CSF biomarkers support AD diagnosis in nearly 90% of clinical cases

SAN DIEGO — Cerebrospinal fluid biomarkers supported the clinical diagnosis of Alzheimer’s disease in a small cohort of patients, per a poster presentation at the Alzheimer’s Association International Conference.

“We analyzed the use of biomarkers in our clinical setting ... [to check] the accuracy in which these biomarkers serve as a diagnostic tool in the clinical setting of a normal patient with suspected Alzheimer’s disease,” Pablo Agüero, MD, of Jiménez Díaz Foundation University Hospital in Madrid, said.

Agüero and colleagues analyzed 141 consecutive CSF samples of patients with suspected cognitive decline who were referred to the hospital’s memory clinic and utilized the Lumipulse G600II chemiluminescent immunoassay (Fujirebio) to determine the ratio of beta-amyloid 42, the 42/40 ratio, total Tau and phospho-Tau.

Researchers divided clinical diagnoses into AD, degenerative non-AD and non-degenerative, given clinical criteria at patients’ previous visits. They then separated the groups based on biomarkers: negative for AD (A–T–N– and A–T–N+), positive for AD (A+T+N+ and A+T+N–), cases with amyloidosis A+ but T– (A+T–N+; A+T–N–) and cases without amyloidosis A– but T+ (A–T+N+).

According to results, 50% of patients showed a positive AD result, which coincided with clinical amnestic AD phenotype or other related phenotypes, while 37% had a negative AD result that correlated to either non-AD neurodegenerative or non-degenerative diagnoses.

However, researchers found 13% of cases had inconsistencies within biomarkers, particularly with A– (n = 7) and A+ (n = 11) results. With respect to clinical diagnoses, all patients with A–T+N+ and eight of 11 patients with A+ biomarkers were considered AD phenotypes. In two cases of the former, AD diagnoses were later confirmed through positive PET-amyloid study and full positive CSF biomarkers.

“These biomarkers are a really useful diagnostic tool,” Agüero said. “In most cases, almost 90%, they give a very clear answer if the patient has [or doesn’t have] Alzheimer’s disease due to cognitive decline. And in those cases, in which the results are not clear, they tend to be Alzheimer’s disease.”