Managing cardiometabolic risk factors may help prevent dementia
Changes in cardiometabolic factors such as body mass index (BMI), glucose levels, and blood pressure (BP) may signify dementia risk up to 14 years pre-diagnosis, with management of these risk factors potentially preventing dementia, according to a French population-based study presented at the Alzheimer’s Association International Conference (AAIC 2018).
The researchers conducted up to six home visits, regular assessments of BMI, systolic and diastolic blood pressure (SBP and DBP, respectively), triglycerides, blood glucose, and HDL and LDL cholesterol levels, and neurophysiological tests among 3,925 individuals aged ≥65 years between 1999 and 2014. They identified 785 patients with dementia (cases) – of whom 537 and 162 had Alzheimer’s disease and vascular dementia, respectively – and matched them with 3,140 controls (mean age 76 years, 65 percent female). Cardiometabolic risk factors and medication use were comparable between both groups at baseline, though diabetes (glucose levels ≥125 mg/dL) was present in more cases than controls.
Both cases and controls experienced significant reductions (p<0.001) in mean BMI over the 14-year study period (from 26.1 to 24.8 kg/m2 for cases and from 25.7 to 25.3 kg/m2 for controls), though cases experienced reductions to levels below that of controls 7 years pre-dementia diagnosis, with significantly different values 2.4 years before diagnosis (25.1 vs 25.5 kg/m2; p=0.05). [AAIC 2018, abstract O3-11-02; JAMA Psychiatry 2018;doi:10.1001/jamapsychiatry.2018.2004]
Both cases and controls experienced significant increases (p<0.001) in mean SBP from year 14 to year 0 pre-diagnosis (from 135.2 to 142.1 mm Hg and from 135.8 mm Hg to 144.9 mm Hg, respectively), with SBP increasing at a slower pace in cases than controls and significantly deviating 3.4 years pre-diagnosis. Conversely, mean DBP decreased in both groups (p=0.02), from 76.5 to 74.0 mm Hg among cases and from 76.7 to 75.0 mm Hg among controls, with a significant between-group difference observed at 8.7 years pre-diagnosis.
Mean HDL cholesterol levels also decreased (p<0.001) over the 14-year period among both cases and controls (from 70.6 to 61.3 mg/dL and from 70.4 to 62.3 mg/dL, respectively), while LDL cholesterol and triglyceride levels were relatively stable among patients in both groups (p≥0.15). There was little difference in the trajectories between cases and controls for HDL and LDL cholesterol, and triglyceride levels.
Glycaemic levels increased in both groups (p<0.001) between 14 and 0 years pre-diagnosis (mean fasting glucose levels, from 89.4 to 96.4 mg/dL for cases and from 87.1 to 95.3 mg/dL for controls), with significantly higher levels among cases than controls from 14 to 1.6 years pre-diagnosis.
“[B]oth BMI and BP trajectories of future dementia cases deviated from those of dementia-free controls, leading to lower levels at the approach of diagnosis, whereas trajectories of blood lipid levels remained roughly similar between incident dementia cases and matched controls,” said the researchers.
“Elevated glycemia was the only cardiometabolic risk factor with constantly higher values among dementia cases up to 14 years before diagnosis,” they said.
“[T]here is a biological rationale supporting the interpretation of BMI and BP trajectories in prodromal dementia toward reverse causation because of incipient evolution of neuropathologic changes and subtle cognitive impairment,” said the researchers. “Yet, because low BP may cause hypoperfusion and lead to brain damage, the lower BP in prodromal dementia may also reflect a causal association,” they said, though they recommended caution when interpreting the findings due to the observational design of the study.
They also pointed out that the results of this study – conducted in three cities in France among mostly urban populations – may not necessarily be applicable to other populations, and that the study only goes back 14 years pre-dementia diagnosis and as such, may not apply to preventive measures in early adulthood.
“[Nonetheless,] these findings emphasizing blood glucose control, low BP, and weight loss as key components of cardiovascular health management for primary and secondary prevention of dementia in older persons may have important implications for preventive care practice in geriatric populations,” they said.