Angiotensin-converting enzyme (ACE) inhibitors are important for control of blood pressure and have made a profound impact on patients with diabetes and congestive heart failure. The ACE inhibitors, which act outside the brain, have had minimal impact on dementia of any cause. However, there is now evidence indicating that ACE Inhibitors which act inside the brain, may have the ability to reduce cognitive decline.
Recent observational data from the Cardiovascular Health Study revealed that that centrally active ACE inhibitors did diminish cognitive decline by 65% per year of exposure, an effect that is likely related to the drug’s ability to cross the blood-brain barrier.
The study included 414 subjects who had been administered ACE inhibitors and 640 who had taken other antihypertensive medications. The researchers found no connection between exposure to all ACE inhibitors and risk for dementia, difference in cognitive-function scores, or odds of disability. However, further analysis according to type of ACE inhibitor showed an unusual benefit. The results revealed that centrally active ACE inhibitors were associated with 65% less decline in cognitive-function scores per year of exposure.
This lessening in cognitive decline is not felt to be due to better control of blood pressure but most likely related to the drug’s effects on the brain's intrinsic renin-angiotensin system, which is felt to be valuable in memory and cognition. There is some laboratory evidence showing that stimulation of the renin-angiotensin system also provokes activation of inflammatory mediators which have been implicated in causing degenerative dementias.
For patients with dementia, this may be good news. There has been a huge public demand to find an intervention that can prevent or slow cognitive decline. However, the above study has to confirmed in a randomized clinical trial to determine if the above results are in fact a true observation.