Mild Cognitive Impairment - A Crystal Ball?
In the grey zone between benign forgetfulness associated with normal, healthy aging and the memory loss associated with Alzheimer’s Disease (AD), lies an intermediary condition known as mild cognitive impairment, or MCI. A person with MCI will experience greater memory problems than would be expected for his or her age and education, but would not suffer from the pronounced personality changes or cognitive problems (e.g. in the domains of learning, reasoning, decision-making) that characterize Alzheimer’s Disease, and would have ‘no significant daily functional disability’. According to Baycrest, individuals diagnosed with MCI have a 50% risk of developing AD within 5 years.
Since the introduction of the term MCI, two key questions have arisen:
i) How should MCI be diagnosed?
ii) Can we predict which individuals with MCI will go on to develop AD?
Clinical Diagnosis
The mechanisms by which MCI is diagnosed vary widely. Some physicians use the same diagnostic tests as those for diagnosing dementia; i.e. history-taking, physical examination, brief cognitive testing and possibly lab tests to rule out other reversible causes of memory loss. These tests are sometimes supplemented with imaging tools such as PET scans, CT scans and the MRI. In terms of cognitive screening tools, the Mini-Mental Status Examination has been shown to have low sensitivity to detect MCI while in contrast, the Montreal Cognitive Assessment has high sensitivity to detect MCI.
Risk of Progression
Research has demonstrated that there are measurable changes in people suffering from Alzheimer’s Disease many years before symptoms appear. Recent strides have been made in testing for these early changes, which include loss of brain volume and a reduction of a protein called amyloid in the cerebrospinal fluid.
It is estimated that 8% of Canadians over the age of 65 have dementia.
Jennifer Hartman, guest blogger
