Add-on Low Dose Dextromethorphan and Memantine in Patients With Amphetamine-type Stimulants Use Disorder

The urinary amphetamine tests will be examined during the 12 weeks of treatment period in patients with ATSUD and the results will be compared between the experimental and placebo groups.

The Visual analog scale (VAS) will be measured during the 12 weeks of treatment period in patients with ATSUD. The results will be compared between the experimental and placebo groups. The level of conscious craving was rated from 0 (none) to 100 (very much). Higher scores indicate more severe craving.

The investigators will use the self-reported questionnaire, side effects checklists, to evaluate the side effects during the 12 weeks of treatment period in patients with ATSUD. The side effects assessment includes, A) Mental Status/6-item, B) Genito-Urinary/4-item, C) Cardiovascular/4-item, D) Head-Neck/10-item, E) Extremities/9-item, F) Skin/4-item, and G) Gastrointestinal Tract/2-item. The severity of side effects were divided into 4 degrees as follows: 0 = Not present; 1 = Mild or occasional; 2 = Moderate or occurs several times a day; and 3 = Severe or persistent. Scores in each subscale will be summated to get the final total scores. Higher scores indicate more severe side effects. The results of side effects checklists will be compared between the experimental and placebo group.

The Wisconsin Card Sorting Test (WCST) will be measured in patients with ATSUD at the initial screen period and at the endpoint (after 12 weeks of treatment). We will compare the changes from screen period to the endpoint between experimental and placebo group. Performance on the WCST was scored in terms of the total number of errors (TNE, range form 0-128), perseverative errors (PE, range from 0-118), conceptual level responses (CLRs, range from 0-100%), number of categories completed (NCC, range form 0-12), and trials to complete the first category (TCC, range from 0-128). Higher scores indicate worse performance in TNE, PE, and TCC. Higher scores indicate better performance in CLRs and NCC.

The Continuous performance tests (CPT) will be measured in patients with ATSUD at the initial screen period and at the endpoint (after 12 weeks of treatment). We will compare the changes from screen period to the endpoint between experimental and placebo group. The CPT produces a standard set of performance measures that include the number of errors of omission and errors of commission. (1) Errors of omission occur when the participant fails to respond to the target stimulus. The omission errors t-scores are ranged from 20-80 (0-100%). Higher scores indicated worse performance. (2) Errors of commission occur when the participant responds to a non-target (X) stimulus. The commission errors t-scores are ranged from 20-80 (0-100%). Higher scores indicated worse performance.

The Wechsler Memory Scale - third edition (WMS-III) will be measured in patients with ATSUD at the initial screen period and at the endpoint (after 12 weeks of treatment). We will compare the changes from screen period to the endpoint between experimental and placebo group. WMS-III composite scores were calculated for the eight standardized primary indices: Auditory Immediate (AIM, range from 50-156), Visual Immediate (VIM, range from 47-162 ), Immediate Memory (IM, range from 40-164 ), Auditory Delayed (ADM, range from 46-162), Visual Delayed (VDM, range from 43-156), Auditory Recognition Delayed (ARDM, range from 55-145), General Memory (GM, range from 40-168), and Working Memory (WM, range from 45-156 ). Higher scores indicate better performance.

The plasma levels of cytokines and neurotrophic factors, tumor necrosis factor α (TNF-α[pg/mL]), transforming growth factor β1 (TGF-β1 [pg/mL]), interleukin 6( IL-6[pg/mL]), interleukin 8(IL-8[pg/mL]), interleukin 1β (IL-1β[pg/mL]), and brain-derived neurotrophic factor(BDNF[pg/mL]), will be measured in patients with ATSUD at the initial screen period, day 1(baseline), week 4, 8, and 12(endpoint). We will compare the changes from screen period to the endpoint between the experimental and placebo group.

The plasma levels of C-reactive protein (CRP[μg/mL]) will be measured in patients with ATSUD at the initial screen period, day 1(baseline), week 4, 8, and 12(endpoint). We will compare the changes from screen period to the endpoint between the experimental and placebo group.