Ashwagandha (Withania somnifera), also known as Indian ginseng or Winter cherry, is one of the most important herbs in Ayurvedic medicine. It has been used for millennia as a rejuvenating tonic, i.e. to increase physical and mental health by promoting longevity. Classically, different parts of the plant (including roots, leaves and flowers) have been used to treat different conditions such as rheumatism, constipation, insomnia, chronic stress and hormonal imbalances.

Recently, the benefits of this herb have aroused the interest of conventional western medicine and in the last 10 years many studies have been published bringing scientific evidence for what the ancients used to practice many years ago.

Although studies in humans are still limited, both in vitro and animal model research shows evidence of Ashwagandha’s effect on the treatment of diabetes, cancer, stress, anxiety, schizophrenia, male infertility, neurodegenerative diseases, as well as on muscle mass gain and athlete performance.

Most of Ashwagandha’s effects are attributed to its ability to regulate hormone secretion and to adapt the body to stress. It is, therefore, considered a strong adaptogen. Its main action is to balance cortisol, a hormone secreted by the adrenal gland in situations of prolonged stress. However, other effects have already been reported, including anti-inflammatory and antioxidant effects.

Ashwagandha also reduces the level of amyloid beta (Aβ) deposits in brain cells and promotes regeneration of the axon (part of the nerve cell involved in nerve impulse transmission). Such effects show a possible role for this herb in the treatment of Alzheimer’s disease. In animal models we indeed can observe reversal of neuronal atrophy and recovery of synaptic function after treatment. Prevention of memory loss and improvement of dementia symptoms have also been reported.

Human studies are still rare, but there are reports of improved executive function, attention and information processing speed in patients with mild cognitive impairment – ICM (1) and bipolar disorder (2), in randomized clinical trials.

Ashwaganda’s mechanism of action in the treatment of Alzheimer’s disease was recently elucidated in an animal model study (3): rats with scopolamine-induced memory loss (a model widely used in studies for Alzheimer’s disease) showed recovery of symptoms after being fed with concentrated extract of W. somnifera leaf. In this study, the effects of Ashwagandha both in neuroprotection (nerve cell protection against lesion) and neurotrophism  (neuronal growth and regeneration) were well documented.

It was also demonstrated (4) that Ashwagandha’s effect on brain cortex functions occurs due to stimulation of acetylcholine receptors (M1 muscarinic receptors). Acetylcholine is an important neurotransmitter, acting as a promoter of the communication between neurons (synapse).  Stimulation of M1 receptors can mimic the effect of acetylcholine, improving nerve impulse transmission and reducing the symptoms of the disease.

The importance of acetylcholine in the physiopathology of Azheimer’s disease is so well established that one of the most common drugs for AD acts precisely by increasing the availability of this neurotransmitter in the brain. This group of drugs are called “cholinesterase inhibitors” (learn more at our section about  treatment).

Future clinical trials will bring more clarity about the effects of Ashwagandha on Alzheimer’s disease. Meanwhile, we count with the millenial use of Ashwagandha by tradicional systems of medicine being gradually confirmed by scientific studies of modern medicine.

Conclusion:

Ashwagandha is a potent adaptogen, traditionally used in Ayurvedic medicine. Its effects on memory, cognition and longevity are well known. Current scientific studies have elucidated its mechanism of action proving its effectiveness and turning this ancient herb into a promising weapon for the prevention and treatment of Alzheimer’s disease.

References

  1. Choudhary D, Bhattacharyya S, Bose S. Efficacy and Safety of Ashwagandha (Withania somnifera (L.) Dunal) Root Extract in Improving Memory and Cognitive Functions. J Diet Suppl. 2017 Nov 2;14(6):599-612.
  2. Singh N, Bhalla M, de Jager P, Gilca M. An overview on ashwagandha: a Rasayana (rejuvenator) of Ayurveda. Afr J Tradit Complement Altern Med. 2011;8(5 Suppl):208-213. doi:10.4314/ajtcam.v8i5S.9
  3. Konar A, Shah N, Singh R, Saxena N, Kaul SC, Wadhwa R, Thakur MK. Protective role of Ashwagandha leaf extract and its component withanone on scopolamine-induced changes in the brain and brain-derived cells. PLoS One. 2011;6(11):e27265.
  4. Konar A, Gupta R, Shukla RK, Maloney B, Khanna VK, Wadhwa R, Lahiri DK, Thakur MK. M1 muscarinic receptor is a key target of neuroprotection, neuroregeneration and memory recovery by i-Extract from Withania somnifera. Sci Rep. 2019 Sep 30;9(1):13990.
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