Check out part one of this series.

Here comes your man - Dopamine

Dopamine directly influences the PFC by modulating the highly sensitive neurochemical environment.1 Catecholamines such as dopamine and noradrenaline, have long been established as major players in the prevention or development of fatigue.2 Dopamine is our ‘reward’ neurotransmitter and as such it has been hypothesised to influence states of mental fatigue due to a lack of perceived reward over prolonged periods of time.3 The longer you perform or repeat a task, the aspect of reward may become skewed and the perceived reward becomes less than the physical or mental output. In other words, the boredom outweighs the motivation.3,4

Nutrients such as tyrosine, zinc and iron have been shown to improve dopamine levels and modulate its activity, therefore improving concentration and mental output.5,6,7 Specifically, tyrosine supplementation has been reported to improve stress-induced behavioural and cognitive issues particularly involving memory and attention-focussed tasks.2 Interestingly, increasing BDNF can also assist in enhancing neuronal dopamine release and enhance neuron survival.8 Healthy lifestyle habits such as exercise,8 as well as incorporating various botanicals as mentioned above can help to support BDNF levels and assist cognitive performance.9,10

Minding your mitochondria

The regulation of synaptic plasticity, and production of neurotransmitter and neurotrophic factors that promote mental focus, learning and memory relies on neurons having sufficient ATP. 10 Therefore, mitochondrial health is critically important for optimal brain activity and reduced mitochondrial function is associated with mental fatigue. 11 Consequently, processes that impair energy metabolism, such as inflammation, ageing and oxidative stress will contribute to cognitive decline and fatigue.12 Supporting cellular energy synthesis with nutrients such as B vitamins, magnesium, acetyl-L-carnitine (ALCAR) and coenzyme Q10 (CoQ10) are beneficial to enhance mitochondrial function and subsequently mental energy.11,13,14

Adaptogenic herbs such as Rhodiola rosea (Rhodiola), Panax ginseng (Korean ginseng) and Schisandra chinensis (Schisandra) improve stress tolerance and reduce fatigue as well as promote significant benefits for cellular energy mechanisms and cognitive function:

• Rhodiola – normalises stress hormone release whilst simultaneously activating ATP synthesis in mitochondria to improve energy, and improves cognition.15
• Korean ginseng – stimulates Nrf2 to produce antioxidant, it protects cells from effects of metabolic oxidative processes, improves cognitive function, learning and memory, and is neuroprotective.16,17
• Schisandra – improves cognitive function in chronic stress, protects cells from oxidative stress, neuroprotective, regulates neurotransmitters, and modulates BDNF.10,18

Mind-hacking mental fatigue

The table below gives a quick reference guide to herbal and nutritional ingredients that enhance mental energy through various mechanisms.

Beyond supplementation, there are lifestyle strategies that can be used to promote neuroplasticity and regulate neurotransmitter production such as:

• Encourage adequate sleep cycles and rest – studies show that sufficient sleep is linked with increased BDNF levels and regulates cognitive performance.19
• Healthy nutritional intake –sufficient nutritional foundations are required for neurotransmitter production, mitochondrial function and neuronal regulatory mechanisms.
• Regular exercise increases plasticity,17 and supports neurotransmitter production.8
• Take regular mental breaks where possible. Consider breaking up cognitive tasks with brain gym techniques to assist in concentration, improve retention and reduce fatigue.20

Challenging daily mental fatigue

Our day-to-day lives require a steady stream of mental attention, from the time we wake up until when we go to sleep at night, so it’s little wonder that both physical and mental fatigue are so prevalent. Incorporating some of the above key supplementation strategies as well as identifying where individuals can make suitable lifestyle changes can often be the difference in clearing a cloudy mind and improving mental energy and focus.

References

1 - Cools R, Robbins TW. Chemistry of the adaptive mind. Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences. 2004 Dec 15;362(1825):2871-88.

2 - Meeusen R, Watson P, Dvorak J. The brain and fatigue: new opportunities for nutritional interventions? Journal of sports sciences. 2006 Jul 1;24(07):773-82.

3 - Boksem MA, Tops M. Mental fatigue: costs and benefits. Brain research reviews. 2008 Nov 1;59(1):125-39.

4 - Tran Y, Craig A, Craig R, Chai R, Nguyen H. The influence of mental fatigue on brain activity: Evidence from a systematic review with meta-analyses. Psychophysiology. 2020 May;57(5):e13554.

5 - Meltzer HY, Stahl SM. The dopamine hypothesis of schizophrenia: a review. Schizophrenia bulletin. 1976;2(1):19.

6 - Pifl C, Wolf A, Rebernik P, Reither H, Berger ML. Zinc regulates the dopamine transporter in a membrane potential and chloride dependent manner. Neuropharmacology. 2009 Feb 1;56(2):531-40.

7 - Unger EL, Bianco LE, Jones BC, Allen RP, Earley CJ. Low brain iron effects and reversibility on striatal dopamine dynamics. Experimental neurology. 2014 Nov 1;261:462-8.

8 - Foley TE, Fleshner M. Neuroplasticity of dopamine circuits after exercise: implications for central fatigue. Neuromolecular medicine. 2008 Jun 1;10(2):67-80.

9 – Sangiovanni E, Brivio P, Dell’Agli M, Calabrese F. Botanicals as modulators of neuroplasticity: focus on BDNF. Neural plasticity. 2017 Oct;2017.

10 - Jang Y, Lee JH, Lee MJ, Kim SJ, Ju X, Cui J et al. Schisandra extract and ascorbic acid synergistically enhance cognition in mice through modulation of mitochondrial respiration. Nutrients. 2020 Apr;12(4):897.

11 – Nicolson GL. Mitochondrial dysfunction and chronic disease: treatment with natural supplements. Integrative Medicine: A Clinician's Journal. 2014 Aug;13(4):35.

12 - Ishii A, Tanaka M, Watanabe Y. Neural mechanisms of mental fatigue. Reviews in the Neurosciences. 2014 Aug 1;25(4):469-79.

13 – Malaguarnera M, Gargante MP, Cristaldi E, Colonna V, Messano M, Koverech A, et al. Acetyl L-carnitine (ALC) treatment in elderly patients with fatigue. Archives of gerontology and geriatrics. 2008 Mar 1;46(2):181-90.

14 - Tomassini V, Pozzilli C, Onesti E, Pasqualetti P, Marinelli F, Pisani A, et al. Comparison of the effects of acetyl L-carnitine and amantadine for the treatment of fatigue in multiple sclerosis: results of a pilot, randomised, double-blind, crossover trial. Journal of the neurological sciences. 2004 Mar 15;218(1-2):103-8.

15 - Anghelescu IG, Edwards D, Seifritz E, Kasper S. Stress management and the role of Rhodiola rosea: a review. International journal of psychiatry in clinical practice. 2018 Oct 2;22(4):242-52.

16 - Cho IH. Effects of Panax ginseng in neurodegenerative diseases. Journal of ginseng research. 2012 Oct;36(4):342.

17 - Kim JH. Cardiovascular diseases and Panax ginseng: a review on molecular mechanisms and medical applications. Journal of ginseng research. 2012 Jan;36(1):16.

18 - Zhang M, Xu L, Yang H. Schisandra chinensis fructus and its active ingredients as promising resources for the treatment of neurological diseases. International journal of molecular sciences. 2018 Jul;19(7):1970.

19 - Fan TT, Chen WH, Shi L, Lin X, Tabarak S, Chen SJ, et al. Objective sleep duration is associated with cognitive deficits in primary insomnia: BDNF may play a role. Sleep. 2019 Jan;42(1):zsy192.

20 - Aulia FD, Setiadi AE, Rahayu HM. The Differences of Brain Based Learning and Somatic Auditory Visual and Intellectual Based on Brain Gym Toward Students' Learning Outcomes and Retention. JPI (Jurnal Pendidikan Indonesia). 2021 Mar 10;10(1).