The Effect of Transcranial Direct Current Stimulation on Decision Making and Cognitive Flexibility in Gambling Disorder

Istanbul University20 enrolled

Overview

The investigators conducted a double-blind randomised sham-controlled study. Upon enrollment into the study, participants were randomly assigned to one of two conditions: (i) active group: anodal stimulation over the right dlPFC (n = 10) or (ii) sham stimulation group (n = 10). Participants and raters were blinded to the condition. Subsequently, the participants were administered the IGT and the Wisconsin Card Sorting Test by a trained neuropsychologist in a quiet laboratory. A computerized version of standard IGT was used. The order of the tasks performed in a single session was randomised. After the psychiatric and neurocognitive assessment, participants received three sessions of 20-minute active or sham anodal tDCS (once a day, every other day). Wisconsin Card Sorting Test and a modified version of Iowa Gambling Test were readministered after the last application. The order of the tasks was randomized again. A brief questionnaire on study blinding was also administered. Safety was assessed through open-ended questions based on the tDCS adverse events questionnaire

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Gambling Disorder

Interventions

Transcranial direct current stimulation (tDCS) is a safe method for non-invasively modulating cortical excitability through the use of weak electrical currents (usually of 1-2 mA) circulating between two scalp electrodes (i.e., an anode and a cathode) placed over the target cortical regions. The effects of tDCS on brain activity are polarity-dependent, such that anodal stimulation generally enhances cortical excitability by depolarizing cell membranes and increasing neuronal firing rates, while cathodal stimulation generally results in the opposite effect. Because of its neural effects, tDCS has been increasingly used to gauge the functional relationship between cognitive/behavioural dimensions and putatively relevant neurocircuitry

Eligibility

Sex: MALEMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Participants meeting Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria for gambling disorder * Being right-handed * Being 18-65 years old * Being drug-free Exclusion Criteria: * Current DSM-5 diagnosis of major depressive disorder * Current or previous DSM-5 diagnosis of alcohol and substance use disorders, schizophrenia, bipolar disorder, or other psychotic disorder * Drug Use in the past 4 weeks of any medication with known pro-convulsant action or current regular use of any psychotropic medications (benzodiazepines, antipsychotic medications, tricyclic antidepressants, anti-epileptics, mood stabilizers) * Any history of any clinically significant neurological disorder, including organic brain disease, epilepsy, stroke, brain lesions, multiple sclerosis, previous neurosurgery, or personal history of head trauma that resulted in loss of consciousness for \> 5 minutes and retrograde amnesia for \> 30 minutes, * The presence of mental retardation diagnosis (previously identified) * Any personal or family history (1st degree relatives) of seizures other than febrile childhood seizures * Illiteracy, deficient language or refusal to participate.

Outcomes

Primary Outcomes

Changes in the Iowa Gambling Task net score

Iowa Gambling Task net score is the total score of the task (between -100 and 100) that generally assesses the decision making under ambiguity, but also assesses the decision making under risk at the later stages. Higher scores in the task represents better decision making and healthy people generally have scores above 8-10 in the task.

Time frame: Baseline, after tDCS treatment

Changes in the number of perseverative errors in Wisconsin Card Sorting Task

Wisconsin Card Sorting Task is the widely used task to assess frontal lobe functions such as cognitive flexibility, set shifting and abstraction abilities. The participants were required to match response cards to 4 stimulus cards along 1 of 3 dimensions (colour, form or number) on the basis of verbal feedback (correct or incorrect). The participants were not given any information about the dimensions. After sorting a series of 10 cards in 1 category, participants were asked to sort the cards in a different category. The number of perseverative errors in Wisconsin Card Sorting Task is the most robust variable of the task to assess cognitive flexibility. Higher scores show an impairment of cognitive flexibility