TMS Treatment of Social Cognition Skills in Mild Cognitive Impairment

EFFECTS OF rTMS TREATMENT ON SOCIAL COGNITION DYSFUNCTIONS IN MILD COGNITIVE IMPAIRMENT: AN PROSPECTIVE, DOUBLE-BINDING, RANDOMIZED, SINGLE CENTRE, EXPLORATIVE STUDY

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: 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). 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. 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.

ripetitive transcranial magnetic stimulation treatment, social cognition, theory of mind, empathy, social perception, social behavior

In the project will be applied a two-site repetitive transcranial magnetic stimulation (rTMS) stimulation. MCI patients that obtained a score ≤ 10 percentiles, at least one performance/domain of social cognition assessment will be considered impaired at social cognition abilities. In the same day of cognitive-behavioral assessment, patients will be randomly assigned to one of the two groups: 1) RR-Gr received 4 weeks of rTMS stimulation of the RTPJ and MPFC; (2) SR-Gr received of the RTPJ and MPFC sham stimulation during the first 2 weeks followed by 2 weeks of real stimulation. Each week of rTMS treatment consisted of five sessions. This paradigm has proven to be effective for improve cognitive performances in AD patients. In the sham condition, a sham coil will be used.

MCI patients with social cognition deficits will receive 2 weeks of placebo treatment, followed by 2 weeks of real rTMS stimulation

A two-site rTMS stimulation delivered by a Magstim unit featuring a double 70 mm cooled coil will be applied. MCI patients will be randomly assigned to one of the two study groups: RR-Gr will receive 4 weeks of rTMS stimulation of the right temporo-parietal junction (RTPJ) and medial prefrontal cortex (MPFC); PL-Gr will receive sham stimulation of the RTPJ and MPFC during the first 2 weeks followed by 2 weeks of real stimulation. Each week of rTMS treatment will consist of five sessions (50 min, one per day). For each area target, a total of 2000 pulses at 20Hz, 3-s train duration, and 28-s inter-train interval at 100% motor threshold (MT) will be delivered per session. A fixed intensity of MT will ensure a more consistent spatial spread of TMS effects in subjects' brains not influenced by differences in individual MT. In the sham condition, a sham coil will be used. Each session lasted for about 60 min including time for set up and 50 min of stimulation.

(visual analogue scale with 100-point scale). Minimum value=0, maximum value=100. Higher score means a better outcome.

Inclusion Criteria: Subjects aged 50 to 85 years old, inclusive, at the time of informed consent; Must have at least 5 years of education or work experience to exclude mental deficits other than MCI; Must meet Petersen's criteria for mild cognitive impairment, and must have: Clinical dementia rating global score of 0.5; Mini-Mental State Examination score between 24 and 30; Must have a score ≥ 26.5 at Token test to ensure that subjects have the ability to understand the instructions and procedures; Must have a score < 29 at Beck Depression Inventory to exclude major depression that could compromise the patient's ability to engage in the study; Apart from a clinical diagnosis of MCI, the subject must be in good health; Must be on stable dose of antidepressant (if applicable) for at least 2 months prior to the enrolment. Exclusion Criteria: Any uncontrolled medical or neurological/neurodegenerative condition (other than MCI); Clinical significant unstable psychiatric illness requiring treatment with neuroleptic; Transient ischemic attack, stroke, or any unexplained loss of consciousness or severe ongoing stressor within 1 year prior to screening; History of seizure within10 years prior to screening; Recent history of alcohol or substance abuse or use of cannabinoids; Any other medical conditions that are not stable or controlled, or could affect the subject's safety or interfere with the study assessments and treatment; Contraindication to having TMS treatment; Inability to understand the purpose of the study or to comply with study requirements.

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