Background
Methamphetamine (MA) use became ubiquitous as a recreational drug among adolescents and young adults in Thailand beginning in the mid-1990s [
1,
2]. The popularity of recreational MA use among Thai adolescents and young adults, the perceptions about MA use being normative or fashionable, exposure to MA from peers, personality traits such as curiosity and sensation-seeking, coping mechanisms and functional needs led to the emergence of MA as a significant public health problem among this population [
3,
4]. Indeed, MA use has a lasting psychosocial impact not only on individuals, but entire communities [
5]. MA became commonly referred by Thais as “ya-ba,” or crazy pill, due to its ability to induce psychosis and other psychological symptoms [
6]. By 2003, an estimated 3 million Thais or 5 % of the population were reported to be chronically dependent on MA [
7].
MA use has been shown to be associated with severe psychological harms and commonly is associated with depression [
8]. Studies in various settings have found a high prevalence of MA users reporting a lifetime history of depression, with prevalence estimates ranging between 50 % of men and 68 % of women and 57 % of MA users reporting the presence of depressive symptoms in the past year compared to 32 % among non-users [
9,
10]. Another study conducted among MA users entering treatment in Australia observed that 40 % (
n = 400) of study participants had a diagnosis of major depression within a year prior to admission, and another 44 % met the criteria for major depression but were excluded because their depressive symptoms were attributed to drug dependence [
11]. In a study of young Thai MA users aged 18–25 years, authors observed a prevalence of 35 % of participants presenting with high levels of depressive symptoms [
12]. Most studies are limited by design or methodology because they have assessed the prevalence of depression among amphetamine or MA users using various instruments to measure depressive symptoms, and most have examined limited data among health seeking populations that may not be representative of all users. Most of these studies have not been conducted among populations in low- and middle-income countries and only one was conducted among Thai youth. No studies of general Thai populations in rural areas have been conducted to our knowledge.
The nature of the relationship between depressive symptoms and MA use, abuse and dependence (i.e., drug-induced depressive symptoms, self-medicating to alleviate depressive symptoms, etc.) and the prevalence of these comorbid conditions have public health implications for treatment and prevention that have received little attention outside of the United States. Thailand, which is currently experiencing an MA epidemic, warrants further attention in terms of prevention and treatment of these comorbid conditions [
12]. Populations residing in Thailand’s Northern provinces, including Chiang Mai province, are the most accessible to MA trafficking routes since the drug is distributed across the borders separating Thailand from Laos and Burma, and many residents are involved in the drug trade [
7]. High levels of depressive symptoms may be greater than average among Thai adolescents and young adults in these rural areas within the Golden Triangle due to exposure to and participation in the MA market and the extensive use of MA within social networks. However, research has yielded little documentation of high levels of depressive symptoms comorbid to MA use in Thailand and little is known of evidenced-based or culturally-relevant interventions to prevent and treat both disorders. Furthermore, mental health and substance abuse research have received little attention in Thailand compared with the magnitude of publications dedicated to medical research [
13].
Our research attempts to add to the growing body of knowledge of mental health and substance use research emerging in Thailand using probabilistic sampling methods that improve the generalizability of results to the general population of adolescents and young adults in rural areas of northern Thailand where MA distribution and use is prominent. The primary purpose of this study is to describe the prevalence of depressive symptoms among MA users and to assess the association between MA use and depressive symptoms among Thais 14 – 29 years of age residing in rural areas of northern Thailand in close proximity to the Burma and Lao borders. We hypothesize that there will be an association between MA use and high levels of depressive symptoms.
Results
Descriptive statistics can be found in Table
1. The sample (
n = 2055) consisted predominately of young adults (
n = 1247) with a median age of 20 who were predominantly single, separated, widowed or divorced (79 %), of Thai ethnicity (100 %), and Buddhist (99 %) and reported living primarily at their parent’s house during the past 3 months (77 %), currently attending school (59 %), and currently being unemployed (56 %). Approximately 19 % reported ever having consumed MA (
n = 394) with 31 % of lifetime users reported recent MA use within the past 3 months (
n = 124). Relative to those without reported baseline lifetime MA use, individuals reporting ever having consumed MA were significantly more likely to be male (
p < 0.001).
Table 1
Characteristics of the Sample and CES-D Categories
Gender |
Males | 64 (35.2 %) | 987 (52.7 %) | 1051 (51.1 %) | <0.05 |
Age |
14–17 | 58 (31.9 %) | 750 (40.0 %) | 808 (39.3 %) | |
18–29 | 124 (68.1 %) | 1123 (60.0 %) | 1247 (60.7 %) | <0.05 |
Residence |
Parent’s house | 145 (79.7 %) | 1441 (76.9 %) | 1586 (77.2 %) | |
Other | 37 (20.3 %) | 432 (23.1 %) | 469 (22.8 %) | 0.401 |
Marital status |
Single, widowed, separated, divorced | 133 (73.1 %) | 1491 (79.6 %) | 1624 (79.0 %) | |
Currently married or cohabitating | 49 (26.9 %) | 382 (20.4 %) | 431 (21.0 %) | <0.05 |
Religion |
Buddhism | 181 (99.5 %) | 1850 (98.8 %) | 2031 (98.8 %) | ____ |
Ethnicity |
Thai | 182 (100 %) | 1871 (99.9 %) | 2053 (99.9 %) | ____ |
Current school attendance |
Yes | 89 (48.9 %) | 1123 (60.0 %) | 1212 (59 %)a
| <0.05 |
Employment status |
Full-time, part-time, irregular work | 88 (48.4 %) | 738 (41.0 %) | 817 (41.4 %)b
| 0.236 |
MA Use |
Lifetime use | 46 (25.3 %) | 348 (18.6 %) | 394 (19.2 %) | <0.05 |
Recent use | 20 (3.5 %) | 104 (29.9 %) | 124 (31.5 %)c
| <0.10 |
Illicit Substances |
Lifetime use | 41 (22.5 %) | 341 (18.2 %) | 382 (18.5 %) | 0.15 |
Recent Use | 5 (12.2 %) | 74 (21.7 %) | 79 (20.7 %)d
| 0.16 |
Alcohol Consumption |
Lifetime use | 131 (72.0 %) | 1370 (73.1 %) | 1501 (73.0 %) | 0.74 |
Recent use | 85 (64.9 %)e
| 858 (62.6 %) | 943 (62.8 %)e
| 0.61 |
Approximately 9 % of the sample (
N = 2055) met criteria for exhibiting high levels of depressive symptoms. The mean CES-D score estimated for the entire sample was 17.01 (S.D.: 6.39). The range of CES-D scores was 0–57. Among lifetime MA users, the prevalence of high levels of depressive symptoms was approximately 12 % (
n = 46) compared to 8 % of abstainers and 16 % among recent MA users compared to 10 % of abstainers. Relative to those who reported no lifetime MA use at baseline (Table
2), individuals who reported having ever used MA in their lifetime were more likely to have high levels of depressive symptoms using the recommended Thai cutoff score of ≥ 22 on the CES-D scale, but this measure of association did not reach statistical significance (POR: 1.48, CI: 1.04–2.11;
p <0.05). Of those who reported a history of lifetime MA use, recent MA users were almost twice as likely to have high levels of depressive symptoms compared to nonusers (POR: 1.80, CI: 0.96–3.38;
ρ <0.10). Compared to those without high levels of depressive symptoms, those defined as having high levels of depressive symptoms at baseline were more likely to be female (
p < 0.001). Table
1 also describes the distributions of high levels of depressive symptoms among various subgroups of the sample. Additionally, the proportion of female MA users having high levels of depressive symptoms was substantially higher than male MA users, with 23 % of females who reported ever using MA experiencing high levels of depressive symptoms compared to 9 % of males (
p < 0.01).
Table 2
Crude Prevalence Odds Ratios Indicating Odds of Endorsing High Levels of Depressive Symptoms among Demographic and Drug Use Behavior Characteristics
Age | 1.43 | 1.03–1.98 | <0.05 |
Gender | 2.05 | 1.50–2.82 | <0.001 |
Highest level of educationa
| 0.93 | 0.66–1.33 | 0.71 |
Current school attendance | 1.57 | 1.15–2.13 | <0.05 |
Employedb
| 1.21 | 0.88–1.65 | 0.24 |
Residence | 0.93 | 0.66–1.33 | 0.71 |
Lifetime MA use | 1.48 | 1.04–2.11 | <0.05 |
Recent MA usec
| 1.80 | 0.96–3.38 | <0.10 |
Lifetime polydrug use | 1.31 | 0.91–1.89 | 0.15 |
Recent polydrug used
| 0.50 | 0.19–1.32 | 0.16 |
Lifetime alcohol consumption | 0.94 | 0.67–1.32 | 0.74 |
Recent Alcohol consumptione
| 1.10 | 0.76–1.60 | 0.61 |
We examined demographic and behavioral variables identified in the literature as confounders. In our study, associations between high levels of depressive symptoms and age, gender and current school attendance were statistically significant (Table
2). In other words, the odds of having a high level of depressive symptoms was greater among females, young adults, individuals not currently attending school, and MA users. Due to concerns about collinearity, we used current school attendance in the final model rather than educational attainment. Multivariate logistic regression (Table
3) demonstrated significant, independent associations between recent MA use and high levels of depressive symptoms (POR: 2.60, 95 % CI: 1.20, 5.63). Statistical models which accounted for clustering by using the “xtlogit” command in Stata generated similar prevalence odds ratios (data not shown) and there was no evidence for effect modification of high levels of depressive symptoms by MA use and polydrug use or by MA use and gender.
Table 3
Adjusted prevalence ratios derived from logistic regression for high levels of depressive symptoms, MA use and covariates to describe odds of high levels of depressive symptoms among adolescents and young adults who use MA in northern rural Thailand
Lifetime MA Risk Behavior (N = 2054) |
Lifetime MA use | 1.61 | 0.98–2.64 | 0.06 |
Lifetime polydrug use N = 2054 | 1.45 | 0.87–2.43 | 0.16 |
Lifetime alcohol consumption | 0.82 | 0.55–1.23 | 0.33 |
Gender | 2.63 | 1.82–3.80 | <0.001 |
Age | 1.16 | 0.75–1.77 | 0.49 |
Current school attendance | 1.35 | 0.92–1.99 | 0.13 |
Recent MA Risk Behavior (n = 266) |
Recent MA use | 2.60 | 1.20–5.63 | <0.05 |
Recent polydrug use | 0.53 | 0.17–1.67 | 0.23 |
Recent alcohol consumption | 0.85 | 0.26–2.75 | 0.79 |
Gender | 3.31 | 1.28–8.55 | <0.05 |
Age | 0.93 | 0.30–2.87 | 0.90 |
Current school attendance | 1.19 | 0.43–3.33 | 0.74 |
Discussion
High levels of depressive symptoms were associated with reported recent MA use. This study quantifies the prevalence of high levels of depressive symptoms comparing MA users to non-MA users in a general population of adolescent and young Thai adults. The study also examines the association between depressive symptoms and MA among Thai youth living in rural areas using a complex sampling strategy consisting of multistage, community-clustered and systematic random sampling. Such a study sampling method was necessary given the ubiquity of MA trafficking and distribution in this region. Consistent with our hypothesis, high levels of depressive symptoms were positively associated with MA use.
We observed high rates of depressive symptoms in the entire sample and among MA users. In our study, approximately 12 % of individuals who reported ever using methamphetamine had high levels of depressive symptoms. The prevalence of depression among MA users is comparable with the estimates reported among psychostimulant users in the U.S. [
23]. There are several possible explanations for observing this association. First, this population could possibly be suffering psychological sequelae of chronic MA use. Second, adolescents and young adults could initiate MA use as an attempt to self-medicate an existing depression [
24]. The historical, social, economic and political context existing within Thailand is such that there is a change to a more competitive, global market-driven economy from a rural, agrarian lifestyle. This new social and political environment is replacing traditional family values, and these changes may initiate the onset of stress and lead to the development of depression among youth who perceive they are responsible for competing in the global economy [
4]. Moreover, in a region where the drug market renders MA to be widespread, accessible and inexpensive, economic stressors may lead to the onset of depression and subsequently lead to MA use by adolescents and young adults to self-medicate [
25].
The relationship between MA and depression could potentially be bidirectional. Symptoms indicative of depression could lead to initiation and continuation of MA use. Consequently, affective and motivational dysfunction related to depression can occur as a result of chronic use and withdrawal, which could possibly contribute to the continuation of MA use for the maintenance of depressive symptoms. This maintenance of depressive symptoms is prolonged due to sustained use of drugs in greater amounts, more frequent use or injecting in order to relieve depressive symptoms resulting from chronic use [
26]. One longitudinal epidemiological study attempted to address the nature of this relationship by assessing the temporality of MA use and depressive symptoms among MA users in Thailand. This study concluded that depressive symptoms were a consequence of MA use [
12].
Of note is the observed independent crude and adjusted association between gender and high levels of depressive symptoms. Of the participants that endorsed high levels of depressive symptoms, 6 % were male compared to 12 % of females. On the other hand, approximately 33 % of males reported recent MA use compared to 23 % of females and explains the lack of effect modification by gender. We had hypothesized a priori that gender would be a confounder since previous literature has documented higher levels of depressive symptoms in females, whether induced by substance use or independent of substance use, and has documented that males are more likely to use illicit substances than females. Other covariates were added to the multivariate model if they met the aforementioned criteria for being included, but had little effect on the estimate describing MA use and high levels of depressive symptoms.
Treatment of depressive symptoms presenting with substance use and dependence of MA has been problematic. Several randomized controlled trials conducted to evaluate the efficacy of various antidepressants in relieving depressive symptoms and achieving cessation have found treatment to be inconsistently efficacious among individuals who were dependent on or abused MA or cocaine [
27‐
30]. All of these trials have been conducted in urban areas of the United States, and most involve small sample sizes. An additional review of treatment options specific to MA users presenting with depression reveals a large gap in knowledge of effective, sustainable treatment options whether treatment options are psychological approaches, pharmacological approaches or both [
31].
There are some limitations inherent in this study that must be considered. First, the study was cross-sectional. A temporal relationship between MA use and high levels of depressive symptoms cannot be established. Second, there could be underreporting of stigmatized behaviors and stigmatization of MA use by Thai communities remains a concern among youth [
3]. Misclassification could result from self-reports, but our interviews were administered using Audio computer-assisted self-interview (ACASI) software where previous studies have shown little effect on internal validity in similar populations [
32]. Another limitation that should be considered is that the parent study was not implemented solely to assess our hypothesis. Therefore, numerous possible other (unmeasured) confounders such as other psychiatric disorders were not included in the survey. However, such disorders would be rare in this population. Different time frames were used to measure recent MA use, polydrug use and alcohol consumption. We did not include measures of illicit drug polydrug or MA use within the past 30 days in our baseline survey. However, inferences about the independent association between high levels of depressive symptoms and recent MA use within the past 3 months were similar in our univariate and multivariate models when recent polydrug and alcohol use were incorporated into the model and the association supports previous findings. Last, the Thai cutoff of ≥ 22 was based on research among a limited sample size and included only Thai adolescent males.
This study presents strengths relevant for drawing public health implications. The large sample size of the study population, the probabilistic sampling methodology, and the extensive coverage of several communities within sub-districts are strong characteristics of this study. Relatively little research has been conducted in Thailand that quantifies the prevalence of high levels of depressive symptoms among adolescents and young adults who use MA, either in clinical samples or the general population. Little mental health or substance abuse research, in general, has been conducted in Thailand, but recent efforts to address these knowledge gaps are leading to a burgeoning field of substance use and mental health research in Thailand, and this study contributes to that research base. Most notably, an assessment of Thailand’s mental health care services by the Thai Ministry of Health and the World Health Organization specified that only 1 % of health-related research published in peer reviewed journals in Thailand is mental health research [
13]. To our knowledge, no assessments of the prevalence and associations between high levels of depressive symptoms and MA use have been conducted in rural Chiang Mai province, the epicenter of an existing MA epidemic. There is a known association between MA use and depression, but few resources for the treatment and prevention of depression and substance use exist in this rural region. These assessments of individual-level risk factors that are associated with high levels of depressive symptoms provide information that could be used to target prevention efforts among Thai youth who use MA in this region.
Additional longitudinal and qualitative studies should be conducted to examine how other individual-level factors and multiple-level factors (i.e. physical environment, social context, substance use, abuse and dependence) predict the onset of depressive symptoms among Thai youth to better understand the individual-level and structural factors driving the onset of depression. Longitudinal studies should also be designed to assess if depressive symptoms precede or are a consequence of substance use.
Generally, this study could be used as the basis to begin the evaluation of the effectiveness of treatment and prevention interventions for depressive symptoms associated with MA use in Thailand as well as other low- and middle-income countries. The positive association seen in our study suggests that accessible and culturally acceptable mental health care services should be integrated with drug treatment programs among drug-dependent youth. The results also indicated that policies aimed at maximizing resources in rural Thailand to deliver more humane and evidence-based approaches to care and treatment of depressive symptoms among MA users could contribute to the prevention of MA use and the reduction of depressive symptoms among Thai youth.
Competing interests
The authors declare that they have no financial or non-financial interests to declare.
Authors’ contributions
LD, DC and SS conceived the study and contributed to interpretation of the data. LD designed the study, drafted the manuscript and analyzed the data. AA and BS contributed to the acquisition of data, and interpretation of the data. All authors made substantial contributions to the revision of the manuscript. All authors have given final approval for publication of this version of the manuscript.