Panax ginseng as an adjuvant treatment for Alzheimer's disease

Abstract

Longevity in medicine can be defined as a long life without mental or physical deficits. This can be prevented by Alzheimer's disease (AD). Current conventional AD treatments only alleviate the symptoms without reversing AD progression. Recent studies demonstrated that Panax ginseng extract improves AD symptoms in patients with AD, and the two main components of ginseng might contribute to AD amelioration. Ginsenosides show various AD-related neuroprotective effects. Gintonin is a newly identified ginseng constituent that contains lysophosphatidic acids and attenuates AD-related brain neuropathies. Ginsenosides decrease amyloid beta-protein (A beta) formation by inhibiting beta- and gamma-secretase activity or by activating the nonamyloidogenic pathway, inhibit acetylcholinesterase activity and A beta-induced neurotoxicity, and decrease A beta-induced production of reactive oxygen species and neuro-inflammatory reactions. Oral administration of ginsenosides increases the expression levels of enzymes involved in acetylcholine synthesis in the brain and alleviates A beta-induced cholinergic deficits in AD models. Similarly, gintonin inhibits A beta-induced neurotoxicity and activates the nonamyloidogenic pathway to reduce A beta formation and to increase acetylcholine and choline acetyltransferase expression in the brain through lysophosphatidic acid receptors. Oral administration of gintonin attenuates brain amyloid plaque deposits, boosting hippocampal cholinergic systems and neurogenesis, thereby ameliorating learning and memory impairments. It also improves cognitive functions in patients with AD. Ginsenosides and gintonin attenuate AD-related neuropathology through multiple routes. This review focuses research demonstrating that ginseng constituents could be a candidate as an adjuvant for AD treatment. However, clinical investigations including efficacy and tolerability analyses may be necessary for the clinical acceptance of ginseng components in combination with conventional AD drugs. (C) 2018 The Korean Society of Ginseng, Published by Elsevier Korea LLC.