Mild Cognitive Impairment

You have arrived at a determination that an individual likely has MCI or Mild Cognitive Impairment.

MCI may be related to one cognitive domain such as amnestic MCI, in which only (or primarily) short-term memory is impaired. MCI may also be associated with other types of cognitive impairment, and multiple aspects of cognition may be impaired. Regardless of the MCI subtype, there is a substantial risk that an individual with MCI will progress from a minor neurocognitive disorder (synonymous with MCI) to a major neurocognitive disorder (synonymous with dementia). The likelihood of progression from MCI to dementia is estimated to be between 25 to 40%, depending on which population has been studied. Clinically, we often simplify this variability and simply tell our patients that there is roughly a 1/3 chance of progression from MCI to dementia. We use this information to justify bringing them back for more testing, sometimes invasive testing like a spinal fluid examination (lumbar puncture), or amyloid PET scan.

The purpose of this entire algorithm is to explain how we use the p-tau 217 blood test to help us identify appropriate candidates for anti-amyloid therapy in the DNAC, and to do so with scientific rigor.

As we move forward in the algorithm, you should bear in mind that no biomarker is perfect, just as no clinical indicators are perfect at the MCI stage. Many unanswered questions remain:

• What impact does the prevalence of AD in the DNAC’s MCI population have on this figure?
• Does the clinical referral population impact the probability of AD among DNAC patients referred for consideration of anti-amyloid therapy?
• How well does the p-tau 217 blood test predict who is likely to have MCI due to AD?
• Are there other biomarkers that may be superior to p-tau 217 in distinguishing MCI due to AD among DNAC patients identified to have MCI?
• What are the potential risks of a false positive or false negative test result from cognitive screening, or from such biomarker tests?
• What are the individual's views on testing after we Discuss Treatment Options with Anti-amyloid Agents?

Bearing all these questions in mind, let’s go ahead and do P-tau217 Testing.