The goal of thisclinical trial is to investigate the efficacy of trans cranial direct current stimulation (tDCS) for alcohol craving in individuals with alcohol dependence. The main question it aims to answer is whether 10 sessions of tDCS can reduce craving for alcohol.

Participants will be randomized into active group and sham group. Researchers will compare the severity of craving in these groups.

Craving is defined as strong desire for substance use, and is one of the core symptoms of alcohol dependence which is highly correlated with relapse. Transcranial direct current stimulation (tDCS) involves applying a small direct current (1-2mA) to the prefrontal cortex; its therapeutic effect for depression and cognition has been demonstrated by several randomized studies. Our preliminary study has shown that tDCS has the potential to reduce craving in alcohol-dependent patients without adverse events. Furthermore, our previous studies have shown that serum brain-derived neurotrophic factor (BDNF) level is elevated after alcohol withdrawal. The current study aims at examining the association between craving and serum BDNF level in alcohol-dependent patients receiving tDCS. The study recruits 40 patients with alcohol dependence. Patients will receive tDCS for 2 weeks during admission, and followed for 2 weeks after tDCS. We'll compare their improvements in craving scores every week, and investigate the correlation between craving and serum BDNF level. This study will bring innovations to the treatment of alcohol dependence based on our previous studies.

Inclusion Criteria:

1. Be between 20-65 years of age
2. have sufficient cognitive function to understand the study and complete the informed consent process
3. Be diagnosed with alcohol dependence as defined by DSM-IV through a structured interview (Mini-International Neuropsychiatric Interview, M.I.N.I.)

Exclusion Criteria:

1. Intellectual disabilities
2. bipolar disorder
3. Psychosis (schizophrenia)
4. Major physical illness (brain hemorrhage, brain tumor, myocardial infarction, epilepsy or history of seizures)
5. intracorporeal electronic or metal implants (e.g., cardiac pacemaker)
6. Pregnant or breastfeeding women
7. Allergy to headgear and electrode materials
8. Trauma or infection to the head
9. Intracranial space occupied lesion (such as brain tumor, AVM, etc.) or patients who have undergone brain surgery, meningitis and encephalitis
10. Patients who are expected to undergo brain and major surgery during the trial period