Using specific EEG biomarkers in methamphetamine-dependent individuals, this study systematically probes closed-loop tACS based on brain states, assessing dosage, neurologic and behavioral effects, while comparing its efficacy with traditional open-loop tACS methods.

The current study delineates a robust correlation between prefrontal cortex EEG signals and the psychological craving associated with methamphetamine usage. Dependents exhibit heightened β oscillation energy in the MPFC region and diminished γ oscillation energy across the DLPFC-MPFC region. Previously, through the implementation of rTMS interventions on the left DLPFC, the investigators have successfully reduced the craving levels in users when exposed to relevant cues, coupled with observed decreases in β oscillation energy and increases in γ oscillation energy in the MPFC region. This indicates that both β and γ oscillation energies are instrumental in representing the involvement of MPFC and DLPFC during craving episodes, and neuromodulatory technologies can modulate these energy levels, consequently reducing cravings. Furthermore, the investigators identified a significant augmentation in the theta energy in the occipital lobe when MA dependents are confronted with drug-related cue imagery, signifying a potential crucial neural marker for addiction-induced brain activity. Therefore, the investigators intend to employ the non-invasive transcranial alternating current stimulation (tACS) technique, predicated upon biomarkers of addiction states, to administer specific frequency stimulations to targeted brain regions, aiming to achieve therapeutic objectives in addiction treatment.

Inclusion Criteria:

• Individuals aged between 18 and 45 years, irrespective of gender, having completed a minimum of 9 years of education and capable of effectively cooperating in questionnaire evaluations.
• Meet the diagnostic criteria set forth by the DSM-V concerning the severity of amphetamine-type substance addiction.
• A history of utilizing amphetamine-type substances for a duration not less than one year, with a frequency of use being at least once per week.
• Consent to actively cooperate in the completion of subsequent follow-up assessments.

Exclusion Criteria:

• Severe cognitive functional impairments manifested through a history of head trauma, cerebrovascular diseases, epilepsy, etc., or usage of cognitive enhancement drugs in the past 6 months; an intellectual disability with an IQ score less than 70.
• A diagnosis of schizophrenia or other severe mental illnesses as per the DSM-5 criteria.
• Abuse or dependence on other psychoactive substances (excluding nicotine) within the past 5 years.
• Severe organic diseases that might compromise study participation.
• Contraindications to tACS, such as a history of epileptic seizures or the presence of metallic implants in proximity to the head.