tDCS and Cognitive Efficiency

Study Overview
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Brief Summary
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Normal aging is associated with a progressive decline in cognitive functions, especially memory. This decline in cognitive function can negatively impact the quality of life of older adults. Although there are currently few possibilities to prevent and/or slow the signs of cognitive decline, both those associated with age and neurodegenerative pathologies, one of the non-invasive brain stimulation techniques that has gained attention in recent years is Transcranial Direct Current Stimulation (tDCS). tDCS is a technique based on the application of a low-intensity (< 2 mA) direct electrical current between two large-area electrodes placed on various surface areas of the head. Moreover, according to safety-related meta-analyses it is a very safe technique, without any major side effects, provided that internationally established safety protocols are taken into account in its application. This technique has recently been investigated as a potential treatment for both healthy elderly people and people with mild cognitive impairment and Alzheimer's disease in several cognitive variables, having shown encouraging results in working memory learning curves, modulation of plasticity and recognition tasks. This project aims to implement an intervention using transcranial direct current stimulation in healthy older adults, MCI and AD. The main objective is to test if there is an improvement in cognitive efficiency and if the changes are maintained over time (1 month). For this purpose, the effect of the technique will be studied on participants assigned to treatment and control groups, analyzing the possible modifications in the following cognitive variables: cognitive plasticity and learning potential, recognition and familiarity and false alarms.

Official Title
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Non-invasive Transcranial Direct Current Stimulation to Improve Cognitive Efficiency

Conditions
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Aging, Mild Cognitive Impairment, Alzheimer Disease

Intervention / Treatment
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* Device: Transcranial direct current stimulation (tDCS)
* Device: Sham stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: For the group of healthy older adults: MEC score greater than 26 points. GDS between 1 and 3. For the MCI group: MEC score between 21 and 26 points. GDS between 1 and 3. For the mild EA group: MEC score between 18 and 23 points. GDS between 3 and 4. Exclusion Criteria: Presentation of contraindications to tDCS (presence of intracranial metal implants, intracranial hypertension, comitial risk). Significant asymptomatic neurovascular disease History of previous symptomatic stroke Alcohol or drug abuse/dependence Severe psychiatric symptoms Depressive symptoms higher than mild

Ages Eligible for Study
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Minimum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: sham versus stimulation
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: tDCS. Transcranial direct current stimulation<br>The stimulation time was 20 minutes, with an initial and final ramp of 30 seconds so that the participant could adapt to the sensation of the current. 10 sesions. Constant current intensity of 2 mA The anode was placed on position F7, coinciding with the dorsolateral prefrontal cortex, and the cathode was placed on Fp2, coinciding with the right supraorbital area (rSO). | Device: Transcranial direct current stimulation (tDCS)<br>* 10 sessions of tDCS stimulation on dorsolateral prefrontal cortex with the apparatus HDC stimulator (Newronika TM)<br>* Other names: Transcranial direct current stimulation;|
| Sham Comparator: Sham stimulation<br>The sham group received direct current only on the ramps to generate a sensation of the effect. | Device: Sham stimulation<br>* The sham group received direct current only on the ramps to generate a sensation of the effect.10 sessions<br>* Other names: Transcranial direct current stimulation;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Complutense Verbal Learning Test (TAVEC) | The evaluator reads a 16-word shopping list in five different essays and in each of them the evaluated person must mention those words that he or she remembers. After 20 minutes, the subject is asked to remember them again | 20 minutes | 
| Digits Wechsler Intelligence Scale for Adults-III (WAIS-III) | The digits forward task assesses immediate recall. It requires the participant to repeat a sequence of numbers in the same order in which they were read. On the digits backward task, the subject must repeat a sequence of numbers in the reverse order of their presentation. The task is used to assess working memory. | 5 minutes | 
| Experimental task - Recognition familiarity and false alarms | The Half condition included two lists of 50 words each, formed entirely from the following letters of the Spanish alphabet: a, e, u, b, d, g, j, n, r, z (List A) or i, o, c, f, h, l, m, p, s, t, v, y (List B). List C (Entire condition) contained 50 words formed from the entire alphabet, with the only criterion being that each word had to contain at least one letter from List A and at least one letter from List B. | 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| MMSE | This test is evaluated on a maximum of 30 points. Participants with scores equal to or below 23 would be considered cognitively deficient. | 5-10 minutes | 
| Barcelona test (BT) | In this test, the subject is considered to have a good categorical evocation when he is able to evoke more than 16 animals in 1 minute and a good verbal fluency when he is able to evoke more than 19 words beginning with p in 3 minutes | 5 minutes |