Cube copying test in combination with rCBF or CSF A beta 42 predicts development of Alzheimer's disease

The aim was to identify subjects with incipient Alzheimer's disease (AD) among patients with mild cognitive impairment (MCI) using brief cognitive tests.

A total of 147 MCI patients were followed for 4-6 years and the incidence of AD was 11.6%/year. At baseline, the cube copying test, clock drawing test, MMSE and measurements of regional cerebral blood flow (rCBF) and cerebrospinal fluid (CSF) beta-amyloid(1-42) (A beta (42)) were performed.

The cube copying test, but not the clock drawing test, could predict AD among MCI patients with an area under the receiver operating characteristic curve of 0.64 (p < 0.01). The relative risk for future AD was increased in MCI subjects with impaired cube copying test (sex- and age-adjusted hazard ratio = 1.8, p < 0.05) and the incidence of AD was 18.2% in this subgroup. Combining the cube copying test with either rCBF or CSF A beta(42) had additive effects on the risk assessment for future development of AD. MCI patients achieving high scores on both MMSE and cube copying test had a very low risk of developing AD (incidence of AD = 1.6%).

In conclusion, combinations of the cube copying test with MMSE, rCBF and CSF A beta (42) measurements can identify subgroups of MCI subjects with either substantially reduced or increased risk for future development of AD.