REM-SLEEP PARAMETERS IN THE DISCRIMINATION OF PROBABLE ALZHEIMERS-DISEASE FROM OLD-AGE DEPRESSION

Thirteen dementia of the Alzheimer type (DAT) patients and fifteen old -age major depressive disorder (OAD) patients were investigated by pol ysomnography. The sleep was recorded during two nights after a 1 week wash-out period of psychotropic drugs. No statistically significant di fferences between the two groups were found concerning sleep continuit y or architecture. The amount of REM sleep was significantly lower in DAT in comparison with OAD patients (11.7% verses 18.5%). Also, total REM density as well as the density of the first REM period were signif icantly lower in the DAT compared with the OAD patient group (15.8% ve rses 32.5%, 14.9% verses 38.1%, respectively). REM latency did not dif fer between both groups. Because REM latency is known from other studi es to be shortened in depressed patients due to a cholinergic hyperact ivity, the opposite finding, i.e., prolongation of REM latency, was ex pected for DAT patients. This assumption, however, could not be confir med in the present study. It is concluded that REM density may better differentiate between DAT and OAD.