Biomarkers in cerebrospinal fluid may indicate whether patients with mild cognitive impairment will progress to Alzheimer's disease and could assist in the development of new screening tools or treatments, according to Dr. Oskar Hansson of Lund University, Malmö, Sweden, and his associates.
The investigators followed 137 patients with mild cognitive impairment who had consulted the memory disorder clinic at the university hospital between July 1998 and June 2001. A control population of 39 healthy volunteers with no memory complaints, good cognitive functioning, and without neurologic or psychiatric disease was recruited from Malmö.
The researchers followed the populations for 4–6 years after scientists took cerebrospinal fluid from a lumbar puncture.
A total of 57 patients with mild cognitive impairment at baseline developed Alzheimer's disease during the study period, and 21 developed other forms of dementia. Those patients with abnormal concentrations of the biomarkers β-amyloid, total tau, and phosphorylated tau at the beginning of the study were more likely to have progressed to Alzheimer's disease (Lancet Neurol. 2006;5:228–34).
Concentrations of total tau greater than 350 ng/L and of β-amyloid less than 530 ng/L at baseline were defined as pathologic. Patients with pathologic levels of the biomarkers were more than 20 times as likely to progress to Alzheimer's disease as those with mild cognitive impairment but without the pathologic levels of biomarkers, reported the authors.
Earlier studies followed those biomarkers in patients for only 1–2 years. Because of this study's long follow-up, “the diagnosis of stable [mild clinical impairment] is more reliable in this study, compared with previous investigations,” the investigators said.