Providing some support for the finding I recently reported — that problems with semantic knowledge in those with mild cognitive impairment (MCI) and Alzheimer’s might be rooted in an inability to inhibit immediate perceptual information in favor of conceptual information — a small study has found that executive function (and inhibitory control in particular) is impaired in far more of those with MCI than was previously thought.
The study involved 40 patients with amnestic MCI (single or multiple domain) and 32 healthy older adults. Executive function was tested across multiple sub-domains: divided attention, working memory, inhibitory control, verbal fluency, and planning.
As a group, those with MCI performed significantly more poorly in all 5 sub-domains. All MCI patients showed significant impairment in at least one sub-domain of executive functioning, with almost half performing poorly on all of the tests. The sub-domain most frequently and severely impaired was inhibitory control.
The finding is in sharp contrast with standard screening tests and clinical interviews, which have estimated executive function impairment in only 15% of those with MCI.
Executive function is crucial for many aspects of our behavior, from planning and organization to self-control to (as we saw in the previous news report) basic knowledge. It is increasingly believed that inhibitory control might be a principal cause of age-related cognitive decline, through its effect on working memory.
All this adds weight to the idea that we should be focusing our attention on ways to improve inhibitory control when it declines. Although training to improve working memory capacity has not been very successful, specific training targeted at inhibitory control might have more luck. Something to hope for!
 The Profile of Executive Functioning in Amnestic Mild Cognitive Impairment: Disproportionate Deficits in Inhibitory Control. Journal of the International Neuropsychological Society. 2012 ;FirstView:1 - 15.