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Background: Prescription drug misuse (PDM) is a critical mental health issue relating to psychiatric morbidity. This study investigated the prevalence of PDM and its associated psychopathology and psychosocial factors in the general population in Taiwan. Methods: The survey randomly selected a representative sample >15 year-olds using the stratified proportional randomization method. The measurements included demographic variables, previous experience with PDM, self-rated physical and mental health, health self-efficacy, risk factors for suicidality, and psychological distress. Results: The weighted one-year prevalence of PDM was 8.5% (n = 180) among 2126 participants. Those with psychological distress and lifetime suicide ideation (23.3%) or suicide attempts (5.0%) were significantly associated with PDM. PDM was also prevalent among those with poorer self-rated health and lower self-efficacy. Insomnia (OR = 1.52), depression (OR = 1.77), and low self-efficacy (OR = 2.29) had higher odds of PDM after adjustment in the logistic regression model. Conclusions: Individuals who misused prescription drugs had a higher prevalence of psychological distress and suicidality and lower levels of self-rated health. Prescription drug misuse problems should be screened for early prevention when prescribing medications for people with insomnia, depression, or lower perceived health beliefs or conditions.

To the Editor: Ketamine, an NMDA (N-methyl-d-aspartate) glutamate antagonist, commonly used as an anesthetic agent, has emerged as a major substance of abuse particularly in Asia.1 Here, we present, to our knowledge, the first case of a patient who developed major depressive episodes after heavy and long-term ketamine use. Case report. Mr A, a 38-year-old man with no psychiatric family history, was admitted to the substance treatment ward for ketamine dependence. He started recreational use of ketamine at age 26 years and developed ketamine dependence (daily dosage: 6 g) such as tolerance and withdrawal symptoms (eg, craving, anxiety, and irritability) at age 30. Obvious impairment of social, occupational, and personal function was noted. The patient reported difficulty in stopping ketamine use in spite of his emergency department visits for physical complications such as abdominal cramping and urinary frequency. After being ketamine dependent for 2 years, he developed depressed mood, diminished interest, poor appetite, insomnia, feelings of hopelessness and helplessness, and suicidal ideation for 2–3 months. Mr A was diagnosed with major depressive disorder on the basis of DSM-IV-TR criteria. He refused medication help, and his depressive symptoms were only partially improved with psychological counseling. After 1 year, Mr A lost his source of ketamine supply, and a complete remission of his major depression was noted after stopping ketamine use for 3 weeks. After abstaining from ketamine for 5 years (age 38), he restarted ketamine use and rapidly became ketamine dependent with daily consumption up to 6 g. Another episode of major depression was observed shortly after his ketamine dependence relapsed. He increased his ketamine dose to 10 g for self-medication; however, the depressive symptoms worsened. He was therefore admitted to our ward for ketamine dependence treatment. At admission, laboratory tests revealed no abnormalities except for testing positive for ketamine. He showed prominent depressive symptoms with Beck Depression Inventory (BDI)2 scores up to 35. Oral benzodiazepines and sertraline 100 mg/d were prescribed for ketamine withdrawal syndrome and major depression. His depressive symptoms improved rapidly after 2 weeks of hospitalization, and he was discharged. Several interesting features of this case indicate the causal relationship between heavy ketamine use and major depression. First, the patient developed 2 episodes of major depression after heavy ketamine use. Second, he reported worsening of depressive symptoms after increasing ketamine dosage, indicating a possible dose relationship. Third, his depressive episodes rapidly resolved after being abstinent from ketamine, which could not be explained by treatment effects of antidepressants. Several possible mechanisms underlie ketamine-induced major depression. First, prolonged ketamine exposure is associated with direct neurotoxicity. An animal study3 suggested that repeated exposure to ketamine markedly reduced neural activities in areas like ventral tegmental area and substantia nigra, while dysfunctions of these neural circuits have been implicated in neuropsychiatric disorders including depression. Second, long-term and heavy alcohol consumption may lead to development of depressive disorders.4 Ketamine, similar to alcohol, works as an NMDA antagonist and may lead to the development of major depression. Third, chronic substance use disorder may itself lead to major depression, evidenced by neuroimaging studies showing similar alterations in frontal-limbic brain activity in chronic substance-abusing patients and depressive patients.5 High prevalence of major depression in ketamine-abusing individuals was shown in previous studies. A 3-year longitudinal study6 revealed that the depression scores were higher in ketamine-abusing patients than polysubstance-abusing patients. A follow-up study7 demonstrated greater BDI scores in frequent ketamine users than in controls. In a recent clinical study8 of treatment-seeking ketamine users, the prevalence of major depression was up to 27.9%. Here, we present the case of a patient whose major depressive episodes developed after heavy ketamine use and rapidly resolved after abstaining from ketamine. This unique case highlights the need for investigating the long-term effects of ketamine use.

Methamphetamine (METH) abuse is an increasing public health problem worldwide. Many of the METH-induced physical and mental problems are associated with the neurotoxic effects of METH. Animal studies have shown that brain-derived neurotrophic factor (BDNF) decreased after repeated amphetamine administration and increased at 30 and 90 days from psychostimulant withdrawal, suggesting that there might be a psychostimulant-induced neuroprotective dysfunction followed by a neuroadaptive process in the brain. However, current research on the role of BDNF in human METH addiction is limited, particularly during early withdrawal. The aim of this study was to assess the serum BDNF levels in METH abusers during the early withdrawal stage. Two groups of subjects were enrolled: (1) 59 DSM-IV METH abusers confirmed by board-certified psychiatrists during the first 3 weeks of withdrawal; (2) 59 age- and sex-matched healthy controls. We found that serum BDNF levels were significantly and constantly lower in the METH abusers during early withdrawal than those of the healthy controls. This indicates that METH abusers might have severe BDNF dysfunction and an impaired neuroprotective function after repetitive METH misuse.

The empirical results show that the dynamic conditional correlation (DCC) and the bivariate asymmetric-IGARCH (1, 2) model is appropriate in evaluating the relationship of the Japan’s and the Canada’s stock markets. The empirical result also indicates that the Japan and the Canada’s stock markets is a positive relation. The average estimation value of correlation coefficient equals to 0.2514, which implies that the two stock markets is synchronized influence. Besides, the empirical result also shows that the Japan’s and the Canada’s stock markets have an asymmetrical effect, and the variation risks of the Japan’s and the Canada’s stock market returns also receives the influence of the good and bad news, respectively.

The aim of this study is to examine the relationship between alcohol dependence and oxidative status. The biochemical parameters and antioxidants status were measured among 28 patients with alcohol dependence. Nineteen healthy persons without drinking problem were recruited as the control subjects. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyltransferase (gamma-GT), and levels of cholesterol, triglyceride (TG), and uric acid were significantly increased in the specimen of patients compared with control. Serum malondialdehyde (MDA) levels of the patients were found to be significantly increased compared with controls and decreased after abstinence. Superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities were, respectively, 86% and 37% lower in alcoholic patients. After 14 d of abstinence, SOD activity was significantly reduced by 85%, CAT by 52%, and GPX by 54%, whereas no change was found in activity of glutathione reductase (GR). The duration of alcohol dependence is significantly correlated with the levels of MDA. In addition, the activity of CAT was significantly correlated with MDA levels. The results of this study suggest that oxidative stress occurred during alcohol dependence and subsequently affected the antioxidants mechanisms.

Methamphetamine (METH) abuse is an increasing public health problem worldwide. Many of the METH-induced physical and mental problems are associated with the neurotoxic effects of METH. Animal studies have shown that brain-derived neurotrophic factor (BDNF) decreased after repeated amphetamine administration and increased at 30 and 90 days from psychostimulant withdrawal, suggesting that there might be a psychostimulant-induced neuroprotective dysfunction followed by a neuroadaptive process in the brain. However, current research on the role of BDNF in human METH addiction is limited, particularly during early withdrawal. The aim of this study was to assess the serum BDNF levels in METH abusers during the early withdrawal stage. Two groups of subjects were enrolled: (1) 59 DSM-IV METH abusers confirmed by board-certified psychiatrists during the first 3 weeks of withdrawal; (2) 59 age- and sex-matched healthy controls. We found that serum BDNF levels were significantly and constantly lower in the METH abusers during early withdrawal than those of the healthy controls. This indicates that METH abusers might have severe BDNF dysfunction and an impaired neuroprotective function after repetitive METH misuse.

This paper uses the Malaysia and the Singapore’s stock prices of material from January 3, 2000 to July 20, 2007, discussing the model construction and their associations of between Malaysia and Singapore’s stock markets, and also uses Student's t distribution to analyze the proposed model. The empirical results show that the mutual affects of the Malaysia and the Singapore’s stock markets may construct in bivariate IGARCH (1, 1) model with a DCC. The empirical result also shows that between Malaysia and Singapore’s stock market returns exists the positive relation- namely these two stock market return’s volatility is synchronized influence, the average estimation value of the DCC coefficient of two stock market returns amounts to 0.3826. Also, Malaysia and Singapore's stock markets do not have the asymmetrical effect in the research data period. Based on the DCC (Engle, 2002), the DCC and the bivariate GARCH model have a better explanatory ability compared to the bivariate GARCH model with a constant conditional correlation.

This paper studies the relatedness and the model construction of exchange rate volatility and the South Korea stock market returns. Empirical results show that we can construct a bivariate EGARCH(1, 2) model with a dynamic conditional correlation (DCC) to analyze the relationship of exchange rate volatility and Korea stock market returns. The average estimation value of the DCC coefficient for these two markets equals to -0.1961, this result indicates that the exchange rate volatility negatively affects the South Korea stock market. Empirical result also shows that there exists an asymmetrical effect on the South Korea stock market, but the exchange rate volatility does not have the asymmetrical effect. Based on the good news and bad news (Nelson, 1991) of the stock market, the bivariate EGARCH(1, 2) model with a DCC has the better explanation ability compared to the bivariate GARCH(1, 1) model.