Mild cognitive impairment

Mild cognitive impairment (MCI) is a diagnosis given to individuals who have cognitive impairments beyond that expected for their age and education, but that do not interfere significantly with their daily activities.^[1] MCI is also used interchangeably with incipient dementia, or isolated memory impairment. It is considered to be the boundary or transitional stage between normal aging and dementia. Although MCI can present with a variety of symptoms, when memory loss is the predominant symptom it is termed “amnestic MCIʺ and is frequently seen as a risk factor for Alzheimer’s disease.^[2] Studies suggest that these individuals tend to progress to probable Alzheimer’s disease at a rate of approximately 10% to 15% per year.^[2] Additionally, when individuals have impairments in other domains other than memory it is classified as Nonamnestic single- or multiple-domain MCI and these individuals are believed to be more likely to convert to other dementias (i.e. Dementia with Lewy Bodies).^[3]

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Diagnosis

The diagnosis of MCI requires considerable clinical judgement,^[2] and as such, a comprehensive clinical assessment including clinical observation, neuroimaging, blood work and neuropsychological testing are best in order to rule out an alternate diagnosis. A similar assessment is usually given for diagnosis of Alzheimer's disease see Alzheimer disease diagnosis.

An individual meets Petersen criteria for a diagnosis of MCI when there is:^[4]

1. Evidence of memory impairment
2. Preservation of general cognitive and functional abilities
3. Absence of diagnosed dementia

Neuropathology

A recent study by Petersen and colleagues, found that while most of the amnestic MCI patients in their study did not meet neuropathologic criteria for Alzheimer's Disease, their pathologic findings suggest a transitional stage of evolving Alzheimer's disease. More specifically, they found diffuse amyloid in the neocortex and frequent Neurofibrillary tangles in the medial temporal lobe structures.^[5]

Treatment

There is no proven treatment or therapy for mild cognitive impairment. As MCI may represent a prodromal state to clinical Alzheimer’s disease, treatments proposed for Alzheimer’s disease, such as antioxidants and cholinesterase inhibitors, may be useful. However, several potential treatments are still under investigations ^[2].

A study by Feldman and colleagues indicated that there was no significant benefit of Rivastigmine (a drug typically used for Alzheimer's disease) on the progression rate to Alzheimer's disease or on cognitive function over 4 years for individuals with mild cognitive impairment.^[6] Furthermore, a study by Birks and Flicker concluded that Donepezil, trade name Aricept, showed no evidence to support the use of Donepezil for patients with mild cognitive impairment as the benefits are minor, short lived, and associated with significant side effects.^[7]

References