TMS Treatment of Social Cognition Skills in Mild Cognitive Impairment

Overview

Social cognitive abilities are impaired in around 17% of subjects with mild cognitive impairment (MCI), and might not reflect upon functional status. Compared to healthy controls, MCI showed impairments in theory of mind (ToM) and facial emotion recognition. Moreover, in amnesic MCI patients, reduced ToM ability appears to be correlated with worse performances at several cognitive performances. These findings, in agreement with previous evidence, confirm that impaired social cognition might occur prior to dementia: typically elderly start to show impairment in the complex ToM levels, which is found also in MCI patients and proceeds further in AD patients. Thus, the treatment of these aspects has the potential to influence the trajectory of neurodegeneration. In the last decade, it has been increasingly evident the effectiveness of active stimulation of brain regions with repetitive transcranial magnetic stimulation (rTMS), to improve cognitive and functional performances in patients with dementia. On the other hand, brain imaging techniques and TMS stimulations have identified two main areas responsible for human social cognition- the medial prefrontal cortex (MPFC) and the right temporo-parietal junction (RTPJ). In this project, we hypothesized that an improvement of social cognition skills may be obtained in MCI patients by using the rTMS on two main areas responsible for human social cognition- the medial prefrontal cortex (MPFC) and the right temporoparietal junction (RTPJ). Moreover, it expects that rTMS treatment may also contribute to improving cognitive abilities and neuropsychiatric aspects partially modulated by the same networks stimulated.

This is a prospective, double-binding, cross-sectional, randomized, sham-controlled, and single-center project aimed to investigate the effect of rTMS treatment of social cognition abilities in MCI subjects at 2 and 4 weeks, and after 8 weeks from baseline. All patients will be recruited at Clinical Neuroscience Institute, Department of Neurology, Regional Civic Hospital, Lugan; Department of Geriatric Italian Hospital Viganello; and Department of Geriatric, Beata Vergine Hospital Mendrisio; Southern Switzerland, Switzerland. Primary objective: 1\. To investigate whether the application of high-frequency rTMS, for 2 or 4 weeks, to the RPTJ and MPFC resulted in social cognitive improvements. Secondary objectives: 1. To verify whether the social cognition benefits previously recorded might persist after 8 weeks the end of the stimulation, with a major benefit with a longer rTMS application (4 weeks). 2. To investigate whether the application of high-frequency rTMS, at 2 weeks or 4 weeks, to the RPTJ and MPFC contributes to improve cognitive functions as well as neuropsychiatric (depression) and functional aspects. 3. To verify whether the cognitive functions, neuropsychiatric aspect, and functional benefits previously recorded persist after the end of the rTMS stimulation. Primary analysis: To investigate the behavioral effects induced by the rTMS protocol after 2 and 4 weeks of daily stimulation on social cognition skills, executive/attentive functions, neuropsychiatric and functional aspects will be used a mixed-model ANOVA, considering the group as a between-subjects factor, and time as a within-subject factor. Secondary Analyses: To investigate the direct or mediated rTMS effect on social cognition skills, a multivariate linear regression analysis will be done for each social cognition measure (ToM, empathy, social perception, social behavior) changes after rTMS treatment at 2 and 4 weeks as the dependent factor, separately, and appropriate screening/baseline dependent variables and rTMS groups as independent factors. The evaluation and treatment of social cognition alterations in subjects with MCI can be useful for two main aspects: first, the mild cognitive and behavior impairment of these subjects favor a better answer at the treatment, both at the behavioral level and in terms of brain structural and functional response; second, treatment of these abilities in MCI population might retard the conversion to dementia. More importantly, the detection of predominant social cognition alteration in early phases of cognitive decline might be potentially helpful to differentiate individuals who will develop frontotemporal dementia. Therefore, it is important to investigate and define a treatment protocol to limit social cognition disturbances in MCI.