Another Week, Another Study of CSF Biomarkers in Alzheimer's

This time German physicians are proposing that higher CSF concentrations of the soluble amyloid precursor protein beta (sAPPβ), not the endproduct amyloid beta 1-42, are better at predicting which patients with MCI will progress onto AD. Furthermore the marker appears to be useful for distinguishing AD from other dementias, like frontotemporal dementia (FTD). This new iteration of seemingly endless studies of CSF biomarkers in AD appears online in an early publication from Neurology.

The best predictive model for the development of AD considered CSF levels of sAPPβ and tau, along with age—for a sensitivity and specificity in the 80% range. For the purposes of differentiation, the 2 CSF biomarkers provided a sensitivity of 95% and a specificity of, again, about 80%. Notably CSF levels of amyloid beta 1-42, which have been used previously by others (see here, for example), "did not contribute significantly to the models."

The authors caution that the "modest number of patients" in their study, 58, and the "relatively short follow-up period," an average of ~33 months, "may have resulted in an underestimation of the predictive value of sAPPβ" [emphasis added].

CSF = cerebrospinal fluid; MCI = mild cognitive impairment.

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