Research ArticleNEUROSCIENCE

Time perception deficits and its dose-dependent effect in methamphetamine dependents with short-term abstinence

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Science Advances  30 Oct 2019:
Vol. 5, no. 10, eaax6916
DOI: 10.1126/sciadv.aax6916
  • Fig. 1 Temporal reproduction task and findings of experiment 1.

    (A) All participants needed to complete a temporal reproduction task where the duration of the gray oval (1 to 5 s) in the encoding phase should be remembered in people’s mind. Then, when the duration of the gray oval displayed in the reproduction phase matched the encoding one, participants were asked to press the space bar. ISI, interstimulus interval; ITI, intertrial interval. (B) For the meth-long group and HCs, the duration reproduction ratio (DRR) was higher than 1 at durations of 1 and 2 s, lower than 1 at durations of 4 and 5 s, but not different from 1 at duration of 3 s. For the meth-short group, the indifferent time point dropped at 2 s. The dotted line indicates accurate reproduction. ns, not significant, #P = 0.051, *P < 0.05, **P < 0.01, ***P < 0.001. Error bars represent SEM. (C) HCs showed a higher coefficient of variation (CV) than the two meth groups across all target durations. Error bars represent SEM. (D to H) When the target duration was longer than 1 s, there was a significant negative correlation between the DRR and dosage of meth use before abstinence in the meth-short group. This pattern did not exhibit in the meth-long group. *P < 0.05. (I to M) When the target duration was longer than 2 s, there was a significant positive correlation between the CV and dosage of meth use before abstinence in the meth-short group. This pattern did not exhibit in the meth-long group. *P < 0.05.

  • Fig. 2 Temporal discrimination task (subsecond) and findings of experiment 2a.

    (A) In the task, a gray oval with the standard duration (500 ms) appeared first, and then a comparison duration (200, 350, 500, 650, or 800 ms) was shown. Participants indicated whether the comparison was longer or shorter than the standard when an exclamation mark was displayed. (B) Mean proportion of “long” responses in each comparison duration was fitted a logistic function for HCs (gray) and the meth-short group (purple), respectively. The dotted line represents 50% of “long” responses. (C) Both HCs (gray) and the meth-short group (purple) did not overestimate or underestimate the subsecond duration. The group difference was not significant. The dotted line represents the standard duration (500 ms). (D) There was no significant group difference in the slope of the curve. (E) The relationship between the dosage of meth use before abstinence and PSE was not significant (r = −0.026, P = 0.881). (F) The relationship between the dosage of meth use before abstinence and slope was not significant (r = −0.125, P = 0.475).

  • Fig. 3 Temporal discrimination task (suprasecond) and findings of experiment 2b.

    (A) In the task, a gray oval with the standard duration (2000 ms) appeared first, and then a comparison duration (1400, 1700, 2000, 2300, or 2600 ms) was shown. Participants indicated whether the comparison was longer or shorter than the standard when an exclamation mark was displayed. (B) Mean proportion of “long” responses in each comparison duration was fitted a logistic function for HCs (gray) and the meth-short group (purple), respectively. The dotted line represents 50% of “long” responses. (C) Both HCs (gray) and the meth-short group (purple) overestimated the suprasecond duration, but the group difference was not significant. The dotted line represents the standard duration (2000 ms). ***P < 0.001. (D) There was no significant group difference for the slope of the curve. (E) The negative relationship between the dosage of meth use before abstinence and PSE was significant (r = −0.507, P = 0.004). (F) The relationship between the dosage of meth use before abstinence and slope was not significant (r = 0.221, P = 0.241).

  • Table 1 Demographic characteristics of the HC, MS, and ML groups in experiment 1 (mean ± SD).

    BAI, Beck Anxiety Inventory; BDI, Beck Depression Inventory; PSQI, Pittsburgh Sleep Quality Index; BIS, Barratt Impulsivity Scale; NA, not applicable.

    HC
    (n = 54)
    MS
    (n = 53)
    ML
    (n = 50)
    Statistics
    (F or t)
    PEffect size
    2p or Cohen’s d)
    Post hoc test*
    Age (years)36.02 ± 11.9337.34 ± 7.1736.40 ± 8.670.2740.7600.004NA
    Education (years)9.80 ± 2.459.05 ± 3.668.68 ± 2.911.8290.1640.023NA
    BAI26.19 ± 7.2529.06 ± 10.5426.94 ± 7.431.6100.2030.020NA
    BDI7.81 ± 6.9916.34 ± 10.9214.00 ± 9.2212.329<0.0010.138MS > HC, ML > HC
    PSQI4.15 ± 2.556.98 ± 3.976.76 ± 3.7910.884<0.0010.124MS > HC, ML > HC
    BIS-1169.85 ± 19.2783.47 ± 19.2983.54 ± 18.229.197<0.0010.107MS > HC, ML > HC
    Duration of current abstinence (months)NA3.00 ± 1.8616.30 ± 6.28−14.384<0.0012.872NA
    Years of meth use before abstinenceNA8.41 ± 4.797.95 ± 4.520.4960.6210.099NA
    Dosage of meth use before abstinence (g/month)NA13.40 ± 14.9619.46 ± 13.52−2.1550.0340.425NA

    *The greater than symbol indicates direction of the significant results.

    • Table 2 Demographic characteristics of the HC and MS groups in experiment 2a (mean ± SD).

      HC
      (n = 43)
      MS
      (n = 35)
      tPEffect size
      (Cohen’s d)
      Age (years)34.60 ± 8.9735.34 ± 7.36−0.3910.6970.090
      Education (years)9.67 ± 1.578.69 ± 3.221.6610.1030.387
      BAI26.70 ± 7.0528.79 ± 7.73−1.2410.2180.283
      BDI12.00 ± 9.6416.26 ± 8.27−2.0500.0440.474
      PSQI5.65 ± 3.226.40 ± 3.16−1.0290.3070.235
      BIS-1176.35 ± 18.5687.76 ± 18.25−2.7060.0090.620
      Duration of current abstinence (days)NA69.74 ± 35.95NANANA
      Years of meth use before abstinenceNA7.69 ± 3.78NANANA
      Dosage of meth use before abstinence (g/month)NA14.04 ± 13.47NANANA
    • Table 3 Demographic characteristics of the HC and MS groups in experiment 2b (mean ± SD).

      HC
      (n = 37)
      MS
      (n = 30)
      tPEffect size
      (Cohen’s d)
      Age (years)33.19 ± 6.3934.90 ± 7.06−1.0400.3020.254
      Education (years)10.32 ± 1.899.53 ± 2.441.5360.1290.362
      BAI25.81 ± 6.2427.66 ± 5.61−1.2460.2170.312
      BDI9.24 ± 7.6416.93 ± 9.08−3.765<0.0010.916
      PSQI5.08 ± 2.446.90 ± 3.00−2.7370.0080.666
      BIS-1174.81 ± 21.2585.76 ± 16.13−2.3020.0250.580
      Duration of current abstinence (days)NA58.83 ± 17.51*NANANA
      Years of meth use before abstinenceNA7.07 ± 4.06NANANA
      Dosage of meth use before abstinence (g/month)NA15.24 ± 11.48NANANA

      *Because of the technical fault, only 18 meth abusers were recorded, but the duration of abstinence of others was around 3 months.

      Supplementary Materials

      • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/10/eaax6916/DC1

        Fig. S1. Consort flow diagram for experiment 1.

        Fig. S2. Consort flow diagram for experiment 2a.

        Fig. S3. Consort flow diagram for experiment 2b.

        Table S1. Pearson’s correlations between behavioral indices of experiment 1 and dosage of meth use before abstinence (g/month), r (P value).

        Table S2. Pearson’s correlations between behavioral indices of experiment 2a and some demographic characteristics, r (P value).

        Table S3. Pearson’s correlations between behavioral indices of experiment 2b and some demographic characteristics, r (P value).

      • Supplementary Materials

        This PDF file includes:

        • Fig. S1. Consort flow diagram for experiment 1.
        • Fig. S2. Consort flow diagram for experiment 2a.
        • Fig. S3. Consort flow diagram for experiment 2b.
        • Table S1. Pearson’s correlations between behavioral indices of experiment 1 and dosage of meth use before abstinence (g/month), r (P value).
        • Table S2. Pearson’s correlations between behavioral indices of experiment 2a and some demographic characteristics, r (P value).
        • Table S3. Pearson’s correlations between behavioral indices of experiment 2b and some demographic characteristics, r (P value).

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