Speed of Processing (SoP) Training Plus α-tACS (aMCIUp)

Speed of Processing (SoP) Training Plus α-tACS in People With Mild Cognitive Impairment: a Double Blind, Parallel, Placebo Controlled Trial Study Protocol

The current proposal aims to assess if the combination of Speed of Processing (SoP) training with alpha tACS (α-tACS) is able to increase brain speed of processing as assessed by the Useful Field of View (UFOV) when comparing to SoP training plus sham α-tACS. Moreover, a second aim is to assess if those changes in speed of processing transfer to other cognitive domains, such as memory, language and executive functioning. Furthermore, the mechanisms underlying these interventions will be tested, namely to assess brain connectivity and coherence as assessed by EEG. To that purpose, the aim of the current proposal is to conduct a double-blind, parallel randomized trial assessing the effects of combining SoP with alpha endogenous tACS (either active or sham) in participants with Mild Cognitive impairment (MCI).

Dementia is thought to affect 6.3 million people across Europe and is especially prevalent in people over 85 years old (23.7%). In this sense, several cognitive training programs, alone or in combination with non-invasive brain stimulation have been used in order to ameliorate age-related cognitive impairments, and even to act in a prophylactic manner in order to prevent more extreme deficits, such as the ones presented in mild cognitive impairment, or even dementia. Despite all these efforts, the effects of CT - combined or not - with several forms of non-invasive brain stimulation have been modest at most. The current proposal aims to assess if Speed of Processing (SoP) training combined with alpha tACS (α-tACS) increases speed of processing as assessed by the Useful Field of View (UFOV) when comparing to SoP training and sham α-tACS. Furthermore, association betweens changes in speed of processing and changes in other cognitive domains, such as memory, language and executive functioning will be assessed. Finnaly, the current proposal aims at probing the mechanisms underlying these interventions, namely to test brain connectivity and coherence as assessed by EEG.

SoP training will have a total of four conditions. In condition 1, participants will be asked to identity objects at increasingly brief exposures. For condition 2, identification of stimulus on the center of the screen will be requested from participants, while a second stimulus will appear somewhere in peripheral vision - stimulus duration, difficulty of the central localization task or the area in which targets may be located are used to change the level of difficulty. Condition 3 is similar to condition 2, but visual distractors are added. Finally, for condition 4, an auditory identification component is superimposed over the visual task (Jobe et al., 2001)

UFOV is a measure of the speed of visual processing for rapid detection and localization of targets under conditions of divided visual attention and in the presence and absence of visual clutter at an above chance level (i.e. 75%).

UFOV is a measure of the speed of visual processing for rapid detection and localization of targets under conditions of divided visual attention and in the presence and absence of visual clutter at an above chance level (i.e. 75%).

Executive Composite Score from the Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (NIH EXAMINER)

The NIH examiner executive composite comprises cognitive control, verbal fluency, and working memory assessments. Scores are based on the Item Response theory (IRT), which allows for the contribution of each item score is weighted by how effective that item measures that ability in any part of the continuum. Instead of a maximum or a minimum, higher scores, mean better performance.

Executive Composite Score from the Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (NIH EXAMINER)

The NIH examiner executive composite comprises cognitive control, verbal fluency, and working memory assessments. Scores are based on the Item Response theory (IRT), which allows for the contribution of each item score is weighted by how effective that item measures that ability in any part of the continuum. Instead of a maximum or a minimum, higher scores, mean better performance.

Measure of the speed of visual processing for rapid detection and localization of targets under conditions of divided visual attention and in the presence and absence of visual clutter at an above chance level (i.e. 75%).

Measure of the speed of visual processing for rapid detection and localization of targets under conditions of divided visual attention and in the presence and absence of visual clutter at an above chance level (i.e. 75%).

Measure of the speed of visual processing for rapid detection and localization of targets under conditions of divided visual attention and in the presence and absence of visual clutter at an above chance level (i.e. 75%).

Inclusion Criteria: Community-dwelling adults aged 65 years and older, with cognitive complains in memory or other functions, which have declined over time Exclusion Criteria: Score in the mini mental examination less than 23 (or over 28); Diagnosis of Alzheimer´s Disease, any other medical condition that may predispose participants for a forthcoming decline in function, or that may increase their risk of mortality during the duration of the study. Any contra-indication to tACS, severe sensory losses or communication difficulties that will prevent them from successfully complete the training. Had any cognitive training in the past.

Jobe JB, Smith DM, Ball K, Tennstedt SL, Marsiske M, Willis SL, Rebok GW, Morris JN, Helmers KF, Leveck MD, Kleinman K. ACTIVE: a cognitive intervention trial to promote independence in older adults. Control Clin Trials. 2001 Aug;22(4):453-79. doi: 10.1016/s0197-2456(01)00139-8.

Leite J, Goncalves OF, Carvalho S. Speed of Processing (SoP) Training Plus alpha-tACS in People With Mild Cognitive Impairment: A Double Blind, Parallel, Placebo Controlled Trial Study Protocol. Front Aging Neurosci. 2022 Jul 14;14:880510. doi: 10.3389/fnagi.2022.880510. eCollection 2022.