Vascular interventions may not reduce dementia incidence

Interventions that targeted vascular risk factors in a real-world setting did not appear to reduce dementia incidence in old age, according to study results in a research letter published in JAMA Neurology.

Researchers evaluated these interventions in the pragmatic multidomain Prevention of Dementia by Intensive Vascular Care (preDIVA) trial.

“PreDIVA is the first and only trial aiming at real-world evidence of dementia prevention, in contrast to short-term trials with intermediate outcomes, such as cognitive decline,” Marieke P. Hoevenaar-Blom, PhD, of the department of public and occupational health, Amsterdam UMC, University of Amsterdam, the Netherlands, told Healio Neurology. “After 6 to 8 years of multidomain intervention, there was no significant effect on dementia. Because dementia takes years to develop, it was important to investigate whether an effect would occur after a longer follow-up period.

“However, follow-up after more than 10 years, comprising over 30,000 person-years, failed to provide evidence of dementia prevention,” Hoevenaar-Blom added.

Epidemiological studies have shown an association between modifiable risk factors and up to 40% of dementia cases; however, no consistent evidence has shown preventive or delaying effects on dementia related to multidomain interventions that target these risk factors.

In the current research letter, Hoevenaar-Blom and colleagues reported the results of the preDIVA trial following an extended observational follow-up period of up to 12 years after baseline. A total of 3,526 participants aged 70 to 78 years without dementia participated in the trial after being recruited from the general population between 2006 and 2009. Of these participants, 4% scored less than 24 points on the Mini-Mental State Examination. The researchers randomly assigned participants to either a practice nurse-administered multidomain intervention that focused on vascular risk factors, such as smoking, unhealthy diet, physical inactivity, overweight, hypertension, dyslipidemia and diabetes, or usual care during the 6- to 8-year period.

During a maximum of 4 years of observational follow-up, Hoevenaar-Blom and colleagues assessed dementia status among all participants who survived without dementia in the trial phase, which resulted in a median follow-up of 10.3 years since random assignment. They labeled as having no dementia surviving participants who scored greater than 30 on the Telephone Interview of Cognitive Statue and who did not have a formal dementia diagnosis. Further, the researchers searched the general practitioners’ electronic health records for information on possible dementia in all other cases.

Hoevenaar-Blom and colleagues identified 176 participants diagnosed with dementia during observational extension, as well as 233 participants diagnosed with dementia during the trial phase. A total of 217 of 1,871 intervention participants (11.6%) developed dementia compared with 192 of 1,620 control participants (11.9%) (HR = 0.99; 95% CI, 0.89-1.1) since baseline. The researchers reported no statistically significant interactions for sex, age, cardiovascular history, apolipoprotein e4 genotype, hypertension or hypercholesterolemia in intention-to-treat and per-protocol subgroup analyses. A total of 561 participants (29.7%) died in the intervention group compared with 487 (29.8%) in the control group (HR = 0.97; 95% CI, 0.92-1.04). They found similar results for the intervention effect on dementia, according to results of Fine-Gray models that factored in the competing risk for death.

“For clinical practice, prevention of dementia is not an easy task in older people already having access to good preventive health care,” Hoevenaar-Blom said. “For researchers, we showed that pragmatic trials are feasible that are sufficiently powered, with long-term follow-up and with dementia as the primary outcome. Future research is warranted in populations at higher risk, at younger ages or in countries with less developed preventive health care.”