Alzheimerʹs disease and eyeblink conditioning: 750 ms trace vs. 400 ms delay paradigm

Patients with probable Alzheimerʹs disease (AD) and hippocampal disruption are severely impaired in eyeblink classical conditioning (EBCC) in the 400 ms delay paradigm. Hippocampectomized rabbits are not impaired in the delay paradigm but perform poorly in the trace paradigm. It was anticipated that probable AD patients would be severely impaired in the 750 ms trace paradigm. In Study 1, probable AD patients were significantly impaired in the trace EBCC paradigm, but the sensitivity of the test was poorer than for the delay paradigm. In Study 2, probable AD patients tested in trace were tested in the delay paradigm 4 months later. Sensitivity for AD was also better for the delay paradigm. Rabbits and humans show behavioral parallels in the 400 ms delay paradigm but not in the 750 ms trace paradigm. The 400 ms delay EBCC paradigm was superior to the 750 ms trace paradigm for the detection of AD.