Effects Of Transcranial Direct Current Stimulation On Cognitive Function And White Matter Fiber Integrity In Patients With Stroke

Purpose:Post-stroke cognitive impairment（PSCI）is a series of syndromes that meet the diagnostic criteria of cognitive impairment within 6 months after stroke.The incidence of PSCI in stroke patients is as high as 80.97%.At present,the therapeutic effect of drugs used to treat PSCI is limited.Long-term use of drugs will cause some patients to have adverse reactions,which will affect the compliance of patients.As a non-invasive neurological regulation technique,transcranial direct current stimulation（tDCS）has been widely used in clinic because of its safety and effectiveness,simple operation and good patient compliance.It has been reported that tDCS treatment has a certain effect on PSCI,but its specific mechanism is not clear.Current studies suggest that tDCS may play a role by changing the functional connectivity of related areas of the brain or the fiber connectivity of white matter in related regions.The inferior fronto-occipital fasciculus（IFOF）is a white matter fiber associated with cognitive function,and we infer that tDCS may play a role in cognitive function by affecting the integrity of IFOF.Therefore,this study creatively used diffusion tensor imaging（DTI）to observe the effect of tDCS on the integrity of IFOF,and to further explore whether cognitive function is related to the integrity of IFOF in stroke patients.Methods:In this study,30 patients with PSCI who met the inclusion criteria were recruited from July 2021 to February 2022 in the Department of Rehabilitation Medicine,affiliated hospital of Qingdao University.According to the random scheme pre-determined by SPSS,the patients were divided into experimental group（n=15）and control group（n=15）.Patients in both groups were given basic drug therapy（mainly including hypotension,hypoglycemia,etc.,specific medication was adjusted according to the patient’s condition）and routine rehabilitation training（including exercise therapy,occupational therapy,physical factor therapy and cognitive function training）.In order to eliminate interference as far as possible,none of the patients in the two groups were treated with drugs to improve cognitive function.On this basis,the experimental group was treated with tDCS,and the control group was treated with tDCS sham stimulation.Before treatment and 3 weeks after treatment（after treatment）,Minimum Mental State Examination（MMSE）and Montreal Cognitive Assessment（Mo CA）were used to evaluate patients’cognitive function,Modified Barthel Index（MBI）was used to evaluate patients’self-care ability,at the same time,the changes of IFOF integrity were evaluated by Fractional Anisotropy（FA）,Axial Diffusion（DA）and Radial Diffusion（DR）in DTI.Results:Before treatment,there was no significant difference in age,sex,years of education,type of stroke,location of lesion and course of disease between the two groups（P>0.05）,and there was no significant difference in the scores of MMSE,MOCA,MBI and the values of FA,DA and DR between the two groups（P>0.05）.The scores of MMSE,Mo CA and MBI in the two groups were significantly higher than those before treatment（P<0.05）,the scores of MMSE（24.27±4.74）,MOCA（22.00±4.72）,MBI（71.67±13.71）in the experimental group after treatment were significantly better than those in the control group after treatment in MMSE（20.00±5.90）,MOCA（16.73±8.10）,MBI（62.67±16.46）,the difference was significant（P<0.05）.After treatment,the average value of FA（0.460±0.045）,DA[（1.360±0.106）′10^-3],DR[（0.587±0.092）′10^-3]in the experimental group were significantly different from those before treatment（P<0.05）.Compared with the control group,the average value of FA（0.425±0.048）,DA[（1.293±0.046）′10^-3],DR[（0.653±0.074）′10^-3]of IFOF after treatment had significant difference（P<0.05）.Correlation analysis showed that the average FA of IFOF was positively correlated with MMSE and MOCA scores in both groups.Conclusion:tDCS combined with routine cognitive training can significantly improve the cognitive function and the ability of daily activities of patients with PSCI.In addition,tDCS can improve the microstructural integrity of ipsilateral IFOF,and the improvement of cognitive function is significantly correlated with the change of microstructural integrity of ipsilateral IFOF,which may be one of the mechanisms of tDCS improving PSCI.