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Abstract Methamphetamine (MAP) abuse has been common in Taiwan for the past decade. The purpose of the present study was to investigate MAP abuse in Taiwan, with specific attention to psychiatric comorbidity and gender differences. A total of 325 MAP abuse subjects (180 male, 145 female) from a detention center in Taipei were assessed with the Diagnostic Interview for Genetic Studies. The following were studied: drug use behavior, treatment-seeking behavior, lifetime prevalence of mood disorders, MAP psychosis, alcohol use disorders, pathological gambling and antisocial personality. The MAP-abuse subjects in Taiwan had high psychiatric morbidity and low access to mental health services. There also exist certain differences in the prevalence of psychiatric illnesses and treatment-seeking behavior between male and female subjects. Compared with their male counterparts, more female subjects reported experience of mental disturbance and experience of psychiatric treatment. The female subjects more commonly reported suicidal behaviors than the male subjects.
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Methamphetamine (MAP), a derivative of amphetamine, has similar psychotropic properties but more pronounced effects on the central nervous system than amphetamine.1 The use of MAP has become increasingly widespread both in the Western world and in Asia. The incidence and prevalence of MAP abuse in Taiwan has increased dramatically. For example, since 1990 more than 20 000 people have been reported for MAP abuse each year. Approximately 20 years ago, glue sniffing was the most common form of substance abuse among adolescents in Taiwan, but in the last 10 years a MAP epidemic has beset Taiwanese youth. Among adolescent students, the prevalence of illicit substance use was 1.5% in 1996, and the most commonly abused illicit substance was MAP (43.1%).2
Persons with drug use disorders commonly experience other mental disorders and rates for comorbidity of 53% have been reported.3 For substance abuse, particularly common comorbid psychiatric disorders are major depressive disorder, alcoholism and antisocial personality.4 Comorbidity of psychotic disorder and substance abuse is also common.3,5,6 Incidence of schizophrenia has been observed at rates greater than that of the general population in individuals with a primary diagnosis of substance abuse,7 and occurrence of organic psychosis in this population has been reported at rates as high as 33%.8 Chen et al. studied the psychiatric comorbidity among hospital and incarcerated male heroin addicts in Taiwan and concluded that prevalent coexisting axis I disorders are additional substance use disorders and mood disorders, while antisocial personality disorder is the most significant axis II diagnosis.9 So far, little is known about the mental health of the persons abusing amphetamine in Taiwan, particularly those incarcerated or those in the community.
For many years, women were perceived as not suffering from substance abuse problems to the same extent as men, and many of the studies of both alcoholism and drug abuse were conducted using male subjects. In the Epidemiologic Catchment Area study, conducted in the early 1980s, the 1 month prevalence rates of drug use disorders of men were twofold or threefold higher than that of women.3 However, more recent studies showed that the gender differential is smaller than what is expected. The National Comorbidity Study reported that the lifetime prevalence of drug dependence is 9.2% for men and 5.9% for women.10 The National Household Survey on Drug Abuse revealed that the lifetime illicit drug use in women is approximately 30% whereas that in men is 40%.11 Differences between men and women in many aspects (e.g. etiological consideration and psychiatric comorbidity) of substance use disorders have received increasing attention over the past decade.
Studies of comorbid psychiatric disorders in opiate abuse found a higher percentage of affective and anxiety disorders in women than in men.12 In a study of cocaine abuse, Rounsaville et al. found a nearly equal gender distribution of affective disorder (43% for men, 47% for women) but nearly twice the prevalence of anxiety disorder in women compared with men.13 Personality disorder, particularly antisocial social personality disorder is more common in male than in female cocaine abuse subjects.13,14 To date, there has been no report investigating the gender differences in the psychiatric comorbidity for MAP abuse. The present study investigated the gender differences for MAP abuse in Taiwan, with specific attention to psychiatric comorbidity.
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Patients were drawn from a protocol for the study of predisposing factors to MAP-induced psychosis.15 This subsample was recruited from a detention center in Taipei, Taiwan, where men and women are detained in different houses. The subjects were recruited using systematic sampling: the first available MAP-use subject in the room waiting for an evaluation of their addiction severity was approached. The initial eligibility criteria for either sample were (i) to be aged more than 17 years; (ii) to be of ethnic Chinese origin; and (iii) to have used MAP >20 times during a 1 year period. The latter criterion excluded opportunistic (never) MAP-use subjects. Those who had a history of psychosis prior to MAP use and those for whom psychosis was closely related to other psychedelic drugs were also excluded.
Because use of amphetamines is illegal in Taiwan, the researchers emphasized to the subjects that their legal status would not be affected by participation in the study. The eligible subjects, after giving informed consent, underwent a diagnostic interview with selected sections from the Chinese version of Diagnostic Interview for Genetic Studies (DIGS-C).16 The Diagnostic Interview for Genetic Studies (DIGS) includes a detailed assessment of the longitudinal course of illness, with particular attention to the comorbidity of substance abuse and psychotic and mood symptoms.17 In the original version of the DIGS, the marijuana section was separated from the general drug section. In the present study, the questionnaire was modified to focus more on MAP use.
Each DIGS-C interview record was reviewed by a senior psychiatrist so that diagnoses of MAP-related disorders and psychiatric disorders according to the Diagnostic and Statistical Manual of Mental Disorders (4th edn, DSM-IV)18 criteria could be made. Comorbid psychiatric disorders ascertained in the present study included MAP-induced psychotic disorder, mood disorders, alcohol use disorders, pathological gambling and antisocial personality. The diagnosis of major depression was made only when at least one major depression episode occurred before first MAP use, and was not caused by other organic factors. An episode that met the criteria for major depression but occurred exclusively during MAP use or after MAP withdrawal was considered as MAP-related. For the diagnosis of antisocial personality disorder to be given, the individual had to be at least 18 years of age and must have had a history conduct disorder before age 15 years.
Interrater reliability (kappa) for MAP psychosis, mood disorders, alcohol use disorders, pathological gambling, and antisocial personality were 0.92, 0.67, 0.73, 0.67, and 0.84, respectively. Analyses were conducted using spss (SPSS, Chicago, IL, USA). The statistics used for univariate analysis in the present study included Pearson χ2 tests and Fisher's exact tests for categorical variables, whereas the Mann–Whitney U-test was used for continuous variables. Most of the continuous variables in the present study, including age, education, amount and duration of MAP use, were not normally distributed.
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Of the 325 MAP-use subjects, there were 180 men and 145 women. The gender ratio in the present study did not reflect that of the general population of persons using MAP in Taiwan. The subjects from the detention center were recruited from a male house and a female house separately, resulting in a more balanced distribution of men and women. The age distribution had a marked positive skew. Table 1 shows the comparisons of demographic characteristics between the male and female MAP-abuse subjects. The mean age of the subjects were 28.0 years for men and 25.3 years for women. Generally the subjects in the present study were not highly educated. The mean years of education was slightly more than the 9 years of obligatory education in Taiwan. More than 80% of the subjects were either single, divorced, separated or widowed. Crime other than illicit drug use was common among these MAP-abuse subjects, and significantly more common among men than women (54.8% vs 25.9%).
Table 1. Comparison of patient details and gender in methamphetamine abuse
| ||Male n = 180||Female n = 145||Total n = 325||Significance test|
|Age (years)|| || || ||Z = 4.3|
| Mean ± SD||28.0 ± 7.0||25.3 ± 6.7||26.8 ± 7.0||P < 0.001†|
| 18–27 (%)||104 (57.8)||112 (77.2)||216 (66.5)||χ2 = 13.7, d.f. = 2|
| 28–37 (%)|| 56 (31.1)|| 25 (17.2)|| 81 (24.9)||P = 0.001‡|
| >37 (%)|| 20 (11.1)|| 8 (5.5)|| 28 (8.6)|| |
|Education (years)|| || || ||Z = 2.2|
| Mean ± SD|| 9.2 ± 2.1|| 9.2 ± 2.3|| 9.2 ± 2.2||P = 0.829†|
|Marital status|| || || ||χ2 = 12.8, d.f. = 2|
| Married (%)|| 27 (15.0)|| 30 (20.7)|| 57 (17.5)||P = 0.002‡|
| Never married (%)||133 (73.9)|| 81 (55.9)||214 (65.8)|| |
| Divorced/separated/widowed (%)|| 20 (11.1)|| 34 (23.4)|| 66 (16.6)|| |
|Employment|| || || ||χ2 = 31.6, d.f. = 1|
| Employed (%)||171 (97.2)||111 (76.6)||282 (87.9)||P < 0.001‡|
| Unemployed (%)|| 5 (2.8)|| 34 (23.4)|| 94 (12.1)|| |
|Crime|| || || ||χ2 = 25.6, d.f. = 1|
| No (%)|| 76 (45.2)||100 (74.1)||176 (58.1)||P < 0.001‡|
| Yes (%)|| 92 (54.8)|| 35 (25.9)||127 (41.9)|| |
In cases of MAP abuse in Taiwan it is used in a crystal form. In some cases MAP is put on a piece of tin foil, heated underneath, then inhaled as smoke, or, more commonly, an ‘inhaling ball’ ball is used. This is a device made of glass used to inhale MAP in a more efficient way. The age of first MAP use ranged from 12 to 48 years, with a mean of 21.6 ± 6.9 years. The average weekly consumption of MAP ranged from 0.1 g to 21 g, with a mean of 1.6 ± 2.6 g. The mean duration of MAP abuse was 26.5 ± 25.0 months. The comparisons of MAP use patterns between male and female subjects are shown in Table 2. The women were significantly younger at first MAP use (Z = 2.9, P = 0.003). There was no significant difference in duration or weekly consumption of MAP abuse between the male and female subjects. The most commonly misused drugs in the subjects were sedatives and opiates (mainly heroin). Compared to men, more women had misused sedatives (χ2 = 12.7, d.f. = 1, P < 0.001).
Table 2. Comparison of drug use patterns and gender in methamphetamine abuse
| ||Male (n = 180)||Female (n = 145)||Significance test|
|Methamphetamine use||Mean ± SD||Mean ± SD||Z||P|
|Age at first use (years)||22.7 ± 7.5||20.3 ± 5.8|| 3.0|| 0.003|
|Amount (g/week)|| 1.6 ± 2.6|| 1.7 ± 2.6|| 0.3|| 0.761|
|Duration (months)||25.4 ± 22.7||27.8 ± 27.6|| 0.4|| 0.684|
|Other drug use†||n (%)||n (%)||χ2 (d.f)||P|
| Sedatives||11 (6.3)||28 (19.3)||13.2 (1)||<0.001|
| Opiates|| 9 (5.1)||7 (4.8)|| 0.005 (1)|| 0.943|
| Marijuana|| 2 (1.1)||1 (0.7)||–||–|
| Solvents||0||2 (1.4)||–||–|
| Cocaine||0||1 (0.7)||–||–|
Only 28 MAP abuse subjects (8.9%) had visited mental health professionals and only 10 (3.1%) had been admitted to a psychiatric facility, although 36.6% of them reported experience of mental disturbance and 24.3% reported occupational impairment. Table 3 details the experiences of mental problems or treatments due to usage of MAP as reported by the subjects. Compared to men, women more frequently reported being mentally disturbed, occupationally impaired, and seeking treatment.
Table 3. Overview of psychiatric disturbance among persons incarcerated for methamphetamine abuse
| ||Male n = 180 (%)||Female n = 145 (%)||Total n = 325 (%)|
|Suffered from psychiatric problems*||56 (31.1)||63 (43.4)||119 (36.7)|
|Sought professional help for psychiatric problems*|| 9 (5.1)||20 (13.8)|| 29 (8.9)|
|Experienced occupational impairment*||31 (17.3)||48 (33.1)|| 79 (24.3)|
|Took medications for psychiatric problems*||11 (6.2)||28 (19.4)|| 39 (12.0)|
|Been hospitalized for psychiatric problems*|| 3 (2.7)|| 7 (7.4)|| 10 (3.1)|
|Felt the need to seek professional help*||18 (10.9)||35 (26.3)|| 53 (16.3)|
Seventy-two MAP abuse subjects (22.1%) met criteria for past MAP-induced psychotic disorder. Three of them (4.2%) had psychosis for more than 1 month after stopping MAP use. The rates of major depression, alcohol dependence, pathological gambling and antisocial personality disorder were 6.2%, 8.3%, 4.9% and 7.4%, respectively. As shown in Table 4, there was no significant difference in the rates of MAP-induced psychotic disorder, mood disorder or alcohol use disorder between men and women. The women more frequently reported suicidal behavior, while pathological gambling and antisocial personality disorder were more common among the men before correction for multicomparison. However, after Bonferroni correction, pathological gambling and antisocial personality disorder were no longer significantly different between male and female subjects.
Table 4. Comparison of psychiatric comorbidity and gender in methamphetamine abuse
| ||Male (%) n = 180||Female (%) n = 145||Significance test|
|Methamphetamine psychosis||42 (23.3)||30 (20.7)|| 0.3 (1)|| 0.589|
|Any mood disorders||16 (8.9)||16 (11.0)|| 0.4 (1)|| 0.519|
|Major depression||12 (6.7)|| 8 (5.5)|| 0.2 (1)|| 0.668|
|Bipolar disorder|| 1 (0.6)|| 0||–|| 0.554|
|Dysthymic disorder|| 2 (1.1)|| 4 (2.8)||–|| 0.413|
|Depressive disorder, NOS|| 1 (0.6)|| 4 (2.8)||–|| 0.176|
|Suicidal behavior||10 (5.6)||52 (35.9)||47.8 (1)||<0.001*|
|Any alcohol use disorder||43 (23.8)||25 (17.2)|| 2.1 (1)|| 0.170|
|Alcohol abuse||26 (14.4)||15 (10.3)|| 1.2 (1)|| 0.315|
|Alcohol dependence||17 (9.4)||10 (6.9)|| 0.7 (1)|| 0.408|
|Pathological gambling||13 (7.2)|| 3 (2.1)|| 4.6 (1)|| 0.033|
|Conduct disorder||14 (7.8)|| 6 (4.1)|| 1.8 (1)|| 0.246|
|Antisocial personality disorder||20 (11.1)|| 4 (2.8)|| 8.2 (1)|| 0.005|
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The present study has found that there is high psychiatric morbidity and low access to mental health services associated with MAP abuse in Taiwan and, among individuals who have been incarcerated for MAP abuse in Taiwan, the women more commonly reported suicidal behaviors than the men. Compared with their male counterparts, more female subjects reported experience of mental disturbance and experience of psychiatric treatment.
The prevalence of major depression, alcohol use disorder, pathological gambling, and antisocial personality disorder in the present study was 6.2%, 20.9%, 4.9% and 7.4%, which is higher than those previously reported in community surveys of general population in Taipei (1.3%, 5.3%, 1.0% and 0.5%, respectively,19). The association of MAP abuse and those aforementioned psychiatric disorders is in large part consistent with the findings of psychiatric comorbidity in use disorders of other psychoactive drugs.4,9 It is worth noting that 22.1% of MAP-use subjects in the present study met criteria for past MAP-induced psychotic disorder. From an epidemiological point of view,20 there are a number of possible explanations for the observed association between MAP abuse and these comorbid associations. First, the observed relationship may be spurious. Second, MAP abuse and these comorbid psychiatric illnesses may share common etiological factors. Third, MAP abuse may cause some psychiatric disorders, or reveal a previously latent psychiatric illness. Positron emission tomography studies have suggested that dopamine transporter density in the caudate/putamen is reduced in persons using MAP.21–23 Sekine et al. found that the reduction of dopamine transporter may be longlasting, even if MAP use ceases, and that persistent psychiatric symptoms in persons using MAP, including psychotic symptoms, may be attributable to the reduction of dopamine transporter density.23 Fourth, certain psychiatric disorders may lead to MAP use disorder; this could occur through self-medication.24 It is suggested that efforts to prevent the occurrence of drug problems should focus on persons who have experienced a psychiatric disorder.25
In critically reviewing the area of gender differences in comorbidity with substance-use disorders, physicians should keep in mind the gender differences in psychiatric disorders in the general population.26 Epidemiologic surveys indicate that, in the general population, anxiety and affective disorders are more common in women, where antisocial personality disorder is more common in men.3,10,25 The reported difference in rates of disorders by gender among our subjects are, in large part, consistent with the results of the general population survey in Taiwan.19 Nevertheless, the fact that as many as 35.9% of the female MAP abuse subjects in the present study reported suicidal behavior warrants special attention to suicidal risk in the treatment of female individuals who abuse MAP.
A number of social factors differentiating women from men with regard to substance use have been identified in the present study. In the literature, compared to their male counterparts, more female substance-use subjects are separated or divorced,27 but female subjects have less frequent criminal problems.28 Griffin et al. reported that men are more likely to be employed, to hold higher status jobs, and to be self-supporting.14 The gender differences in the marital, legal and employment status of the present subjects were consistent with these previous reports. Our findings also revealed that crime other than illicit drug use was common among these MAP abuse subjects. Brady et al. reported a trend toward later onset of substance dependence in women.11 On the contrary, we found that among MAP abuse subjects in Taiwan, women were significantly younger and had a significantly earlier onset of MAP use than men. This finding was consistent with the gender differences among heroin addicts in Taiwan.29 One of possible reasons is that due to the mandatory military service policy in Taiwan, almost all of the men had served in the military, thus, compared with the men, the women might have been exposed to drug use earlier.
Psychosis after MAP use was not uncommon among our subjects. In most subjects, psychotic symptoms did not persist long after stopping MAP. The psychotic symptoms subsided within 1 month of cessation of use in most cases (95.9%). The rate of prolonged MAP psychosis was reported to be much higher among MAP-use subjects from the psychiatric hospital using the same assessment instruments as those in the present study.15 This demonstrates that prolonged MAP psychosis does exist, but a study of only hospital-based MAP-use subjects will be likely to over-emphasize chronicity of MAP psychosis. In the present study, those who had a history of psychosis prior to MAP use and those for whom psychosis was closely related to other psychedelic drugs were not included for analysis. Whether the three subjects who had psychosis for more than 1 month after stopping MAP should be diagnosed as having schizophrenia or MAP psychosis is questionable. The DSM-IV suggests that psychotic symptoms after use of psychedelic drugs are better accounted for by a primary psychotic disorder if these symptoms persisted for more than 1 month after the end of substance intoxication. However, MAP has been reported in several studies to result in psychotic symptoms lasting several months or more.30–32
In Taiwan, persons are sentenced to the detention center for simply using MAP. It is reasonable to propose that the characteristics of the subjects from the detention center were similar to those of persons using MAP in the community. Although more than one-third of the subjects from the detention center reported having experienced mental disturbance, only 8.9% had visited psychiatric professionals. Not surprisingly, in substance abuse (characterized by denial of illness), these subjects were poor consumers of treatment services. Myers et al. also reported in the Epidemiologic Catchment Area study that only one in seven substance abuse subjects (13.6%) were likely to have attended mental health clinics during the previous 6 months, and that this situation was worse for persons who abused illicit drugs.33 Among the MAP abuse subejct, we found that the women more commonly reported mental disturbance, occupational impairment, and seeking treatment. These findings are consistent with a previous study of cocaine abuse subjects in which is was reported that women experienced more residual problems (e.g. depression and job dissatisfaction) than men after becoming drug free.14
The present investigation was a retrospective study. Reporting and observer bias could not be excluded but these were minimized by applying highly structured instruments and employing trained researchers, and being supported by the interrater reliabilities for diagnosing MAP psychosis and other psychiatric disorders. The interrater reliabilities for mood disorders, alcohol use disorders and pathological gambling were not as good for MAP psychosis. It was not uncommon that use of MAP was intermingled with mood changes, alcohol drinking and gambling. Therefore it was sometimes difficult to determine whether these were primary psychiatric disorders or behaviors influenced by MAP use. The instruments used in the present study did not address all psychiatric illnesses, and so some mental disorders such as anxiety disorders and personality disorders other than antisocial personality disorder were not identified. Therefore, the gender differences of these unstudied disorders remain unknown. To sum up, among the persons who abuse MAP in Taiwan there exist certain differences in the rates of psychiatric illnesses and in the treatment-seeking behaviors between the males and female subjects. The gender differences in the prevalence of these disorders were, in large part, consistent with those reported in the general population. Nevertheless, drug treatment centers should be aware of these differences based on gender.