Efficacy and Mechanisms of TUS on Cognitive Deficits in Schizophrenia: Based on the Hippocampal-Prefrontal Circuit

Cognitive deficit is a core symptom of schizophrenia related to poorer functional outcome which remains largely treatment refractory. Prior studies indicated that abnormalities in the hippocampus-prefrontal circuit and glutamate/GABA imbalances may be the root causes of cognitive deficits. Transcranial ultrasound stimulation (TUS), an emerging non-invasive neuromodulation technique with deep penetration ability, can modulate neural excitability and plasticity in the hippocampus. This is a 4-week double-blind randomized trial of TUS for cognitive deficits in schizophrenia, with either left hippocampus or left dorsolateral prefrontal cortex (DLPFC) or both targeted. This study aims to determine the efficacy of TUS and to reveal its underlying neural mechanism, especially with the hippocampus-prefrontal circuit, by means of TUS, as to assess cortical inhibition and excitability, EEG source imaging, and multi-model MRI. Neuropsychological assessments will also be conducted to develop the optimized treatment strategy. The study points to a novel and promising therapeutic neuromodulation approach that may improve the functional outcome of schizophrenia, which has been the main cause of mental disability.

Inclusion criteria

• Meet the DSM-5 diagnostic criteria for schizophrenia ;
• Age18-50, right-handed, Han nationality;
• Presence of cognitive deficit: defined as d' value <0.5 in associative memory test;
• Be in a stable condition, received second-generation antipsychotics for at least 4 weeks or more;
• Written informed consent;

Exclusion criteria

• Current or past neurological illness, severe physical diseases, substance abuse or alcohol dependence, mental retardation, pregnancy or lactation;
• Uncooperative or risky patients with high excitement, stupor, disorder of words and deeds, negative suicide, etc.;
• History of MECT or other physical therapy within 6 months;
• History of epilepsy, or epileptic waves on the baseline EEG;
• Ruled out share antiepileptic drugs (carbamazepine, valproic acid salt) or larger doses of benzodiazepine drugs (diazepam > 10mg/day, clonazepam > 2mg/day etc.), if necessary, remain unchanged during the course of treatment;
• Contraindications to TUS and MRI are present.