Guarana (Paullinia cupana Kunth): Applications to Alzheimer's disease and dementias

Alzheimer's disease (AD) is the most common form of dementia and consists of a progressive debilitating brain disorder that extensively affects the elderly, but remains incurable. Guarana is a highly caffeinated Amazonian plant largely used in dietary supplements and energy drinks, and studies have been demonstrating a wide range of beneficial effects on neurological disorders. Guarana prevents Aβ aggregation and toxicity, inhibits acetylcholinesterase and ameliorates memory and cognitive impairments, delays the aging process, protects against the development of metabolic disorders and the associated inflammation involved in the onset of brain disorders, and modulates neurotransmission related to anxiety, panic, and depression. Caffeine consumption is associated with reduced risk for dementia, but guarana has other bioactive compounds that work synergically for its multiple pharmacological effects. Considering that most investigations were conducted in vitro and in laboratory animals, more clinical investigations are needed to confirm the positive results of guarana in patients.