Cognitive effects of scopolamine in dementia

Cholinergic deficiency was postulated to play an important role in the mental decline observed in Alzheimer's (AD), Parkinson's (PD) and multiinfarct (MID) dementia. In the present study, 11 AD, 8 MID and 7 PD patients (DSM III-R diagnostic criteria for dementia) and 9 healthy age-matched controls (CTRL) were given IV 0.5 mg scopolamine (SCO) or placebo (PLA) in random order (double blind) within one week. The Hebrew Short Mental Test (SMT) and Wechsler Memory Scale (WMS) were administered before and after SCO and PLA in each patient. A comparison of SCO vs. PLA utilizing MANCOVA (the covariate being the basal mental performance [BAS] with SMT or WMS) showed that SCO affected all the groups similarly, except for the Wechsler subtest of logic memory which showed larger deterioration in CTRL compared to demented patients. ANOVA and MANCOVA analyses did not distinguish between the three demented groups. SCO administration does not differentiate between demented patients and CTRL and does not enable discrimination between patients with AD, MID and PD. Moreover, some CTRL with still normal cognitive performance, but lower BAS may be more vulnerable to SCO than others. The integrity of the cholinergic system may be responsible for the different sensitivity to SCO challenge.