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ACE inhibitors ‘slow cognitive decline’ in dementia

Treatment with centrally-acting ACE inhibitors slows cognitive decline slightly among patients with dementia, and may even boost their cognitive performance when they first start the treatment, shows a case–control study of outpatients attending two university memory clinics in Canada.

The study

Researchers studied a total of 361 patients, with an average age 77 years, who had been diagnosed with Alzheimer’s disease, vascular dementia, or a mix of both.

Eighty five patients were already taking centrally-acting ACE inhibitors, which cross the blood–brain barrier, and a further 30 patients were newly prescribed the drugs at the start of the study.

The researchers assessed patients’ performance on two standard tests of cognitive function – the Standardised Mini Mental State Examination (SMMSE) or the Quick Mild Cognitive Impairment (Qmci) screen – at baseline and again at six months.

The findings

Patients already taking the ACE inhibitors had a marginally slower rate of cognitive decline over the six months than those who were not taking the drugs, with a median increase (worsening) in SMMSE score of 0.8 versus 1.0, and a median Qmci score increase of 1.8 versus 2.1, respectively.

The difference in median rate of cognitive decline over six months reached borderline statistical significance when judged by the Qmci score.

In the group newly taking ACE inhibitors, there was a significant improvement rather than decline in cognitive performance, with a median reduction in SMMSE score of 1.2; this change was statistically different from the change in SMMSE in both those patients already taking ACE inhibitors and those not taking them. The researchers speculated that the improvement in cognitive impairment among newly treated patients could be down to ‘better medication compliance, the effects of improved blood pressure control or increased cerebrovascular perfusion after initial treatment’.

What this means for GPs

The researchers concluded: ‘This [study] supports the growing body of evidence for the use of ACE inhibitors and other [blood pressure lowering] agents in the management of dementia.

‘Although the differences were small and of uncertain clinical significance, if sustained over years, the compounding effects may well have significant clinical benefits.’

However, they caution that some previous evidence has suggested ACE inhibitors could actually increase cognitive decline and mortality in patients with cognitive impairment, ‘suggesting that if ACE inhibitors are proven to be beneficial in dementia, not all patients will benefit’.

BMJ Open 2013; 3: e002881