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Effectiveness of simultaneous dual-site transcranial direct current stimulation combined with integrated phonological and fine motor intervention compared with single interventions and sham in improving reading and phonological processing in 9-year-old boys with developmental dyslexia: a randomized, double-blind, sham-controlled trial

Protocol summary

Study aim
To evaluate the effectiveness of simultaneous dual-site transcranial direct current stimulation (tDCS) combined with integrated phonological and fine motor intervention, versus single interventions and sham, on reading and phonological processing in 9-year-old boys with developmental dyslexia.
Design
Randomized, double-blind, sham-controlled, 8-group component trial. Sample size: 160 (20 per group). Block randomization with block size 8 using a web-based sequence. Four assessment points: baseline, post-test, 3-month follow-up, 6-month follow-up.
Settings and conduct
Will be conducted in learning disorder clinics in Isfahan, Iran. Participants, parents, outcome assessors, therapists, and data analysts will be blinded; the tDCS operator will be unblinded. Topical benzocaine 6% will be applied before electrode placement to improve blinding.
Participants/Inclusion and exclusion criteria
Inclusion: 9-year-old boys with developmental dyslexia; NAMA T-score ≤30; Full Scale IQ ≥85; SCAS score <88; BOT-2 standard score ≤40; normal or corrected sensory function; no tDCS contraindications; written consent and verbal assent. Exclusion: intellectual disability; epilepsy; metal implants; scalp lesions; uncorrected sensory deficits; other major psychiatric or neurodevelopmental disorders requiring ongoing treatment.
Intervention groups
Eight groups: control plus sham; sham with phonological training; sham with non-targeted motor training; sham with combined intervention; active tDCS reading network plus phonological; active tDCS motor cortex plus motor; active dual-site tDCS plus combined; active tDCS motor cortex alone. tDCS: 1 mA, 20 min, 20 sessions.
Main outcome variables
Primary: change in composite NAMA Factor 1 score (word reading, phoneme deletion, nonword reading, word comprehension). Secondary: BOT-2 fine motor performance, rapid automatized naming, and text reading fluency.

General information

Reason for update
Acronym
IRCT registration information
IRCT registration number: IRCT20260817070696N1
Registration date: 2026-08-20, 1405/05/29
Registration timing: prospective

Last update: 2026-08-20, 1405/05/29
Update count: 0
Registration date
2026-08-20, 1405/05/29
Registrant information
Name
Mohammad Amin Javedanfar
Name of organization / entity
Shahid Beheshti University
Country
Iran (Islamic Republic of)
Phone
+98 21 2990 2761
Email address
m_javedanfar@sbu.ac.ir
Recruitment status
recruiting
Funding source
Expected recruitment start date
2026-08-23, 1405/06/01
Expected recruitment end date
2027-02-18, 1405/11/29
Actual recruitment start date
empty
Actual recruitment end date
empty
Trial completion date
empty
Scientific title
Effectiveness of simultaneous dual-site transcranial direct current stimulation combined with integrated phonological and fine motor intervention compared with single interventions and sham in improving reading and phonological processing in 9-year-old boys with developmental dyslexia: a randomized, double-blind, sham-controlled trial
Public title
Brain stimulation with combined reading and motor training for children with dyslexia
Purpose
Treatment
Inclusion/Exclusion criteria
Inclusion criteria:
Male children aged 9 years (9 years 0 months to 9 years 11 months) with developmental dyslexia diagnosed according to DSM-5 criteria by a clinical team. Reading and Dyslexia Test (NAMA) T score ≤ 30 (at least 2 standard deviations below the mean). Full Scale IQ ≥ 85 on the Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V). Score below 88 on the Spence Children's Anxiety Scale (SCAS). Fine motor deficits defined as standard score ≤ 40 on Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOT-2) manual dexterity and upper-limb coordination subtests. Normal or corrected-to-normal vision and hearing. No history of seizure or epilepsy, no scalp skin disease, no cochlear implant, cardiac pacemaker, or metal implants in the skull. Written informed consent from parents or legal guardian and verbal assent from the child.
Exclusion criteria:
Intellectual disability (Full Scale IQ < 85). Personal history of epilepsy or seizure disorder, or epilepsy in a first-degree relative. Presence of cochlear implant, cardiac pacemaker, or metal implants in the skull. Skin diseases or open lesions on the scalp at electrode sites. Uncorrected visual or hearing impairments. Other primary psychiatric or neurodevelopmental disorders requiring ongoing treatment (e.g., ADHD, autism spectrum disorder, severe anxiety disorder).
Age
From 108 months old to 119 months old
Gender
Male
Phase
N/A
Groups that have been masked
  • Participant
  • Care provider
  • Investigator
  • Outcome assessor
  • Data analyser
Sample size
Target sample size: 160
Randomization (investigator's opinion)
Randomized
Randomization description
Randomization will be performed using block randomization with a block size of 8. The unit of randomization will be the individual participant. A web-based random sequence generator (www.randomlists.com) will be used to create the allocation sequence. No stratification factors will be applied. Allocation concealment will be ensured by placing the allocation sequence in sequentially numbered, sealed, opaque envelopes. An independent research assistant who will not be involved in outcome assessment or intervention delivery will open the envelope at the time of each participant's enrollment and will assign the participant to the corresponding group.
Blinding (investigator's opinion)
Double blinded
Blinding description
Participants and their parents will be blinded to whether they receive active or sham tDCS. Outcome assessors and therapists delivering cognitive interventions will also be blinded. The tDCS operator will be the only unblinded person and will have no role in outcome assessment or cognitive training. Data analysts will be blinded to group labels until the primary analyses are completed. To reduce the initial tingling sensation and improve blinding, a topical local anesthetic (6% benzocaine) will be applied before electrode placement. A Data Safety and Monitoring Board (DSMB) will be unblinded as needed for safety monitoring.
Placebo
Used
Assignment
Parallel
Other design features
This will be an 8-group, theory-driven component trial (not a complete factorial design). The tDCS montage will be yoked to the type of cognitive intervention: TPJ stimulation for phonological training, M1 stimulation for motor training, and dual-site stimulation for the combined intervention. The combined intervention group will receive simultaneous two-channel tDCS and online cognitive training. A tDCS-only group (M1 montage) will be included to isolate the effect of motor cortex stimulation. Four assessment time points will be used: baseline, post-test, 3-month follow-up, and 6-month follow-up.

Secondary Ids

empty

Ethics committees

1

Ethics committee
Name of ethics committee
Research Ethics Committees of Shahid Beheshti University
Street address
Shahid Beheshti University, Shahid Shahriari Square, Evin, Tehran, Iran
City
Tehran
Province
Tehran
Postal code
1983969411
Approval date
2024-07-06, 1403/04/16
Ethics committee reference number
IR.SBU.REC.1403.103

Health conditions studied

1

Description of health condition studied
Developmental dyslexia
ICD-10 code
F81.0
ICD-10 code description
Specific reading disorder

Primary outcomes

1

Description
Composite score of Factor 1 of the Reading and Dyslexia Test, which includes word reading, phoneme deletion, nonword reading, and word comprehension subtests.
Timepoint
Before intervention, immediately after the end of intervention, 3 months after intervention, and 6 months after intervention.
Method of measurement
Reading and Dyslexia Test (a standardized Persian test for reading and dyslexia). The composite score of Factor 1 is calculated from the word reading, phoneme deletion, nonword reading, and word comprehension subtests.

Secondary outcomes

1

Description
Fine motor performance as measured by the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition, manual dexterity and upper-limb coordination subtests.
Timepoint
Before intervention, immediately after the end of intervention, 3 months after intervention, and 6 months after intervention.
Method of measurement
Bruininks-Oseretsky Test of Motor Proficiency, Second Edition. Raw scores of the common items in the manual dexterity and upper-limb coordination subtests will be used for longitudinal comparison.

2

Description
Rapid automatized naming speed, including naming of objects, colors, numbers, and letters.
Timepoint
Before intervention, immediately after the end of intervention, 3 months after intervention, and 6 months after intervention.
Method of measurement
Rapid Automatized Naming Test. The total time in seconds to name each card is recorded for the four subtests: objects, colors, numbers, and letters.

3

Description
Text reading fluency defined as the number of correct words read per minute on a grade-level reading passage.
Timepoint
Before intervention, immediately after the end of intervention, 3 months after intervention, and 6 months after intervention.
Method of measurement
Reading aloud a 100-word passage selected from the third-grade Persian textbook. Correct words per minute will be calculated as the total number of words minus errors, multiplied by 60, divided by the total reading time in seconds.

Intervention groups

1

Description
Control group: Participants will receive usual school education plus sham transcranial direct current stimulation. The sham stimulation will use the same electrode positions as the active groups, but the current will be applied for only 30 seconds and then gradually ramped down. For the control group, the sham montage will be randomly selected from the three main montages and will remain fixed across all 20 sessions. Sessions will be conducted three times per week for approximately seven weeks.
Category
Placebo

2

Description
Intervention group 1: sham transcranial direct current stimulation with the anode over the left temporoparietal junction and the cathode over the right temporoparietal junction, plus phonological awareness training. Sham stimulation will be applied for only 30 seconds. Phonological awareness training will be delivered in 20 sessions of 60 minutes each, three times per week for about 7 weeks, and will cover syllable segmentation, rhyme, phoneme blending and segmentation, initial and final phoneme identification, phoneme manipulation, and grapheme-to-phoneme mapping.
Category
Behavior

3

Description
Intervention group 2: sham transcranial direct current stimulation with the anode over the left primary motor cortex and the cathode over the right supraorbital region, plus non-targeted fine motor training. Sham stimulation will be applied for only 30 seconds. Non-targeted fine motor training will include activities without linguistic content, such as free play with dough, bead threading, pegboard tasks, and other manual dexterity exercises, delivered in 20 sessions of 60 minutes each, three times per week for about 7 weeks.
Category
Behavior

4

Description
Intervention group 3: sham transcranial direct current stimulation with a two-channel montage, including one channel over the temporoparietal junction and one channel over the left primary motor cortex, plus the integrated phonological and fine motor intervention. Sham stimulation will be applied for only 30 seconds on both channels. The integrated intervention will combine phonological awareness training with targeted fine motor activities linked to reading, such as forming letters with dough and stringing beads marked with phonemes, delivered in 20 sessions of 60 minutes each, three times per week for about 7 weeks.
Category
Behavior

5

Description
Intervention group 4: active transcranial direct current stimulation with the anode over the left temporoparietal junction and the cathode over the right temporoparietal junction, plus phonological awareness training. Active stimulation will be delivered at 1 milliampere for 20 minutes during the first part of each session, three times per week for 20 sessions over about 7 weeks. Phonological awareness training will be the same as Intervention group 1.
Category
Treatment - Devices

6

Description
Intervention group 5: active transcranial direct current stimulation with the anode over the left primary motor cortex and the cathode over the right supraorbital region, plus non-targeted fine motor training. Active stimulation will be delivered at 1 milliampere for 20 minutes during the first part of each session, three times per week for 20 sessions over about 7 weeks. Non-targeted fine motor training will be the same as Intervention group 2.
Category
Treatment - Devices

7

Description
Intervention group 6: active dual-site transcranial direct current stimulation with a two-channel montage, including one channel over the temporoparietal junction and one channel over the left primary motor cortex, plus the integrated phonological and fine motor intervention. Each channel will deliver 1 milliampere for 20 minutes during the first part of each session, three times per week for 20 sessions over about 7 weeks. The integrated intervention will be the same as Intervention group 3.
Category
Treatment - Devices

8

Description
Intervention group 7: active transcranial direct current stimulation with the anode over the left primary motor cortex and the cathode over the right supraorbital region, without any cognitive intervention. Active stimulation will be delivered at 1 milliampere for 20 minutes per session, three times per week for 20 sessions over about 7 weeks. Participants will watch a silent nature documentary during the session to control for time and attention.
Category
Treatment - Devices

Recruitment centers

1

Recruitment center
Name of recruitment center
Consultation, Psychological, Research and Specialized Services Center of Isfahan Province General De
Full name of responsible person
Mohammad Amin Javedanfar
Street address
Beginning of Sharif Vaghefi Street, Chaharrah-e Naghashi, Isfahan, Iran
City
Isfahan
Province
Isfehan
Postal code
8155113853
Phone
+98 31 3265 5530
Email
m_javedanfar@sbu.ac.ir
Web page address
https://eitaa.com/esfahan_counselling

Sponsors / Funding sources

1

Sponsor
Name of organization / entity
Shahid Beheshti University
Full name of responsible person
Mohammad Amin Javedanfar
Street address
Shahid Beheshti University, Shahid Shahriari Square, Evin, Tehran, Iran
City
Tehran
Province
Tehran
Postal code
1983969411
Phone
+98 21 2990 2761
Email
m_javedanfar@sbu.ac.ir
Grant name
Grant code / Reference number
Is the source of funding the same sponsor organization/entity?
Yes
Title of funding source
Shahid Beheshti University
Proportion provided by this source
100
Public or private sector
Public
Domestic or foreign origin
Domestic
Category of foreign source of funding
empty
Country of origin
Type of organization providing the funding
Academic

Person responsible for general inquiries

Contact
Name of organization / entity
Shahid Beheshti University
Full name of responsible person
Mohammad Amin Javedanfar
Position
PhD Candidate
Latest degree
Master
Other areas of specialty/work
Cognitive Psychology
Street address
Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Shahid Shahriari Square, Evin, Tehran, Iran
City
Tehran
Province
Tehran
Postal code
1983969411
Phone
+98 21 2990 2761
Email
m_javedanfar@sbu.ac.ir
Web page address
https://icbs.sbu.ac.ir/

Person responsible for scientific inquiries

Contact
Name of organization / entity
Shahid Beheshti University
Full name of responsible person
Shahriar Gharibzadeh
Position
Associate Professor
Latest degree
Ph.D.
Other areas of specialty/work
Cognitive Neuroscience
Street address
Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Shahid Shahriari Square, Evin, Tehran, Iran
City
Tehran
Province
Tehran
Postal code
1983969411
Phone
+98 21 2990 2761
Email
s_gharibzade@sbu.ac.ir
Web page address
https://icbs.sbu.ac.ir/~s_gharibzade

Person responsible for updating data

Contact
Name of organization / entity
Shahid Beheshti University
Full name of responsible person
Mohammad Amin Javedanfar
Position
PhD Candidate
Latest degree
Master
Other areas of specialty/work
Cognitive Psychology
Street address
Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Evin, Shahid Shahriari Square, Tehran, Iran. Postal Code: 1983969411
City
Tehran
Province
Tehran
Postal code
1983969411
Phone
+98 21 2990 2761
Fax
Email
m_javedanfar@sbu.ac.ir

Sharing plan

Deidentified Individual Participant Data Set (IPD)
No - There is not a plan to make this available
Justification/reason for indecision/not sharing IPD
Due to confidentiality and ethical considerations related to minor participants, deidentified individual participant data will not be shared.
Study Protocol
Yes - There is a plan to make this available
Statistical Analysis Plan
Yes - There is a plan to make this available
Informed Consent Form
No - There is not a plan to make this available
Clinical Study Report
Not applicable
Analytic Code
Yes - There is a plan to make this available
Data Dictionary
Yes - There is a plan to make this available
Title and more details about the data/document
Study protocol, statistical analysis plan, analytic code, and data dictionary of the randomized, double-blind, sham-controlled trial of simultaneous dual-site transcranial direct current stimulation combined with integrated phonological and fine motor intervention in 9-year-old boys with developmental dyslexia
When the data will become available and for how long
Starting 6 months after publication of the primary results; available for 5 years.
To whom data/document is available
Researchers and academics affiliated with recognized universities and research institutions.
Under which criteria data/document could be used
For scientific and educational purposes only. Requests will be reviewed by the principal investigator for methodological appropriateness and ethical compliance.
From where data/document is obtainable
By email request to the principal investigator: Mohammad Amin Javedanfar, Institute for Cognitive and Brain Sciences, Shahid Beheshti University; m_javedanfar@sbu.ac.ir
What processes are involved for a request to access data/document
Applicants should send a written request by email including their affiliation, purpose of use, and a brief proposal. Requests will be reviewed within 4 weeks; approved documents will be sent electronically.
Comments
There is no further information.
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