Lipoic acid as a novel treatment for Alzheimer's disease and related dementias

• Published in: Pharmacology & therapeutics (Oxford) 2007-01, Vol.113 (1), p.154-164
• Main Authors: Holmquist, Lina, Stuchbury, Grant, Berbaum, Katrin, Muscat, Sonja, Young, Simon, Hager, Klaus, Engel, Jürgen, Münch, Gerald
• Format: Article
• Language: English
• Subjects: Aged; Alzheimer Disease - drug therapy; Alzheimer Disease - metabolism; Alzheimer Disease - physiopathology; Anti-Inflammatory Agents - pharmacology; Anti-Inflammatory Agents - therapeutic use; Antioxidants - pharmacology; Antioxidants - therapeutic use; Cerebrovascular Circulation - drug effects; Chelating Agents - pharmacology; Choline O-Acetyltransferase - metabolism; Clinical Trials as Topic - methods; Female; Free Radical Scavengers - pharmacology; Glucose - metabolism; Glutathione - metabolism; Humans; Lipid Peroxidation - drug effects; Metals - metabolism; Neuroprotective Agents - pharmacology; Neuroprotective Agents - therapeutic use; Oxidative Stress - drug effects; Thioctic Acid - pharmacology; Thioctic Acid - therapeutic use; Treatment Outcome
• ISSN: 0163-7258
• DOI: 10.1016/j.pharmthera.2006.07.001

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that destroys patient memory and cognition, communication ability with the social environment and the ability to carry out daily activities. Despite extensive research into the pathogenesis of AD, a neuroprotective treatment - particularly for the early stages of disease - remains unavailable for clinical use. In this review, we advance the suggestion that lipoic acid (LA) may fulfil this therapeutic need. A naturally occurring precursor of an essential cofactor for mitochondrial enzymes, including pyruvate dehydrogenase (PDH) and alpha-ketoglutarate dehydrogenase (KGDH), LA has been shown to have a variety of properties which can interfere with pathogenic principles of AD. For example, LA increases acetylcholine (ACh) production by activation of choline acetyltransferase and increases glucose uptake, thus supplying more acetyl-CoA for the production of ACh. LA chelates redox-active transition metals, thus inhibiting the formation of hydroxyl radicals and also scavenges reactive oxygen species (ROS), thereby increasing the levels of reduced glutathione. Via the same mechanisms, downregulation redox-sensitive inflammatory processes is also achieved. Furthermore, LA can scavenge lipid peroxidation products such as hydroxynonenal and acrolein. The reduced form of LA, dihydrolipoic acid (DHLA), is the active compound responsible for most of these beneficial effects. R-alpha-LA can be applied instead of DHLA, as it is reduced by mitochondrial lipoamide dehydrogenase, a part of the PDH complex. In this review, the properties of LA are explored with particular emphasis on how this agent, particularly the R-alpha-enantiomer, may be effective to treat AD and related dementias.