Connectivity-Guided Individualized iTBS of the Posterior Parietal Cortex in Enduring Anorexia Nervosa: Network-Level Target Engagement and Multimodal Response in a Single Case

Aims: Anorexia nervosa (AN) is a severe, often enduring disorder with scarce biological treatments, largely unable to address its core implicit features: habit-like food restriction and body-experience disturbances. We report a single-case application of resting-state connectivity-guided intermittent theta-burst stimulation (iTBS) to the posterior parietal cortex (PPC), a hub for body representation, peripersonal space, and affordance-based action. Methods: A 31-year-old woman with 12 years of treatment-resistant restricting AN, enrolled in an ongoing sham-controlled feasibility trial, underwent 20 active iTBS sessions to an individualized left-PPC site maximally coupled with a body-representation × affordance reference network, assessed at baseline, post-treatment, and four-month follow-up. Results: The protocol was fully feasible and well tolerated, without significant adverse events. Clinical change was gradual, with most of the weight gain occurring after the stimulation period: BMI rose from 15.65 to 16.01 at four-month follow-up and 16.40 over subsequent clinical follow-up. Blinded global improvement was minimal; anxiety fell below threshold, whereas eating-disorder and body-shape scores remained at floor. Target–reference connectivity increased in the a priori direction, toward the healthy-control mean. Exploratory measures changed heterogeneously, only partly tracking engagement. Conclusion: This case supports the feasibility and mechanistic plausibility of individualized parietal targeting in enduring AN, motivating a controlled trial to test its efficacy. Trial Registration: The parent trial is registered on ClinicalTrials.gov (NCT07106645).