Therapy for Alzheimer's disease. Symptomatic or neuroprotective?

Therapeutic strategies aimed to treat Alzheimer's disease (AD) may either produce an attenuation of symptoms or slowdown deterioration by attenuating progression of the disease. Presently, cholinesterase inhibitors (ChEI) have shown the most promising therapeutic effects. The best documented clinical efficacy of ChEI are studies of THA (tacrine, tetrahydroaminoacridine). The results of five recent studies in a total of 1,242 patients are discussed. Based on differences from placebo in scoring, a gain of 2-12 (MMSE) or 5-6 (ADAS) in deterioration can be seen for a THA treatment of 2-3 mo duration. This suggests that if treatment with THA will be extended to a longer period, the drug effect may not be only a symptomatic improvement but also a slowdown of disease course. A similarity of THA's effect in AD with L-deprenyl effects in Parkinson's is suggested.