This study examined the association between methamphetamine use and psychotic symptoms in a New Zealand general population birth cohort (n = 1265 at birth).

At age 18, 21, 25, 30, and 35, participants reported on their methamphetamine use and psychotic symptoms in the period since the previous interview. Generalized estimating equations modelled the association between methamphetamine use and psychotic symptoms (percentage reporting any symptom, and number of symptoms per participant). Confounding factors included childhood individual characteristics, family socioeconomic circumstances and family functioning. Long term effects of methamphetamine use on psychotic symptoms were assessed by comparing the incidence of psychotic symptoms at age 30–35 for those with and without a history of methamphetamine use prior to age 30.

After adjusting for confounding factors and time-varying covariate factors including concurrent cannabis use, methamphetamine use was associated with a modest increase in psychosis risk over five waves of data (adjusted odds ratio (OR) 1.33, 95% confidence interval (CI) 1.03–1.72 for the percentage measure; and IRR 1.24, 95% CI 1.02–1.50 for the symptom count measure). The increased risk of psychotic symptoms was concentrated among participants who had used at least weekly at any point (adjusted OR 2.85, 95% CI 1.21–6.69). Use of methamphetamine less than weekly was not associated with increased psychosis risk. We found no evidence for a persistent vulnerability to psychosis in the absence of continuing methamphetamine use.

Methamphetamine use is associated with increased risk of psychotic symptoms in the general population. Increased risk is chiefly confined to people who ever used regularly (at least weekly), and recently.

这项研究调查了新西兰一般人口出生队列（出生时n = 1265）中甲基苯丙胺使用与精神病症状之间的关联。

在 18 岁、21 岁​​、25 岁、30 岁和 35 岁时，参与者报告了自上次采访以来他们的甲基苯丙胺使用情况和精神病症状。广义估计方程模拟了甲基苯丙胺使用与精神病症状之间的关联（报告任何症状的百分比，以及每个参与者的症状数量）。混杂因素包括童年个体特征、家庭社会经济环境和家庭功能。通过比较 30 岁之前有和没有甲基苯丙胺使用史的人在 30-35 岁时精神病症状的发生率，评估了甲基苯丙胺使用对精神病症状的长期影响。

在调整混杂因素和时变协变量因素（包括同时使用大麻）后，甲基苯丙胺的使用与五波数据中精神病风险的适度增加有关（调整后的比值比 (OR) 1.33，95% 置信区间 (CI) 1.03–百分比测量为 1.72；症状计数测量的 IRR 为 1.24，95% CI 1.02–1.50）。精神病症状的风险增加集中在至少每周使用一次的参与者中（调整后的 OR 2.85，95% CI 1.21–6.69）。少于每周使用甲基苯丙胺与精神病风险增加无关。我们没有发现在没有持续使用甲基苯丙胺的情况下持续易患精神病的证据。

甲基苯丙胺的使用与一般人群中精神病症状的风险增加有关。增加的风险主要局限于曾经定期（至少每周）和最近使用过的人。