (2.70 to 7.19) and 1.56 (1.20 to 2.03), respectively). Projected national numbers of people with dementia (18 206) were 70%-100% higher than those estimated using most recent regional consensus prevalences.

CONCLUSION

In a nation with high levels of vascular risk, dementia prevalence is higher than expected, particularly at the lower end of the 70+ age range. International prevalence projections may need to take into account risk status as well as age structures.