Cognitive Dysfunction, Schizophrenia
Conditions
Keywords
schizophrenia, tDCS, tACS, Cognition, dorsolateral prefrontal cortex
Brief summary
The purpose of this study is to investigate different stimulation intensities and frequencies of transcranial direct and alternating current stimulation over the dorsolateral prefrontal cortex for cognitive improvement in schizophrenia.
Detailed description
In this randomized, double-blind study, 50 patients diagnosed with schizophrenia are randomly assigned into two arms. The first group receives transcranial direct current stimulation (tDCS) at three intensities (2 mA, 3 mA, and sham) and the second group receives transcranial alternating current stimulation (tACS) at three different frequencies (8 Hz, 40 Hz, and sham) over the left dorsolateral prefrontal cortex for 20 min. There are at least 72 hours between stimulation sessions. The patients conduct three cognitive tasks from the CANTAB neuropsychological battery for schizophrenia during stimulation including a working memory task, a cognitive flexibility task, and an emotion recognition task. Mood stability is also evaluated before and after each stimulation session with the Positive and Negative Affect Scale (PANAS).
Interventions
DEVICEtranscranial direct current stimulation (tDCS)
In tDCS, direct electrical currents at the intensity of interest (2 mA for example) are generated by an electrical stimulator and are noninvasively delivered to the scalp through a pair of saline-soaked sponge electrodes (7×5 cm).
DEVICEtranscranial alternating current stimulation (tACS)
In tACS, alternating electrical currents at the frequency of interest (8 Hz for example) are generated by an electrical stimulator and are noninvasively delivered to the scalp through a pair of saline-soaked sponge electrodes (7×5 cm).
Sponsors
Ardabil University of Medical Sciences
Leibniz Research Centre for Working Environment and Human Factors
The National Brain Mapping Laboratory (NBML)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Caregiver, Outcomes Assessor)
Masking description
Allocation Concealment is used to perform a random sequence on study participants. Also, non-transparent envelopes sealed with random sequences will be used, in a way that each random sequence is recorded on a card, and the cards are placed in the envelope in order. In order to maintain a random sequence, the envelopes are numbered in the same way on the outer surface. Finally, the lids of the envelopes are glued and placed inside a box. At the beginning of the registration, according to the order of entry of the eligible participants, one of the envelopes will be opened in order and the assigned group of the participant will be revealed.
Intervention model description
Parallel group and each group with crossover design
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
No
Inclusion criteria
* Diagnosis of schizophrenia based on DSM V, * Being 18-50 years old (male and female) * If female, negative urine pregnancy test * feasibility for tDCS interventions according to safety guidelines * stable medication regime especially the classical neuroleptics and all CNS-activating medications, if taken, 4-6 weeks before the experiment * fluency in the native language * right-handed * Required written informed consent signed by patients' guardian
Exclusion criteria
* pregnancy * alcohol or substance dependence * history of seizure * history of neurological disorder * history of head injury * Presence of ferromagnetic objects in the body that are contraindicated for brain stimulation of the head (pacemakers or other implanted electrical devices, brain stimulators, some types of dental implants, aneurysm clips, metallic prostheses, permanent eyeliner, implanted delivery pump, or shrapnel fragments) or fear of enclosed spaces).
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Spatial Working Memory behavioral performance | During procedure (4 minutes) | The test begins with a number of coloured squares (boxes) shown on the screen. The aim of this test is that by selecting the boxes and using a process of elimination, the participant should find one yellow 'token' in each of a number of boxes and use them to fill up an empty column on the right-hand side of the screen. |
| executive function behavioral performance | During procedure (8-10 minutes) | The participant is shown two displays containing three coloured balls. The test administrator first demonstrates to the participant how to move the balls in the lower display to copy the pattern in the upper display and completes one demonstration problem, where the solution requires one move. The participant must then complete three further problems, one each requiring two moves, three moves and four moves. Next the participant is shown further problems and must work out in their head how many moves the solutions require and then select the appropriate box at the bottom of the screen to indicate their response |
| Emotional recognition behavioral performance | During procedure (60 minutes) | Computer-morphed images derived from the facial features of real individuals, each showing a specific emotion, are displayed on the screen, one at a time. Each face is displayed for 200 milliseconds and then immediately covered up to prevent residual processing of the image. The participant must select which emotion the face displayed from 6 options (sadness, happiness, fear, anger, disgust or surprise) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| The Positive and Negative Affect Schedule (PANAS) | through study completion in each experimental session up to 1 hour | The Positive and Negative Affect Schedule (PANAS) is a self-report questionnaire that consists of two 10-item scales to measure both positive and negative affect. Each item is rated on a 5-point scale of 1 (not at all) to 5 (very much). |
Countries
Iran
Outcome results
None listed