Transcranial Electrical Nerve Stimulation for Dementia

Overview[edit | edit source]

TDCS administration.gif

Transcranial electrical nerve stimulation (tES) or Cranial Electrical Nerve Stimulation, CES, is a non-invasive brain stimulation where brain activity is excited or inhibited by application of a low voltage constant or alternating currents to the human brain via scalp electrodes.[1]

Image 1: tES administration. A subject (front) sits on a sofa relaxed, and a researcher (behind) controls the tDCS device (a). A head strap (d) for convenience and reproducibility, and also use a rubber band (e) for reducing resistance

The tES is a promising tool in rehabilitation, based on the growing evidence that delivery of current to specific brain regions can promote desirable plastic changes[2]. The tES is becoming a topic for non-pharmacological management of various cognitive related conditions and this concept is still under research for effectiveness.[3]

  • The tES is one of the techniques used to stimulate the brain of a person with dementia.[4]
  • Recent evidence had shown that tES alone or in combination with physiotherapy improves certain functional activities in person with possible cognitive impairment[5]
  • The tES is not a common practice among physiotherapists who are one of the experts in dementia management. Accordingly, this paper will provide information on the tES method of application to stimulate the brain of a person with dementia.

Dementia (Major Neurocognitive disorder)[edit | edit source]

Dementia is an impairment in one or more cognitive domains with impaired functional status[6], which is of concern to both patient and patient relative. Neuropsychological and behavioural characteristics such as anxiety, depression and sleep disturbances are prominent features of dementia.[7][8] These symptoms, including neurocognitive dysfunction, may be enhanced by using transcranial electrical nerve stimulation.[4][9][10].

Mechanism of Transcranial electrical nerve stimulation[edit | edit source]

Non-Invasive brain stimulation (transcranial electrical nerve stimulation ) main modalities are of different type and in this write up direct and alternating current type of trans-cranial electrical nerve stimulation mechanism will be discussed.[11]

  • Transcranial alternating current stimulation, tACS, delivers an alternated sinusoidal current at a specific frequency. In tACS, specific sine-wave stimulation waveforms interact with endogenous brain oscillations to alter neuronal plasticity for desired outcome.[12]
  • Transcranial direct current stimulation, tDCS. The tDCS is believed to alter neuronal excitability by excitatory or inhibitory action and consequently modulating synaptic plasticity (long term potentiation or long term depression)[12].

Aside the direct and alternating current type of trans-cranial electrical nerve stimulation, It is important to highlight on some of the other existing forms of the non-invasive brain stimulation, which include:

  1. Transcranial magnetic stimulation (TMS) - an electromagnet placed on the scalp generates magnetic field pulses that can activate axons and cause them to fire action potentials. For repetitive transcranial magnetic stimulation, it uses repeated application of TMS pulses for modulating brain activity.
  2. Repetitive transcranial magnetic stimulation, rTMS.[13] - which uses repeated application of TMS pulses for modulating brain activity.

Cognitive Impairment Assessment[edit | edit source]

Evaluating a person with dementia requires neuropsychological assessment tools. Among these tools, the most common universally used is Mini Mental State Examination(MMSE)[14] and for functional status, Functional Activities Questionnaire (FAQ) for older adults might be used[15]. And these assessment tools, the MMSE and FAQ can as well used tools to monitor the progress of the intervention of a person with major neurocognitive impairment.

TES in Physiotherapy Practice for Brain Stimulation[edit | edit source]

Promising findings suggest that tDCS may be a useful standalone treatment or a helpful complement to other physiotherapy treatments in managing chronic pain and neurological conditions.


  • There are only a small number of heterogeneous studies.
  • There is a need of further studies that will contribute to the current studies evidence in terms of tDCS parameters, long-term follow-up and different pathological populations. This will aid in determining tDCS clinical efficacy.
  • It is of importance to note that while there are evidences pointing to potential benefits of tDCS for dementia population it's clinical application in physiotherapy practice still needs to be extensively studied.[16]

tDCS in stroke rehabilitation:

  • In a randomised controlled trial conducted by Pires and colleagues, it was concluded that five tDCS sessions are sufficient to augment the effect of standard physiotherapy on upper limb function recovery in chronic post-stroke patients, and ten sessions resulted in greater gains [17].
  • In the study conducted by Garrido and colleagues, they concluded that combining modified CIMT with bihemispheric tDCS in patients hospitalised with acute to subacute stroke allows us to maximise the motor and functional recovery of the paretic upper limb in the early stages and independence in ADL, maintaining the effects over time [18].
  • In chronic stroke patients with severe hemiparesis of the upper limb, it was found that combined tDCS and virtual reality-based paradigm provided not only greater but also clinically meaningful improvement in the motor function (and similar sensory effects) in comparison to conventional physical therapy [19].
  • Current findings suggest that tDCS combined with Robotic Therapy (RT) does not improve upper limb function, strength, spasticity, functional independence or velocity of movement after stroke [20]. However, tDCS may enhance the effects of RT alone for lower limb function. tDCS parameters and the stage or type of stroke injury could be crucial factors that determine the effectiveness of this therapy.

References[edit | edit source]

  1. Bestmann S, Walsh V. Transcranial electrical stimulation. Curr Biol. 2017 Dec 4;27(23):R1258-R1262.
  2. Truong D, Minhas P, Nair A, Bikson M. Computational modeling assisted design of optimized and individualized transcranial direct current stimulation protocols. InThe stimulated brain 2014 Jan 1 (pp. 85-115). Academic Press.Available: 23.9.2021)
  3. Reed T, Kadosh RC. Transcranial electrical stimulation (tES) mechanisms and its effects on cortical excitability and connectivity. Journal of inherited metabolic disease. 2018 Nov 2;41(6):1123-30.
  4. 4.0 4.1 Cameron MH, Lonergan E, Lee H. Transcutaneous electrical nerve stimulation (TENS) for dementia. Cochrane Database of Systematic Reviews. 2003(3).
  5. Yotnuengnit P, Bhidayasiri R, Donkhan R, Chaluaysrimuang J, Piravej K. Effects of transcranial direct current stimulation plus physical therapy on gait in patients with Parkinson disease: a randomized controlled trial. American journal of physical medicine & rehabilitation. 2018 Jan 1;97(1):7-15.
  6. American Psychiatric Association. Diagnostic and statistical manual of mental disorders (DSM-5®). American Psychiatric Pub; 2013 May 22.
  7. Burke AD, Goldfarb D, Bollam P, Khokher S. Diagnosing and Treating Depression in Patients with Alzheimer’s Disease. Neurology and therapy. 2019 Aug 1:1-26.
  8. Müller-Spahn F. Behavioral disturbances in dementia. Dialogues in clinical neuroscience. 2003 Mar;5(1):49.
  9. Das N, Spence JS, Aslan S, Vanneste S, Mudar R, Rackley A, Quiceno M, Chapman SB. Cognitive training and transcranial direct current stimulation in mild cognitive impairment: A randomized pilot trial. Frontiers in Neuroscience. 2019;13:307.
  10. Moreno-Duarte I, Gebodh N, Schestatsky P, Guleyupoglu B, Reato D, Bikson M, Fregni F. Transcranial electrical stimulation: transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial pulsed current stimulation (tPCS), and transcranial random noise stimulation (tRNS). InThe stimulated brain 2014 Jan 1 (pp. 35-59). Academic Press.
  11. Yavari F, Jamil A, Samani MM, Vidor LP, Nitsche MA. Basic and functional effects of transcranial electrical stimulation (tES)—an introduction. Neuroscience & Biobehavioral Reviews. 2018 Feb 1;85:81-92.
  12. 12.0 12.1 Elyamany O, Leicht G, Herrmann CS, Mulert C. Transcranial alternating current stimulation (tACS): from basic mechanisms towards first applications in psychiatry. European Archives of Psychiatry and Clinical Neuroscience. 2020 Nov 19:1-22.
  13. Fertonani A, Miniussi C. Transcranial electrical stimulation: what we know and do not know about mechanisms. The Neuroscientist. 2017 Apr;23(2):109-23.
  14. Folstein MF, Folstein SE, McHugh PR. “Mini-mental state”: a practical method for grading the cognitive state of patients for the clinician. Journal of psychiatric research. 1975 Nov 1;12(3):189-98.
  15. Mayo AM. Use of the Functional Activities Questionnaire in older adults with dementia. Try This: Best Practices in Nursing Care to Older Adults with Dementia D. 2012;13.
  16. Schabrun SM. Transcranial direct current stimulation: a place in the future of physiotherapy?. Physical Therapy Reviews. 2010 Aug 1;15(4):320-6.
  17. Pires R, Baltar A, Sanchez MP, Antonino GB, Brito R, Berenguer-Rocha M, Monte-Silva K. Do Higher Transcranial Direct Current Stimulation Doses Lead to Greater Gains in Upper Limb Motor Function in Post-Stroke Patients?. International Journal of Environmental Research and Public Health. 2023 Jan;20(2):1279.
  18. Garrido M, Álvarez E, Acevedo F, Moyano Á, Castillo N, Ch GC. Early transcranial direct current stimulation with modified constraint-induced movement therapy for motor and functional upper limb recovery in hospitalized patients with stroke: A randomized, multicentre, double-blind, clinical trial. Brain Stimulation. 2023 Jan 1;16(1):40-7.
  19. Llorens R, Fuentes MA, Borrego A, Latorre J, Alcañiz M, Colomer C, Noé E. Effectiveness of a combined transcranial direct current stimulation and virtual reality-based intervention on upper limb function in chronic individuals post-stroke with persistent severe hemiparesis: a randomized controlled trial. Journal of NeuroEngineering and Rehabilitation. 2021 Dec;18:1-3.
  20. Comino-Suárez N, Moreno JC, Gómez-Soriano J, Megía-García Á, Serrano-Muñoz D, Taylor J, Alcobendas-Maestro M, Gil-Agudo Á, Del-Ama AJ, Avendaño-Coy J. Transcranial direct current stimulation combined with robotic therapy for upper and lower limb function after stroke: a systematic review and meta-analysis of randomized control trials. Journal of NeuroEngineering and Rehabilitation. 2021 Dec;18(1):1-6.