Caution against over-intensive BP control in diabetes patients

By Eleanor McDermid, Senior medwireNews Reporter

Very intensive control of blood pressure (BP) in patients with Type 2 diabetes does not prevent cognitive decline and may even be counterproductive, suggest findings from the ACCORD MIND substudy.

The MIND (Memory in Diabetes) substudy tracked the cognition and total brain volume of a group of participants in ACCORD (Action to Control Cardiovascular Risk in Diabetes), which investigated the effects of intensive risk factor control in patients with diabetes.

The substudy previously showed that tight glycaemia control did not affect participants’ cognitive outcomes, relative to standard control, and the latest analyses of two further studies nested within the MIND substudy show the same lack of benefit for treating systolic BP (SBP) to a target of 120 mmHg and for combination treatment of lipid levels.

A total of 1274 patients in the BP-lowering study undertook the Digit Symbol Substitution Test (DSST) at baseline and after 40 months of follow-up. The average DSST score declined slightly over this period, from 52.3 to 50.4 in patients treated to a target of 120 mmHg and from 52.3 to 50.7 in those treated to the standard target of 140 mmHg, with the difference between the groups nonsignificant.

And neither did the BP treatment target affect outcomes for the Stroop test, the Mini-Mental State Examination or the Rey Auditory Verbal Learning Test.

However, intensive BP control appeared to have an adverse effect on brain volume, report Jeff Williamson (Wake Forest School of Medicine, Winston-Salem, North Carolina, USA) and team in JAMA Internal Medicine.

Among 314 patients in the BP-lowering study who also underwent baseline and 40-month magnetic resonance imaging, total brain volume fell from a baseline of 921.5 cm³ to 902.6 cm³ in the intensive-treatment group and 907.0 cm³ in the standard-treatment group. The reductions from baseline, of 18.9 and 14.5 cm³, respectively, were significantly different.

In an accompanying commentary, Carole Dufouil (INSERM, Bordeaux, France) and Carol Brayne (University of Cambridge, UK) say: “Treatment effects are first seen on structure and then on function if the follow-up of participants is long enough.”

Given that brain atrophy is closely tied to dementia, longer follow-up could therefore reveal adverse effects of intensive BP control on cognition.

“The potential for adverse outcomes with tight BP control suggests that, with greater knowledge about the effect of BP on dementia risk during the life course, enthusiastic control of BP later in life should be pursued with caution and based on existing evidence, not extrapolated benefits,” they conclude.

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