Brain Mechanisms Underlying Reading Improvement in Central Alexia

NCT ID: NCT02062619

Last Updated: 2016-11-04

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 23 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2014-03-31
• Study Completion Date: 2016-09-30

Brief Summary

Central alexia is a common reading disorder caused by stroke. Patients with central alexia (CA) are slow to read and make frequent errors, and have additional problems with their spoken language.

This study has 3 aims:

1. Investigating the neural networks that support reading in patients with CA Despite being a relatively common syndrome, there have been no functional brain imaging studies of CA. This project will use magnetic resonance imaging (MRI) and magnetoencephalography (MEG) to understand which brain regions are damaged and whether preserved parts of the reading network can be encouraged by therapy to support reading recovery.

2. Testing a new treatment for CA The research team has developed training software called 'iReadMore', which uses a crossmodal approach (written words paired with spoken words) to train reading. This therapy has been shown to be effective in patients with a similar form of reading disorder called pure alexia. The iReadMore software will be adapted to address the reading deficit in CA, and the research will test whether it significantly improves reading ability.

3. Using brain stimulation to enhance behavioural training Transcranial direct current stimulation (tDCS) is a brain stimulation technique that has been shown to improve language performance in healthy controls and stroke patients. This study will test whether tDCS (delivered simultaneously with the 'iReadMore' therapy) significantly enhances reading rehabilitation. Patients will be split into two groups: one will receive a 4 week block of training plus real tDCS first, followed by a 4 week block of training plus sham tDCS; the other group will receive the two therapy blocks in the opposite order. Both groups will ultimately receive the same amount of behavioural therapy and tDCS stimulation. Comparing the reading improvement over the real and sham tDCS blocks will demonstrate whether tDCS enhances the behavioural improvements in reading ability.

Hypothesis:

iReadMore reading therapy will significantly improve single word reading speed in patients with central alexia.

tDCS brain stimulation will significantly enhance the effect of iReadMore therapy, compared to sham stimulation.

Detailed Description

Central alexia is a common acquired reading disorder usually caused by stroke (Leff & Behrmann, 2008). Patients also have generalized language impairments (aphasia), distinguishing it from other acquired reading disorders such as pure alexia, where the reading deficit occurs in isolation. Aphasia is the second most common severe impairment caused by stroke (limb weakness is the first) and reading problems (central alexia) are often associated with it. An analysis of our local database (from which we will be recruiting patients) shows that of the 212 patients with aphasia 14 (66.5%) have central alexia. The severity of central alexia varies across patients but even mild central alexia has a strong detrimental impact on quality of life, preventing patients from returning to work, communicating via email, text or post, or simply reading for pleasure.

Currently, there is no standard treatment for central alexia. Despite its prevalence, few patients receive sufficient reading therapy through the NHS. Only a few computer-based therapies have been tested at the group level (Katz & Wertz, 1997; Cherney, 2010) and only one, a beta version of Oral Reading for Language in Aphasia (by Cherney), is currently available commercially for patients to use. We aim to test the efficacy of 'iReadMore', software designed to improve word reading speed for use in this patient group.

iReadMore is a cross-modal reading training method that was developed as a word reading therapy for patients with pure alexia in a previous study (Woodhead et al, 2013). iReadMore consists of audio-visual pairings of words. It was designed to strengthen orthographic processing of written words by boot-strapping them to auditory percepts and associated higher-order representations (lexical/semantic). Use of the 'iReadMore' software led to a significant improvement in word reading speed for trained words and significantly decreased the word length effect that is characteristic of pure alexia (Woodhead et al, 2013).

The mechanisms underlying the behavioural improvements following iReadMore training were investigated using magnetoencephalography (MEG), an imaging modality optimized to test connectivity-based hypotheses in the hundred millisecond temporal range. Dynamic Causal Modelling (DCM) analyses were used to test training-related changes in connectivity within the reading network comprising. Training strengthened connectivity in the left hemisphere, most notably feedback from left inferior frontal gyrus (IFG) to the visual cortex, a connection which we have shown to be involved early on (within 200ms) when healthy controls read (Woodhead et al, 2012). This led to the hypothesis that feedback from the left IFG drives reading recovery, and that tDCS stimulation of this region, with its connections to both ventral and dorsal temporal cortex, will enhance behavioural training improvements in patients with central alexia.

Although this previous research has focused on pure alexia, a recent pilot study has provided promising evidence that iReadMore may also be beneficial for patients with central alexia. The results demonstrated that iReadMore training and tDCS produced a large, statistically significant improvement of around 600ms per word, a 28% reduction from baseline levels. This effect was observed for both trained and untrained items. Training continued for a further two weeks with sham tDCS with no further significant improvement. A planned fourth tDCS time-point was lost due to patient illness. Although not statistically significant, we observed a trend with performance on untrained items appearing to deteriorate over time. This is in accord with evidence that tDCS may well have a role in consolidation of practice rather than a simple effect on performance alone (Reis et al, 2009).

Summary:

Pilot data has demonstrated that cross-modal iReadMore training is effective in patients with pure alexia; and that its effects are supported by feedback from the left IFG. This work led to the prediction that iReadMore may also be effective in treating the more prevalent and understudied condition of central alexia, and that targeted stimulation of the left IFG with tDCS may enhance the training efficacy. This prediction has already been supported by a preliminary case study, and the present study will expand this further into a group study looking at the effects and mechanisms of rehabilitation of central alexia.

Conditions

Stroke; Brain Injuries; Aphasia

Keywords

Stroke; Aphasia; Acquired reading disorders; Central alexia; Computer based rehabilitation; Transcranial direct current stimulation; tDCS; Magnetoencephalography; MEG; Magnetic Resonance Imaging; MRI

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: DOUBLE

Study Groups

Real tDCS

Transcranial direct current stimulation (tDCS) administered concurrently with computer-based behavioural word reading therapy.

2mA anodal direct current stimulation applied to the left inferior frontal gyrus (IFG) for first 20 minutes of therapy.

Group Type: EXPERIMENTAL

Computer-based behavioural word reading therapy

Intervention Type: BEHAVIORAL

Each patient participates in two blocks of reading training (one with real tDCS, one with sham tDCS). Different words will be trained in each training block.

Each training block comprises 10 hours of reading therapy per week for four weeks (three 1-hour sessions/week at research site; 1-hour of training/day at home)

Real tDCS

Intervention Type: OTHER

Real tDCS 20 minutes per session, three times per week

Sham tDCS

Transcranial direct current stimulation (tDCS) administered concurrently with computer-based behavioural word reading therapy.

Sham tDCS (periodical fade-in and fade-out stimulation routine) applied to the left inferior frontal gyrus (IFG) for first 20 minutes of therapy.

Group Type: SHAM_COMPARATOR

Computer-based behavioural word reading therapy

Intervention Type: BEHAVIORAL

Each patient participates in two blocks of reading training (one with real tDCS, one with sham tDCS). Different words will be trained in each training block.

Each training block comprises 10 hours of reading therapy per week for four weeks (three 1-hour sessions/week at research site; 1-hour of training/day at home)

Sham tDCS

Intervention Type: OTHER

Sham tDCS, 20 minutes per session, 3 sessions per week

Interventions

Computer-based behavioural word reading therapy

Each patient participates in two blocks of reading training (one with real tDCS, one with sham tDCS). Different words will be trained in each training block.

Each training block comprises 10 hours of reading therapy per week for four weeks (three 1-hour sessions/week at research site; 1-hour of training/day at home)

Intervention Type: BEHAVIORAL

Real tDCS

Real tDCS 20 minutes per session, three times per week

Intervention Type: OTHER

Sham tDCS

Sham tDCS, 20 minutes per session, 3 sessions per week

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Over 18 years old
• Left hemisphere stroke or other focal brain injury
• English as a first language
• At least one year post stroke
• Impaired reading ability (defined according to screening with the Comprehensive Aphasia Test, CAT)
• Mild to moderate aphasia (defined according to screening with the CAT)
• Competent to give informed consent

Exclusion Criteria

• Hemorrhagic stroke
• History of significant premorbid neurological or psychiatric illness
• History of developmental reading or speech and language disability
• Severe speech production deficit (defined according to screening with the CAT)
• Damage to tDCS target region (left inferior frontal gyrus)
• Contraindications to MRI scanning (e.g. presence of ferromagnetic implants or other metallic or electronic objects in the body; weight over 24 stone; claustrophobia or pregnancy).

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

University College, London

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Alex Leff, MBBS, PhD

Role: PRINCIPAL_INVESTIGATOR

University College, London

Locations

Institute of Neurology, University College London

London, , United Kingdom

Countries

United Kingdom

References

Kerry SJ, Aguilar OM, Penny W, Crinion JT, Leff AP, Woodhead ZVJ. How Does iReadMore Therapy Change the Reading Network of Patients with Central Alexia? J Neurosci. 2019 Jul 17;39(29):5719-5727. doi: 10.1523/JNEUROSCI.1426-18.2019. Epub 2019 May 13.

Reference Type: DERIVED

PMID: 31085605 (View on PubMed)

Woodhead ZVJ, Kerry SJ, Aguilar OM, Ong YH, Hogan JS, Pappa K, Leff AP, Crinion JT. Randomized trial of iReadMore word reading training and brain stimulation in central alexia. Brain. 2018 Jul 1;141(7):2127-2141. doi: 10.1093/brain/awy138.

Reference Type: DERIVED

PMID: 29912350 (View on PubMed)

Other Identifiers

MR/K022563/1

Identifier Type: -

Identifier Source: org_study_id