There is a lot of work done on this by Trevor Robbins and Barbara Sahakian

both at Cambridge, UK. Try them

It depends on the type of MCI: amnestic ( that is the most frequent....) or not. In fact

the part of the brain first impacted is the part related to the impaired cognitive function because the differences between MCI and dementias are quantitative....

In my experience, the "M" in MCI is more commonly considered "Mild" than "Minimal". Some caveats: First, some cognitively normal subjects can be found, after death, to bear surprisingly high levels of amyloid plaque (and to a lesser degree, neurofibrillary tangle- NFT) pathology without manifesting a clinically detected cognitive deficit (I am given to understand that this can a pretty common finding). These are sometimes referred to as "preclinical" or "high pathology" controls. Second, a relatively large subset of MCI patients stay at the MCI stage for their entire long lives without progressing to AD. Third, there are other neuropathological signs worth considering (vascular, synaptic, astroglial, microglial, MRI of various types, even the oft ignored brain weight, to name a few). Finally, among the 'big 2' neuropathological measures, NFTs tend to do a better job of correlating with cognitive changes- see Pete Nelson's meta-analysis (Nelson et al., 2012, J Neuropathol Exp Neurol. 2012 May; 71(5): 362–381). In our hands looking at transcriptional profiles in AD, nothing explained as much variability in the data as mini-mental status exam (a rough measure of cognitive competence) scores (Blalock et al., 2004).

Given those (and I am sure, lots of other) concerns, the canonical stereotypical progression, as measured by looking at the degree to which NFTs have invaded different brain structures, is called Braak staging. The classic reference is Braak and Braak, 1991 (more than 10,000 citations!). Braak staging is broken out into six stages and Serrano-Pozzo, Masliah, and Hyman, 2011 have an excellent (and non-pay walled) paper on AD and neuropathology, and how Braak staging has been incorporated into more recent CERAD and Reagan criteria. Generally, pathology is thought to launch in the entorhinal cortex, go to hippocampal CA1, back out through subiculum, through the lateral entorhinal cortex, then to the nucleus basalis, prefrontal cortex, and then finall back to other neocortical regions..

Eric is correct in that "mild" is the preferred term for MCI (mild cognitive impairment). MCI (minimal cognitive impairment) does appear in journal indices of medical terms, but "mild" may well be considered the preferred term.

Dennis

Dennis Mazur