We appreciate the comments raised by Kawada (1) on our recent article (2) regarding one of our study’s findings that hypertension appeared to be protective rather than a risk factor for the incidence of dementia. We agree that this result is somewhat paradoxical and counterintuitive given that prior cardiovascular conditions (stroke, coronary artery disease, and peripheral vascular disease) and chronic kidney disease were associated with a greater risk of dementia. We speculated whether this apparent protective relationship might relate to treatment effects, for example, greater blood pressure lowering in those with diagnosed hypertension or the use of specific blood pressure–lowering medications that are intrinsically protective against dementia. Once we adjusted for medication use, the effect of hypertension became neutral; however, current calcium channel blocker use (and statin use) was associated with a lower incidence of dementia. Although our hypertension algorithm is highly specific for identifying individuals with diagnosed hypertension (3), it is possible that physicians who submit more service claims for hypertension management are more likely to recognize, treat, and follow such patients and therefore may also treat hypertension to lower targets. Unfortunately, we were unable to examine the impact of blood pressure levels on the risk of dementia directly and therefore could not disentangle the effects of blood pressure itself from its treatment. In response to further points raised by Kawada, we agree that our study’s findings would have been strengthened if we had separately examined the relationship between diabetes and vascular dementia, Alzheimer disease, and mild cognitive decline. As mentioned in the discussion section of our article, we did not have a validated measure for each of these outcomes and therefore felt unable to adequately discriminate between these conditions. We also were unable to assess the relationship between clinical measures such as A1C levels and the development of dementia, but we will be interested to repeat our analyses once these types of measures become available in our data sets.
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Duality of Interest. No potential conflicts of interest relevant to this article were reported.
