The Effect of Non-invasive Brian Stimulation on Language Production in Healthy Older Adults

The Effect of Transcranial Direct-current Stimulation on Discourse Production in Healthy Older Adults

The use of non-invasive brain stimulation techniques like transcranial direct-current stimulation (tDCS) for rehabilitation of language is a growing field that needs further studies to determine how best it can be used to enhance treatment outcomes. It has been shown that tDCS can improve language performance in healthy and brain-injured individuals such as increased naming accuracy. However, at present, it is not known what effect tDCS has on higher-level language skills like discourse production (i.e. story telling, giving instructions) in healthy, older speakers. Therefore, the aim of this study is to investigate in healthy older adults, the effect of tDCS on discourse production as well as the ideal tDCS electrode placement for improving language at the discourse level. It is hypothesised that tDCS will result in greater language changes and improvements during discourse production compared to no stimulation.

Transcranial direct-current stimulation is a non-invasive brain stimulation method that can modify spontaneous cortical activity in targeted brain regions. Anodal tDCS delivered through a positively charged electrode has been found to increase cortical excitability in a targeted brain region. Application of tDCS has been found to improve language production in healthy and brain-injured speakers.

total number of utterances (complete sentences including a predicate and argument) in a language sample

HADS is a 14-item scale which assesses non-somatic anxiety and depression symptoms experienced in the past week. Scores range from 0 to 21 for each sub-scale with a score ≥8 proposed for the identification of caseness, for both depression and anxiety.

The EPAQ2 is a self completed questionnaire which collects information on a person's physical activity levels at home, work and recreation. Based on total activity hours in the last 12 months, the physical activity index categorises levels of physical activity into 'active', 'moderately inactive', 'moderately active' or 'active'.

The KAP is a short questionnaire that measures participation levels in various activities such as activities of daily living, social activities and work in the last 4 weeks. A score of 0 indicates no restriction in participation whereas scores from 1-11 indicate a restriction in participation in at least one activity ( the higher the score the greater the restriction).

Inclusion Criteria: At least 65 years of age Native English speakers Right handed Normal aided or unaided visual acuity At least secondary school level of education Exclusion Criteria: History of neurological disease or cognitive impairment Any contraindication of tDCS (i.e. history of seizures, metal implants)

All information collected will be kept confidential and stored anonymously on password protected computers used only by research staff who are part of the study. Data will be stored securely in accordance with the Data Protection Act (1998) and the General Data Protection Regulations (May 2018). Stored, anonymised data may be used for future medical and health-related studies. Anonymised data will be retained for 10 years.

Nitsche MA, Paulus W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J Physiol. 2000 Sep 15;527 Pt 3(Pt 3):633-9. doi: 10.1111/j.1469-7793.2000.t01-1-00633.x.

Thair H, Holloway AL, Newport R, Smith AD. Transcranial Direct Current Stimulation (tDCS): A Beginner's Guide for Design and Implementation. Front Neurosci. 2017 Nov 22;11:641. doi: 10.3389/fnins.2017.00641. eCollection 2017.

Cattaneo Z, Pisoni A, Papagno C. Transcranial direct current stimulation over Broca's region improves phonemic and semantic fluency in healthy individuals. Neuroscience. 2011 Jun 2;183:64-70. doi: 10.1016/j.neuroscience.2011.03.058. Epub 2011 Apr 6.

Saffran EM, Berndt RS, Schwartz MF. The quantitative analysis of agrammatic production: procedure and data. Brain Lang. 1989 Oct;37(3):440-79. doi: 10.1016/0093-934x(89)90030-8.

Monti A, Ferrucci R, Fumagalli M, Mameli F, Cogiamanian F, Ardolino G, Priori A. Transcranial direct current stimulation (tDCS) and language. J Neurol Neurosurg Psychiatry. 2013 Aug;84(8):832-42. doi: 10.1136/jnnp-2012-302825. Epub 2012 Nov 8.

Nicholas LE, Brookshire RH. A system for quantifying the informativeness and efficiency of the connected speech of adults with aphasia. J Speech Hear Res. 1993 Apr;36(2):338-50. doi: 10.1044/jshr.3602.338.

Wilkie R, Peat G, Thomas E, Hooper H, Croft PR. The Keele Assessment of Participation: a new instrument to measure participation restriction in population studies. Combined qualitative and quantitative examination of its psychometric properties. Qual Life Res. 2005 Oct;14(8):1889-99. doi: 10.1007/s11136-005-4325-2.

Zigmond AS, Snaith RP. The hospital anxiety and depression scale. Acta Psychiatr Scand. 1983 Jun;67(6):361-70. doi: 10.1111/j.1600-0447.1983.tb09716.x.

Wareham NJ, Jakes RW, Rennie KL, Mitchell J, Hennings S, Day NE. Validity and repeatability of the EPIC-Norfolk Physical Activity Questionnaire. Int J Epidemiol. 2002 Feb;31(1):168-74. doi: 10.1093/ije/31.1.168.