Discriminating AD From MCI by Using MR and CSF Data

When attempting to discriminate among Alzheimer disease (AD), mild cognitive impairment (aMCI),* and normal cognition, structural abnormalities on MR images are more useful than known CSF biomarkers; but the use of both together is more diagnostically helpful than each individually. This conclusion is based on data from the Alzheimer Disease Neuroimaging Initiative, now available in the latest issue of Neurology.

In a statistical analysis of data from 399 subjects, the degree and location of AD-related brain atrophy on 3D MR images (condensed into the so-called Structural Abnormality Index, or STAND, score) correlated with clinical measures of cognition (eg, the MMSE score). However, known CSF biomarkers for AD—total tau, amyloid beta(1-42), and phosphorylated tau(181P)—did not. Nevertheless, the diagnostic accuracy for AD was best with the combined use of the STAND score, CSF total tau, and CSF amyloid beta. (Measures of total tau are expected to directly reflect neurofibrillary tangle pathology in AD.) In a related study, the STAND score was also a better predictor of clinical cognitive decline—namely the progression of aMCI to AD—than CSF biomarkers.

The Alzheimer Disease Neuroimaging Initiative is a longitudinal, multisite, observational study of elderly individuals with normal cognition, aMCI, or AD at 56 US or Canadian institutes. Funding for the study originates from the National Institute of Aging, the National Institute of Bioimaging and Bioengineering, pharma, and "several foundations."

CSF = cerebrospinal fluid; MMSE = Mini-Mental State Examination; MR = magnetic resonance.

* Amnestic mild cognitive impairment.

Photograph: Atrophied brain of person with AD from National Institute on Alcohol Abuse and Alcoholism.