Physiological aging is often associated with memory function decline. Recently, the use of transcranial direct current stimulation (tDCS), a type of non-invasive brain stimulation, has been combined with adaptive working memory training interventions in healthy older adults, providing evidence for a significant improvement in memory functions. To the best of our knowledge, no study addressed the use of strategic memory training coupled with the use of tDCS in normal aging. Strategic memory trainings allow to improve participants' performance in the practiced task and to generalize the use of memory strategies to new materials. This Randomized Controlled Trial (RCT) aims to evaluate the effectiveness of a combined intervention associating strategic memory training with the use of tDCS. Healthy older adults and participants with subjective cognitive decline will be recruited and randomly assigned to the experimental group (strategic memory training + ACTIVE tDCS) or the control group (strategic memory training + SHAM tDCS). All participants will be evaluated on transfer and practiced tasks before (T0) and after (T1) the treatment and during follow-up visits, scheduled at 1 month (T2) and 3 months (T3) after the intervention.
The use of cognitive functions such as memory is essential for the execution of daily activities and represents a crucial element for autonomy maintenance during aging. It is known that the physiological cognitive decline associated with aging also involves memory and can significantly impact the older person's independence. For these reasons, great interest has been generated by two tools that have proved to be decisive in supporting memory functions: non-invasive neurostimulation and memory training. Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation that modulates brain activity by employing a direct current delivered through electrodes applied to the scalp. Recently, the use of tDCS has been combined with training interventions focused on working memory in healthy older adults, providing evidence of a significant improvement in memory function when memory training is associated with the use of tDCS compared to when it is performed without it. In particular, adaptive memory trainings coupled with stimulation of the dorsolateral prefrontal cortex provide benefits that last also at follow-up visits after 1 or 3 months, especially in participants who exhibit a lower baseline performance. While it was observed that adaptive working memory training alone is unable to modulate brain plasticity mechanisms, it was hypothesized that tDCS can modulate brain plasticity by acting through long-term potentiation (LTP) mechanisms and that it can modulate brain neurotrophic factor (BDNF), a protein that plays a relevant role in LTP. Several adaptive memory trainings focused on working memory, which is essential for decision-making processes and daily activities. Even if promising results have been shown so far, it appears that no study addressed the implementation of strategic memory training coupled with the use of tDCS. Adaptive trainings allow improving the performance in each task by gradually increasing its difficulty, without however resorting to teaching a strategy. Strategic memory trainings permit not only to improve participants' performance in the practiced task but also to generalize the use of memory strategies to new tasks. Intending to prevent cognitive impairment, using these intervention methods in healthy aging and the prodromal phases can be useful. To this end, subjective cognitive decline (SCD) indeed represents an intermediate state between normal cognition and mild cognitive impairment (nMCD) and may predict the development of objective cognitive decline. In this frame, the primary goal of this double-blind randomized controlled trial is to assess whether the application of transcranial direct current stimulation during strategic memory training (on-line neurostimulation) enhances the effect of strategic memory training. The follow-up visits allow for investigating whether eventual improvements are preserved over time and if this combined intervention affects the evolution of cognitive decline. The treatment protocol consists of 5 sessions (2/3 session/week, 1 hour/day) of strategic memory training combined with on-line tDCS (anodic tDCS, 2mA for 20 minutes, versus sham tDCS, applied to the dorsolateral prefrontal cortex - DLPFC). Healthy old participants will be recruited from the general population. Participants with subjective cognitive decline (SCD) are recruited from Neuropsychology/Alzheimer's Disease Assessment Unit and Neurorehabilitation Unit of IRCCS Mondino Foundation. The diagnosis of SCD is formulated based on a comprehensive neuropsychological evaluation (baseline cognitive assessment - T0) according to the guidelines presented in the literature. At T0, the following standardized tests are used: * Global cognitive function is assessed using Mini-Mental State Examination (MMSE); * Cognitive reserve is assessed using Cognitive Reserve Index Questionnaire (CRIq); * Mood is assessed using Geriatric Depression Scale (GDS). At T0, practiced and not practiced memory tasks (Bottiroli et al., 2013) will be administered to the participants as pre-tests: 1. Associative learning; 2. List learning; 3. Name-face learning; 4. Place learning; 5. Text learning; 6. Grocery learning; Participants who met the inclusion and exclusion criteria are enrolled and randomly assigned to the experimental group (strategic memory training + ACTIVE tDCS) or control group (strategic memory training + SHAM tDCS).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
56
ACTIVE transcranial direct current stimulation( tDCS)
SHAM tDCS
Associative learning test scores
Participants are presented with 40 paired associates. Pairs consist of words chosen from Paivio, Yuille, and Madigan (1968) concreteness and imagery norms and from De Mauro, Mancini, Vedovelli, and Voghera (1993) word frequency norms. Each pair is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the pairs for up to 20 minutes. After study, each stimulus is individually presented, and participants Are asked to write the corresponding response
Time frame: Immediately after the intervention program (T1).
Associative learning test scores
Participants are presented with 40 paired associates. Pairs consist of words chosen from Paivio, Yuille, and Madigan (1968) concreteness and imagery norms and from De Mauro, Mancini, Vedovelli, and Voghera (1993) word frequency norms. Each pair is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the pairs for up to 20 minutes. After study, each stimulus is individually presented, and participants Are asked to write the corresponding response
Time frame: 1 month (T2) after the end of the intervention program.
Associative learning test scores
Participants are presented with 40 paired associates. Pairs consist of words chosen from Paivio, Yuille, and Madigan (1968) concreteness and imagery norms and from De Mauro, Mancini, Vedovelli, and Voghera (1993) word frequency norms. Each pair is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the pairs for up to 20 minutes. After study, each stimulus is individually presented, and participants Are asked to write the corresponding response
Time frame: 3 months (T3) after the end of the intervention program.
List learning tests scores
Participants are presented with 40 words. Words are also taken from Paivio Yuille, and Madigan (1968) and De Mauro, Mancini, Vedovelli, and Voghera (1993) norms. Each word is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the words for up to 20 minutes. After study, participants are asked to write down as many words as they could remember (in any order) on an answer sheet.
Time frame: Immediately after the intervention program (T1).
List learning tests scores
Participants are presented with 40 words. Words are also taken from Paivio Yuille, and Madigan (1968) and De Mauro, Mancini, Vedovelli, and Voghera (1993) norms. Each word is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the words for up to 20 minutes. After study, participants are asked to write down as many words as they could remember (in any order) on an answer sheet.
Time frame: 1 month (T2) after the end of the intervention program.
List learning tests scores
Participants are presented with 40 words. Words are also taken from Paivio Yuille, and Madigan (1968) and De Mauro, Mancini, Vedovelli, and Voghera (1993) norms. Each word is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the words for up to 20 minutes. After study, participants are asked to write down as many words as they could remember (in any order) on an answer sheet.
Time frame: 3 months (T3) after the end of the intervention program.
Name-face learning test scores
Participants are presented with 20 black and white photographs of faces (2.75 x 4) paired with the last name printed below it. The 20 name-face cards are handed to participants, who are instructed to study the pairs for up to 20 minutes. After study, each face is individually presented, and participants are asked to write down the name that had been previously paired with it.
Time frame: Immediately after the intervention program (T1).
Name-face learning test scores
Participants are presented with 20 black and white photographs of faces (2.75 x 4) paired with the last name printed below it. The 20 name-face cards are handed to participants, who are instructed to study the pairs for up to 20 minutes. After study, each face is individually presented, and participants are asked to write down the name that had been previously paired with it.
Time frame: 1 month (T2) after the end of the intervention program.
Name-face learning test scores
Participants are presented with 20 black and white photographs of faces (2.75 x 4) paired with the last name printed below it. The 20 name-face cards are handed to participants, who are instructed to study the pairs for up to 20 minutes. After study, each face is individually presented, and participants are asked to write down the name that had been previously paired with it.
Time frame: 3 months (T3) after the end of the intervention program.
Place learning test scores
Participants are presented a map of a city. The map includes the location and name of 20 target places (e.g., bank) across the streets of an imaginary city. They are given up to 15 minutes to study, and then they have to write the position and name of places on a blank map.
Time frame: Immediately after the intervention program (T1).
Place learning test scores
Participants are presented a map of a city. The map includes the location and name of 20 target places (e.g., bank) across the streets of an imaginary city. They are given up to 15 minutes to study, and then they have to write the position and name of places on a blank map.
Time frame: 1 month (T2) after the end of the intervention program.
Place learning test scores
Participants are presented a map of a city. The map includes the location and name of 20 target places (e.g., bank) across the streets of an imaginary city. They are given up to 15 minutes to study, and then they have to write the position and name of places on a blank map.
Time frame: 3 months (T3) after the end of the intervention program.
Text learning test scores
Participants are presented with a short story with 22 major ideas (e.g., It was a quiet Sunday at Tirano railway station./ The locomotive, to which the carriages had already been coupled, was standing on the track./ The engine driver and his assistants got down to make sure everything was all right./ Some damage to the brakes...). They have up to 15 minutes to study the story, and then they are asked to recall and write down as much as possible from memory.
Time frame: Immediately after the intervention program (T1).
Text learning test scores
Participants are presented with a short story with 22 major ideas (e.g., It was a quiet Sunday at Tirano railway station./ The locomotive, to which the carriages had already been coupled, was standing on the track./ The engine driver and his assistants got down to make sure everything was all right./ Some damage to the brakes...). They have up to 15 minutes to study the story, and then they are asked to recall and write down as much as possible from memory.
Time frame: 1 month (T2) after the end of the intervention program.
Text learning test scores
Participants are presented with a short story with 22 major ideas (e.g., It was a quiet Sunday at Tirano railway station./ The locomotive, to which the carriages had already been coupled, was standing on the track./ The engine driver and his assistants got down to make sure everything was all right./ Some damage to the brakes...). They have up to 15 minutes to study the story, and then they are asked to recall and write down as much as possible from memory.
Time frame: 3 months (T3) after the end of the intervention program.
Grocery learning test scores
Participants are presented with a list of 40 grocery items (e.g., butter). Each item is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the pairs for up to 15 minutes. In the recall phase, participants are asked to write down as many grocery items (in any order) as they could remember.
Time frame: Immediately after the intervention program (T1).
Grocery learning test scores
Participants are presented with a list of 40 grocery items (e.g., butter). Each item is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the pairs for up to 15 minutes. In the recall phase, participants are asked to write down as many grocery items (in any order) as they could remember.
Time frame: 1 month (T2) after the end of the intervention program.
Grocery learning test scores
Participants are presented with a list of 40 grocery items (e.g., butter). Each item is printed in the middle of a 5 x 7 index card. The 40 cards are handed to participants, who are instructed to study the pairs for up to 15 minutes. In the recall phase, participants are asked to write down as many grocery items (in any order) as they could remember.
Time frame: 3 months (T3) after the end of the intervention program.
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