Question:
The role of blood pressure (BP) as a risk factorfor dementia is complex and may be age dependent. In very oldindividuals, low BP might increase risk for dementia, perhaps byreducing cerebral perfusion pressure. METHODS: The association betweenBP and dementia was examined in the Bronx Aging Study, a prospectivestudy of 488 community-dwelling elderly individuals over age 75,dementia-free at baseline (1980 to 1983) and followed at 12- to18-month intervals. Subjects with baseline BP and with at least onefollow-up visit were included (n = 406). Incident dementia wasdiagnosed using the criteria of the Diagnostic and Statistical Manualof Mental Disorders (3rd rev. ed.). RESULTS: Over 21 years (median 6.7years), 122 subjects developed dementia (65 Alzheimer's disease [AD],28 vascular dementia, 29 other dementias). Relative risk of dementiaincreased for each 10-mm Hg decrement in diastolic (hazard ratio [HR]1.20, 95% CI 1.03 to 1.40) and mean arterial (HR 1.16, 95% CI 1.02 to1.32) pressure, adjusted for age, sex, and education. Low diastolic BPsignificantly influenced risk of developing AD but not vasculardementia. Upon examination of groups defined by BP, mildly tomoderately raised systolic BP (140 to 179 mm Hg) was associated withreduced risk for AD (HR vs normal systolic BP group 0.55, 95% CI 0.32to 0.96), whereas low diastolic BP (What's your opinion??

Answer: I don't think this should concern most of us as much as it appears tohave done for the two posters who so far thought it was "scary".The result of low blood pressure on brain perfusion depends entirely onthe *reason* for the low blood pressure. If one's blood pressure is lowbecause of flexible arteries without any plaque, calcification of otherflow constrictions, then I fail to see how this will lead to poor brainperfusion (and therefore to the dementia caused by it).

In the elderly low blood pressure can also be caused by general bodyweakening, loss of vitality and frailty, particularly a weakening of theheart muscle. I had not thought about this before, but it is evenpossible that higher blood pressure when younger cause by arterialocclusions may help the heart muscle remain stronger for a longer timebecause it is constantly getting more exercise. (This is just a wildthought.)

The other reason for problems with the elderly is that they often havepoor oxygenation of the blood due to dysfunctional lungs and shallowbreathing. This poor oxygenation *combined* with low blood pressure iscertainly not good. However, once again if one exercises and neversmokes and eats well (including certain specialized nutrients), one willkeep one's lungs in top shape and continue to get good oxygenation intoold age.