Effects of intermittent theta burst stimulation (iTBS) on executive function and neuropsychiatric symptoms in older adults with mild to moderate dementia due to Alzheimer's disease: Preliminary findings of a randomized double‐blind clinical trial

Abstract

AbstractBackgroundStudies on brain networks indicate that the functional integration between brain networks decreases progressively with Alzheimer`s disease (AD). The intermittent Theta Burst Stimulation (ITBS) has been shown to modulate the connectivity of DMN administered to parietal (PPC) and dorsolateral prefrontal (DLPFC) cortex.MethodWe selected 9 patients with AD, and a randomized double‐blind clinical trial was performed comparing the active iTBS (n=5) with sham group (n=4)of older adults with mild to moderate AD. Active iTBS condition were submitted to 21 iTBS sessions on the right and left DLPFC and the right and left PPC. All participants were assessed at baseline, week 3,week 6, 3 and 6 months. Executive functions were assessed by validated and standardized tests for this population. Behavioral symptoms were evaluated by Neuropsychiatric Inventory (NPI). The changes in performance between assessments were compared using the reliable change index (RCI).ResultOn phonemic verbal fluency two participants from intervention group show decline of this ability. One of them in the 3rd week (RCI = ‐2.16) and in the 6th week (RCI = ‐3.24). And another only in the 6th week (RCI = ‐3.24). After this period, the performance was similar to that of the baseline for both. Despite this, there were three patients who showed change in phonemic verbal fluency in the third week. One participant from sham group also showed improvement in the sixth week (RCI = 2.16).Regarding working memory, a sham participant showed decline in this ability after the sixth week assessment (RCI = ‐7.38) and this performance remained below that presented in the baseline until the sixth month. And another from intervention group showed improvement in the third week (RCI = 2.46), but from the sixth week on, the performance returned to the same level as the baseline.ConclusionThe improvement and impairment of cognitive variables in comparison to baseline was associated with temporal proximity of neurostimulation procedures for both groups. It is still necessary to expand the sample size to clarify which factors impact on this outcomes.