The NEJM Resident e-Bulletin is one of the ways I keep up with medical information.  While it will not be possible for me to reproduce every email that comes from this service, on occasion I will post topics of interest.  Copyright remains vested with the NEJM so don’t try and steal this to make money.

Teaching Topic

Mild Cognitive Impairment

Clinical Practice

Mild Cognitive Impairment

R.C. Petersen

     

MCI represents an intermediate state of cognitive function between the changes seen in aging and those fulfilling criteria for dementia, often Alzheimer’s disease (AD).

Clinical Pearls

  What is the estimated prevalence of MCI?

The estimated prevalence of MCI in population-based studies ranges from 10 to 20%. In the Mayo Clinic Study of Aging, a prospective, population-based study of non-demented persons ages 70 to 89 years at enrollment, the prevalence of amnestic MCI was 11.1% and of nonamnestic MCI, 4.9%.

  How can the “worried well” be differentiated from patients with MCI?

Neuropsychological testing may be necessary to corroborate a history of decline in cognition, usually memory. At times, the “worried well” can give a convincing history for memory loss, but neuropsychological testing reveals normal performance.

Figure 1. Diagnostic Algorithm for Amnestic and Nonamnestic Mild Cognitive Impairment.

Morning Report Questions

Q. What factors predict a more rapid progression of cognitive impairment among patients with MCI?

A. As compared with the incidence rate for dementia in the general population of 1 to 2% per year, the incidence of dementia in patients with MCI is significantly increased, with an annual rate of 5 to 10% in community-based populations and 10 to 15% in clinic-based populations. The degree of cognitive impairment at presentation is a clinical predictor of progression; those with greater baseline impairment appear more likely to progress more rapidly. The presence of the apolipoprotein E ε4 allele is also predictive of progression rate. Several MRI measures have also been reported to predict a faster rate of progression, including atrophic hippocampi, dilated ventricles, reduced total brain volume, and the presence of white matter hyperintensities.

Q. How can patients with MCI be managed?

A. Limited data support the potential benefit of cognitive rehabilitation approaches. Several clinical trials that treated persons with MCI with cholinesterase inhibitors used for AD (donepezil, galantamine, and rivastigmine) at standard AD treatment doses for 2 to 4 years have shown no significant reduction in the rates of progression to dementia.