Time trends in the relation between blood pressure and dementia in 85-year-olds

Blood pressure has decreased in the general population. We aimed to examine whether this is true also among the very old, and among persons with and without dementia. Further, we aimed to investigate how common undetected and untreated hypertension is in the very old, both among people with and without dementia.

Blood pressure was measured in representative population samples of 85-year-olds living in Gothenburg, Sweden, examined 1986-1987 (n = 484) and 2008-2010 (n = 571). Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, edition 3 revised, by the same medical doctor at both examinations.

Both systolic and diastolic blood pressure were lower in 85-year-olds examined 2008-2010 than in those examined 1986-1987, both among those with and without dementia. Participants with dementia had lower systolic blood pressure than those without dementia in both cohorts, and blood pressure levels related to dementia severity. Despite this, hypertension (≥140/90 mmHg) was found in almost half (46.5%) of those with dementia in 2008-2010.

Our findings show that time-trends of lower blood pressure in western populations also applies to the very old, and that individuals with dementia continue to have lower blood pressure compared to the rest of the population. The latter finding suggests that the pathophysiological processes in dementia affect blood pressure regulating regions in the brain independent of time trends. Still, hypertension is common in dementia and needs to be detected and treated.