Cognitive training

The term brain fitness reflects a hypothesis that cognitive abilities can be maintained or improved by exercising the brain, in analogy to the way physical fitness is improved by exercising the body. Although there is strong evidence that aspects of brain structure remain plastic throughout life, and that high levels of mental activity are associated with reduced risks of age-related dementia, scientific support for the concept of "brain fitness" is limited. The term is virtually never used in the scientific literature, but is commonly used in the context of self-help books and commercial products.[1] It first came into play in the 1980s, and appeared in the titles of self-help books in 1989[2] and 1990.[3]

Overview

Brain fitness is the capacity of a person to meet the various cognitive demands of life. It is evident in an ability to assimilate information, comprehend relationships, and develop reasonable conclusions and plans. Brain fitness can be developed by formal education, being actively mentally engaged in life, continuing to learn, and exercises designed to challenge cognitive skills.[4] Healthy lifestyle habits including mental stimulation, physical exercise, good nutrition, stress management, and sleep can improve brain fitness.[5] On the other hand, chronic stress, anxiety, depression, aging, air pollution, decreasing estrogen, excess oxytocin, and prolonged cortisol can decrease brain fitness as well as general health.[6]

As of 2010, there was insufficient evidence to recommend any method of preventing age-related memory deficits or Alzheimers.[7]

Neurogenesis

Main article: Neurogenesis

Neurogenesis is the creation of new neurons. The more active a particular brain cell is, the more connections it develops with its neighboring neurons through a process called dendritic sprouting. A single neuron can have up to thirty thousand such connections, creating a dense web of interconnected activity throughout the brain. Each neuron can then be stimulated directly through experience (real or imagined) or indirectly through these connections from its neighbors, which saves the cell from cell death.

Physical exercise boosts the brain’s rate of neurogenesis throughout life, while mental exercise increases the rate at which those new brain cells survive and make functional connections into existing neural networks.[8][9] Both physical exercise and the challenge from mental exercise increase the secretion of nerve growth factor, which helps neurons grow and stay healthy.[10]

Role of neurotrophins

Brain fitness is purported to be positively influenced through mental and physical exercises that increase levels neurotrophins. Neurotrophins are a small class of proteins that are vital in neuronal development and function. In development, neurotrophins act to protect and warrant the survival of an adequate number of neurons. The survival of ample neurons is vital to ensure that they are match for target innervations. Neurotrophins also assist cell fate decisions, innervations patterns, the development of axons, dendrite pruning, etc. Neurotrophins are also important for regulating neural function and neuronal survival.[11] Neurons are affected most predominantly by neurotrophins; however, they are important for many parts of the body in addition to the nervous system. Neurotrophins are crucial for the survival of neurons in the peripheral nervous system (PNS) as well as neurons in the central nervous system (CNS).[12] The four most common neurotrophins are Nerve Growth Factor (NGF), Brain Derived Neurotrophic Factor (BDNF), Neurotrophic Factor-3 (NT-3), and Neurotrophic Factor-4/5 (NT-4/5). In order to understand how neurotrophins affects brain fitness, it is important to understand how they work.

Nerve growth factor (NGF) was the first neurotrophin to be discovered and is the most famous.[13] The effects of NGF are present in a multitude of tissues through human development as well as adulthood. NGF is associated with immunity, stress reaction, nerve maintenance and neurodegenerative diseases.[14] NGF is known have a predominant effect on the sympathetic ganglion cells and dorsal root ganglion cells with free nerve endings and the cholinergic neurons of the basal nucleus.[12] Sympathetic ganglion cells are masses of neuronal cell bodies in the sympathetic branch of the visceral (autonomic) nervous system. Dorsal root ganglion are masses of neuronal cell bodies in the posterior portion of the spinal cord where sensory information is processed. Cholinergic neurons are profuse in parts of the brainstem, the base of the forebrain, and the basal ganglia. They are thought to play a role in regulating the general level of activity of CNS neurons, especially during the different phases of wakefulness and sleep and also during learning.[12] Therefore, it can be purported that increased secretion of NGF can stimulate the sympathetic nervous system, the sensory portion of the spinal cord, parts of the brainstem, the base of the forebrain, and the basal ganglia. Perhaps the roles of these individual structures can be facilitated or preserved with increased NGF.

Secretion of brain derived neurotrophic factor (BDNF) is stimulated by cortical neurons, and is essential for permanence of striatal neurons in the brain. Both patients with Alzheimer's and with Huntington disease exhibit reduced levels of BDNF.[15] Striatal neurons are the nerve cells that make up the stratium. The stratium is an inclusive term for several structures of the midbrain. The stratium is the major point of entry for receiving input from most or all cortical areas and analyzing inhibitory outputs to the various parts of the midbrain.[12] Therefore, it may be deduced that secretion of BDNF can have an influence on many parts of the cerebral cortex and coincidentally the functions of the areas influenced.

Spiral ganglion neurons are particularly sensitive to neurotrophic factor-3 (NT-3).[12] The spiral ganglion neurons contain the cell bodies of the auditory primary afferent fibers. The central process of these cells collect at the base of the cochlea to form the cochlear division of the eight nerve [12] These afferent fibers carry auditory impulses toward the central nervous system. Therefore, it may be reasoned that healthy levels of NT-3 can preserve the function of these cells that are crucial for processing auditory information in the brain.

An article entitled "Neurotrophin 4/5 is a trophic factor for mammalian facial motor neurons" summarizes a study that was conducted on the researchers’ findings in 1993. The research suggests that NT-4/5 prevents injuries that cause death of facial motor neurons in neonatal rats. Additionally, there is functional receptor for NT-4/5 in facial motor neurons that can be serviceable thought embryonic development and even postnatal life. Thus, both NT-4/5and brain-derived neurotrophic factor (BDNF) may be physiological survival factors for facial motor neurons and may serve as restorative means for motor neuron disease.[16]

Activities presumed to promote brain fitness

Not all brain activity exercises the brain in the same way.

Practical effects

A significant issue in brain fitness work has been establishing that brain training exercises have impacts on brain function that exist outside the context of the training task.[22]

Other studies, however, have looked at changes in tests of everyday function that occur after brain-based training. In a review of these studies, the following significant effects were noted. Improvements on speed of processing training tests were related to improvements in the Timed Instrumental Activities of Daily Living test (TIADL). Evidence of ceiling effects were also noted, indicating that subjects who were further below normal at the beginning of training had the largest expected gains. Further, the effect sizes may be related to customizing the training difficulty to the performance level of the trainee. Subjects trained with one training strategy, the Useful Field of View test (UFOV), showed significant improvements in an on-the-road driving test designed to evaluate driver response during potential dangerous situations. Specifically, subjects trained with UFOV made fewer dangerous maneuvers after training.[23] In another study, the researchers have found that action video game experience is shown to improve trainees’ probabilistic inference. These results were established both in visual and auditory tasks, indicating generalization across modalities.[24] In a study performed with Air force flight cadets it has been shown that training addressing attention control processes yielded significant transfer of skills from the training environment to actual flight.[25]

Lately, brain training games have been actively marketed as a "magic bullet" for Alzheimer's and Dementia. While there are few studies showing effectiveness of brain training for older adults,[26][27][28] it has to be noted that many brain training games are purely commercial and have no scientific footing. To address growing public concerns with regard to aggressive online marketing of brain games to older population, a group of neuroscientists published a letter warning general public that there is a lack of research showing effectiveness of brain games in elderly.[29] Authors of this letter suggest that many popular computerized training programs are not very effective and some other interventions, such intense physical exercise, may have greater benefits. With regard to research studies supporting benefits of brain training games for older adults, there is a strong evidence that participants only gain in the trained task and that there is limited transfer of skills to the real life activities.[30][31]

Another recent market for Brain Training services is children who are not meeting academic expectations in school. Student's performance on standardized norm-reference tests of cognitive abilities (e.g., Woodcock-Johnson Test of Cognitive Ability - IV) serve as a guide to determine which cognitive processes are relative strengths and weaknesses. For a description of these processes see Cattell–Horn–Carroll theory. A pre-training test provides both data on proposed weaknesses in need of training and a baseline measurement to compare performance on post-training administrations of the test. The assumption is that identifying and training a weaker cognitive process will result in generalizable improvements to academic performance. Cognitive training takes an analogue form of the skill performed on the test, and predictably does improve performance on that discrete skill in post-test measures. There is currently no evidence that this improvement in these discrete, trained skills, generalizes to better performance on higher order, more complex intellectual or academic skills.[32][33]

Examples

Several commercial and academic programs have arisen to provide brain training services.

Neurobics

Neurobics are mental exercises, that claim to enhance the brain's performance.[34] These exercises are described by Lawrence Katz and Manning Rubin in their book Keep Your Brain Alive, however they are not scientifically proven.[34][35] The term neurobics was popularized by Lawrence Katz in 1999.[36] It is presumed that unusual sensory stimulation and activities like non-routine actions and thoughts, produce more of such chemicals of the neurobiology system of body that encourage growth of new dendrites and neurons in the brain. Routine actions become so automatic to the individual that most of actions are done largely unconsciously. Such automated or unconscious actions require less activity in the brain, and exercise it less. With the help of neurobics exercises, it is claimed that one can stimulate the brain.

See also

References

  1. ↑ Sandra Aamodt, Sam Wang (November 8, 2007). "Exercise on the brain". New York Times.
  2. ↑ Vernon Mark, Jeffrey P. Mark (1989). Brain Power: A Neurosurgeon's Complete Program to Maintain and Enhance Brain Fitness Throughout Your Life. Houghton Mifflin. ISBN 978-0-395-49861-3.
  3. ↑ M. Le Poncin-Lafitte, Monique Le Poncin, Michael Levine (1990). Brain Fitness. Fawcett Columbine. ISBN 978-0-449-90348-3.
  4. ↑ Scarmeas, N; Y Stern (2003). "Cognitive reserve and lifestyle". J Clin Exp Neuropsychol 25 (5): 625–33. doi:10.1076/jcen.25.5.625.14576. PMC 3024591. PMID 12815500.
  5. ↑ Kramer, AF; Erickson KI; Colcombe SJ (2006). "Exercise, cognition, and the aging brain". J Appl Physiol 101 (4): 1237–42. doi:10.1152/japplphysiol.00500.2006. PMID 16778001.
  6. ↑ Elder, GA; De Gasperi R; Gama Sosa MA (2006). "Research update: neurogenesis in adult brain and neuropsychiatric disorders". Mt Sinai J Med 73 (7): 931–40. PMID 17195878.
  7. ↑ Williams, JW (Apr 2010). "Preventing Alzheimer's disease and cognitive decline" (PDF). Evid Rep Technol Assess 193: 1–727. PMID 21500874.
  8. ↑ Ernst, C; Olson AK; Pinel JP; Lam RW; Christie BR (2006). "Antidepressant effects of exercise: evidence for an adult-neurogenesis hypothesis?". J Psychiatry Neurosci 31 (2): 84–92. PMC 1413959. PMID 16575423.
  9. ↑ Wolf, SA; Kronenberg G; Lehmann K; Blankenship A; Overall R; Staufenbiel M; Kempermann G (2006). "Cognitive and physical activity differently modulate disease progression in the amyloid precursor protein (APP)-23 model of Alzheimer's disease". Biol Psychiatry 60 (12): 1314–23. doi:10.1016/j.biopsych.2006.04.004. PMID 16806094.
  10. ↑ Chaturvedi, RK; Shukla S; Seth K; Agrawal AK (2006). "Nerve growth factor increases survival of dopaminergic graft, rescue nigral dopaminergic neurons and restores functional deficits in rat model of Parkinson's disease". Neurosci Lett 398 (1–2): 44–9. doi:10.1016/j.neulet.2005.12.042. PMID 16423459.
  11. ↑ Huang, E. J.; Reichardt, L. F. (2001). "Neurotrophins: Roles in neuronal development and function". Annual Review of Neuroscience 24: 677–736. doi:10.1146/annurev.neuro.24.1.677. PMC 2758233. PMID 11520916.
  12. 1 2 3 4 5 6 Nolte, J. (2009). The human brain: An introduction to its functional anatomy. (6th ed., pp. 608–612). Philadelphia: Mosby Elsevier
  13. ↑ Nolte, J. (2009). The human brain: An introduction to its functional anatomy. (6th ed., pp. 608-612). Philadelphia: Mosby Elsevier
  14. ↑ Navis, A. R. (2007). Nerve growth factor. Embryo Project Encyclopedia, Retrieved from http://embryo.asu.edu/view/embryo:123957
  15. ↑ (2011). BDNF brain-derived neurotrophic factor [ homo sapiens ]. Retrieved from National Institutes of Health website: http://www.ncbi.nlm.nih.gov/gene/627
  16. ↑ Botstein, D.; Cayouette, M. H.; Berkemeier, L. R.; Clatterbuck, R. E.; Price, D. L.; Rosenthal, A. (1993). "Neurotrophin 4/5 is a trophic factor for mammalian facial motor neuron". Proceedings of the National Academy of Sciences of the United States of America 91 (8): 3304–3308. Bibcode:1994PNAS...91.3304K. doi:10.1073/pnas.91.8.3304. PMID 8159743.
  17. ↑ Grafman J (1994) Alternative frameworks for the conceptualization ofprefrontal lobe functions. In: Handbook of neuropsychology (Boller F,Grafman J, eds), pp 187–202. Amsterdam: Elsevier.
  18. ↑ Russo-Neustadt AA, Beard RC, Huang YM, Cotman CW; Beard; Huang; Cotman (2000). "Physical activity and antidepressant treatment potentiate the expression of specific brain-derived neurotrophic factor transcripts in the rat hippocampus". Neuroscience 101 (2): 305–12. doi:10.1016/S0306-4522(00)00349-3. PMID 11074154.
  19. ↑ Wilson, Robert S.; et al. (July 3, 2013). "Life-span cognitive activity, neuropathologic burden, and cognitive aging (Abstract)". Neurology. Archived from the original on July 5, 2013. Explained by Koren, Marina (July 23, 2013). "Being a Lifelong Bookworm May Keep You Sharp in Old Age". Smithsonian. Archived from the original on July 5, 2013.
  20. ↑ Gazzaley, Adam; et al. (September 5, 2013). "Video game training enhances cognitive control in older adults" (PDF). Nature.
  21. ↑ Kesler, Shelli; et al. (May 6, 2013). "Cognitive Training for Improving Executive Function in Chemotherapy-Treated Breast Cancer Survivors". Clinical Breast Cancer.
  22. ↑ NY Times Op-Ed Exercise on the Brain. Sandra Aamodt and Sam Wang. Nov 8 2007.
  23. ↑ The Impact of Speed of Processing Training on Cognitive and Everyday Functions.
    Author: Karlene Ball, Jerri D. Edwards, and Lesley A. Ross
    Journal: Journals of Gerontology: SERIES B 2007, Vol. 62B (Special Issue I): 19-31
  24. ↑ Green, Shawn; Pouge A, Bavelier D, (September 2010). "Improved Probabilistic Inference as a General Learning Mechanism with Action Video Games". Current Biology 20 (17): 1573–1579. doi:10.1016/j.cub.2010.07.040. PMC 2956114. PMID 20833324.
  25. ↑ Gopher, D (1992). "Development of skill transfer based on computer games: Prospects and Issues". Proceedings of the 36th annual meeting of the Human Factors Society 2: 1284.
  26. ↑ Kueider, Alexandra (2010). "Computerized Cognitive Training with Older Adults: A Systematic Review". PLOS ONE 7: e40588. Bibcode:2012PLoSO...740588K. doi:10.1371/journal.pone.0040588.
  27. ↑ Papp, Kathryn; et al. (2009). "Immediate and delayed effects of cognitive interventions in healthy elderly: A review of current literature and future directions". The Journal of the Alzheimer's Associations 5: 50–60. doi:10.1016/j.jalz.2008.10.008.
  28. ↑ Lampit, Amit; Hallock H, Valenzuela M, (Nov 2014). "Computerized Cognitive Training in Cognitively Healthy Older Adults: A Systematic Review and Meta-Analysis of Effect Modifiers". PLOS Medicine 11: e1001756. doi:10.1371/journal.pmed.1001756. PMID 25405755.
  29. ↑ "A Consensus on the Brain Training Industry from the Scientific Community". 2014.
  30. ↑ Owen, Adrian; et al. (2010). "Putting brain training to the test". Nature 465: 775–8. Bibcode:2010Natur.465..775O. doi:10.1038/nature09042. PMC 2884087. PMID 20407435.
  31. ↑ Melby-Lervåg, Monica; Hulme, Charles (2013). "Is working memory training effective? A meta-analytic review". Developmental Psychology 49: 270–291. doi:10.1037/a0028228. PMID 22612437.
  32. ↑ Hulme, C.; Melby-Lervag, M. (2012). "Current evidence does not support the claims made for CogMed working memory training". Journal of Applied Research in Memory and Cognition 1: 197–200. doi:10.1016/j.jarmac.2012.06.006.
  33. ↑ Redick, T. S.; Shipstead, Z.; Harrison, T. L.; Hicks, K. L.; Fried, D. E.; Hambrick, D. Z.; Kane, M. J.; Engle, R. W. (2012). "No evidence of intelligence improvement after working memory training: A randomized, placebo-controlled study.". Journal of Experimental Psychology: General 142: 1–21. doi:10.1037/a0029082. PMID 22708717.
  34. 1 2 Abby Ellin (1999-10-03). "Can 'Neurobics' Do for the Brain What Aerobics Do for Lungs?". The New York Times. Retrieved 2008-11-18.
  35. ↑ "A Workout For Your Brain- Forget About Kickboxing: How About Neurobics?". CBS News. 1999-08-27. Retrieved 2008-11-18.
  36. ↑ Melinda Beck (2008-06-08). "'Neurobics' and Other Brain Boosters". The Wall Street Journal. Retrieved 2008-11-18.

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