تاثیر افزودن تحریک فراجمجمه‌ای با جریان الکتریکی مستقیم به آموزش اختصاصی‌سازی حافظه خودزندگی‌نامه‌ای در میزان و ماندگاری اختصاصی‌سازی حافظه خودزندگی‌نامه‌ای در بیماران مبتلا به اختلال افسردگی

مقدمه: آموزش اختصاصی سازی حافظه خودزندگی‌نامه‌ای تاکنون به نتایجی نویدبخش اما عمدتاً گذرا دست یافته است. این مطالعه با توجه به تاثیر مثبت تحریک فراجمجمه‌ای با جریان الکتریکی مستقیم بر روی انعطاف پذیری بافت عصبی، اثرات افزودن آن به این مداخله را بر روی میزان و ماندگاری اثرات آن بر اختصاصی کردن حافظه خودزندگی‌نامه‌ای را در میان بیماران مبتلا به اختلال افسردگی سنجیده است.روش کار: چهل و شش بیمار مبتلا به افسردگی تک قطبی به دو گروه مداخله آموزش اختصاصی ‌سازی حافظه خودزندگی‌نامه‌ای همزمان با تحریک فراجمجمه‌ای با جریان الکتریکی مستقیم حقیقی و شبیه‌ سازی شده تقسیم شدند. تحریک مغزی به صورت همزمان، با جریان آندی و بر روی ناحیه خلفی جانبی قشر پیش‌پیشانی و به صورت شش جلسه دو بار در هفته انجام شد. ارزیابی‌ها توسط سیاهه‌های افسردگی و اضطراب بک و آزمون حافظه خودزندگی‌نامه‌ای انجام شد. یافته ‌ها: پس از نشان دادن همگونی دو گروه از نظر شاخص ‌های جمعیت ‌شناختی، بررسی نتایج توسط آزمون تحلیل واریانس آمیخته نشان داد که افزودن تحریک فراجمجمه‌ای با جریان الکتریکی مستقیم میزان و ماندگاری اثرات مداخله شناختی بر شاخص کلی آزمون را به میزان معناداری افزایش داده است (0/04=p). در میان سه شاخص دیگر حضور سرنخ‌های مرتبط با خاطرات کلی با فاصله بیشتر تفاوت روند تغییرات در میان دو گروه از سطح معناداری تغییرات هم‌راستا بود.نتیجه ‌گیری: بر اساس یافته‌ها افزودن تحریک فراجمجمه‌ای با جریان الکتریکی مستقیم می‌تواند باعث ارتقاء میزان و ماندگاری اثرات مداخله بر روی اختصاصی کردن حافظه خودزندگی‌نامه‌ای شود. با توجه به ارتباط آن با وضعیت خلقی، ارزیابی تغییرات خلق و اضطراب متعاقب تلفیق این دو مداخله با هدف برقراری امکان راهیابی نتایج به عرصه بالینی توصیه می‌شود. پژوهش‌‏های با نمونه بیشتر و سایر شیوه‌های تحریک غیرتهاجمی مغز می‌تواند حائز نتایج قابل توجهی باشد. 

the evaluation of the effects of adding transcranial direct current stimulation to memory specificity training on the extent and durability of its impact on memory specificity

introduction overgeneralized autobiographical memory is one of the most frequent phenomena among the patients affected by a variety of psychiatric disorders, including depression. memory specificity training (mest), as a method trying to modulate the specificity of autobiographical memory, has achieved promising outcomes in improving the specificity, as well as some of the psychiatric symptoms in the targeted patients. the main remaining concern about this intervention, which keeps it from clinical application, is its effects’ short durability and transient nature. transcranial direct current stimulation (tdcs) is a non-invasive brain stimulation method that has been proven to be efficient in the induction of neuroplasticity. based on this hypothesis that the increased neuroplasticity may result in lasting changes in brain circuits, this study aims to investigate the effects of the addition of tcds to mest on the argumentation of the strength and durability of its effects on the specificity of autobiographical memory.methodsforty-six patients affected by depressive disorders were included in the study through an introduction by the collaborator psychiatrist and considering the inclusion and exclusion criteria. the inclusion criteria consisted of a minimum educational level of eighth grade, aged between 20 and 60 years old, and consent to participate. the exclusion criteria were life-threatening conditions, comorbid psychiatric disorders, developmental disorders, any kind of neurological disorders, bipolar depression, consumption of antipsychotic or/and anticonvulsant medications, and medical conditions that may interfere with mood and addiction. the diagnoses were confirmed by the structured clinical interview for dsm-5 (scid-5). patients were divided into two equal groups of twenty-three cases receiving six sessions of mest in addition to tdcs versus sham stimulation. the stimulations lasted for 20 minutes through the online delivery of anodal current with the intensity of 2 milliamps versus sham stimulation, both on the dorsolateral prefrontal cortex. the participants were assessed using beck’s inventories for depression and anxiety and autobiographical memory test, which presented one total index and three specific, general, and alternative sub-indices.resultstwo groups were homogenous, considering age, gender, marital status, and level of education, as well as baseline levels of depression and anxiety according to the scores of beck’s inventories. overall, changes in the score of the indices related to cues demanding specific memories showed significant changes over time that lasted at the follow-up assessment, including specific, alternative, and total indices. the trend of changes between the two groups showed differences toward the hypothesis, but the statistical significance threshold reached only in the total index of the autobiographical memory test. the similar trend in the two other indices related to specific memories, including the specific and alternative indices could not meet the statistical meaningfulness. the trend of changes in the general index of the autobiographical memory test did not show a meaningful trend over time among the whole samples and was also completely independent of the grouping.altogether, the results showed that, firstly, the intervention has been accurately targeted the specific feature of the autobiographical memory, and secondly, the changes are in absolute compatibility with the hypothesis of the study that claimed the addition of tdcs augments the strength and durability of effects induced by mest on the specificity of autobiographical memory.conclusionthe results of this study have shown that the addition of tdcs to mest may increase the effects on the autobiographical memory specificity of mest and their durability. these outcomes, if confirmed with larger and further studies, can promise to bridge the gap between memory specificity training and clinical application.hence, designing and conducting studies investigating the combination of tdcs and/or other non-invasive brain stimulation modalities and mest. such studies should investigate the improvement of the strength and durability of the outcomes at cognitive and clinical levels in the induction of lasting ameliorative effects in patients affected by depressive and other psychiatric disorders that accompany overgeneralized autobiographical memory. ethical considerationscompliance with ethical guidelinethe study relied entirely on voluntary participation. to encourage involvement, information was presented in straightforward language, both in writing and verbally, and all questions from participants were addressed. a written consent form was then obtained from each participant. additionally, the ethics committee of the research institute of cognitive sciences thoroughly reviewed all research procedures, including patient education forms and consent collection. the project received ethics approval with the code ir.ut.iricss.rec.1402.017.authors’ contributionsthe study was derived from borzooyeh naji’s phd dissertation, so he was fully involved in the executive phase and the article’s drafting. seyed mohammad mahdavi was the first supervisor of the project and was mainly involved in the protocol design and data analysis. alireza moradi was the second supervisor, mainly involved in the protocol design and data analysis, as well as reviewing the literature and the article’s draft. amin solhi was the project’s advisor and collaborator psychiatrist who introduced the participants, dressed up the protocol, and received the psychiatric referrals. mohammad sayadnasiri has been project’s advisor and collaborator neurologist who dressed up protocol. all the authors have participated in confirming the final edition of this article.fundingthis study has not received any funding.acknowledgmentsthe authors would like to express their deep gratitude to the staff of tehran imam hussain hospital’s clinic of psychiatry for guiding the participants and making the links and to miss nozanin al-hosseini for coordinating. they especially are grateful to kazemi rezaei and his team for sharing the persian version of the mest protocol they prepared. conflicts of interestthis study is derived from borzooyeh naji’s phd dissertation, registered at the iranian institute for cognitive sciences studies. there is no other conflict of interest to declare.