Spatial Discrimination and Passive Avoidance Behavior in The Rat: Age-Related Changes and Modulation by Chronic Dietary Choline Enrichment

Abstract

Because the number of elderly suffering from Alzheimer’s disease is increasing (Coyle et al., 1983), the problem of an age-associated decrease of memory has gained growing attention. Although different causes have been postulated for the memory impairments, the ‘cholinergic hypothesis of geriatric memory’ (Bartus et al., 1982) has received the most convincing support. This hypothesis states that central cholinergic dysfunction is the major cause of memory impairment. Consequently, there have been attempts to modulate cholinergic activity pharmacologically. One approach, characterized as precursor therapy (Bartus et al., 1984), tries to improve memory by enhancing the availability of the acetylcholine precursor choline (or lecithin). The rationale of this approach is twofold. Firstly, cholinergic activity can be increased by enhanced precursor availability (e.g. Haubrich et al., 1975). Hence, increased precursor availability is able to compensate for cholinergic dysfunctioning. Secondly, enhancement of cholinergic activity should be accompanied by a reduction of cognitive impairment (Bartus et al., 1984).