Molecular epidemiology of major depressive disorder

Major depressive disorder causes significant morbidity, affecting people's ability to work, function in relationships, and engage in social activities. Moreover, major depressive disorder increases the risk of suicidal ideation, attempted suicide and death by completed suicide. There is evidence that chronic stress can cause major depressive disorder. As for genetic factors, only minor susceptibility genes have been reliably identified. The serotonin system provides a logical source of susceptibility genes for depression, because this system is the target of selective serotonin reuptake-inhibitor drugs that are effective in treating depression. The 5-hydroxytryptamine (serotonin) transporter (5-HTT) has received particular attention because it is involved in the reuptake of serotonin at brain synapses. One common polymorphic variant of the 5-HTT-linked polymorphic region (5-HTTLPR), which affects the promoter of the 5-HTT gene, causes reduced uptake of the neurotransmitter serotonin into the presynaptic cells in the brain. The authors discussed the relationship between genetic polymorphisms and major depressive disorder, with special emphasis on the 5-HTTTLPR polymorphism. As the 5-HTTLPR polymorphism was significantly associated with an increased risk of major depressive disorder, the 5-HTT gene may be a candidate for a major depressive disorder susceptibility gene. As major depressive disorder is a multifactorial disease, an improved understanding of the interplay of environmental and genetic polymorphisms at multiple loci may help identify individuals who are at increased risk for major depressive disorder. Hopefully, in the future we will be able to screen for major depressive disorder susceptibility by using specific biomarkers.

A proposed approach to suicide prevention in Japan: the use of self-perceived symptoms as indicators of depression and suicidal ideation

The incidence of suicide in Japan has increased markedly in recent years, making suicide a major social problem. Between 1997 and 2006, the annual number of suicides increased from 24,000 to 32,000; the most dramatic increase occurred in middle-aged men, the group showing the greatest increase in depression. Recent studies have shown that prevention campaigns are effective in reducing the total number of suicides in various areas of Japan, such as Akita Prefecture. Such interventions have been targeted at relatively urban populations, and national data from public health and clinical studies are still needed. The Japanese government has established the goal of reducing the annual number of suicides to 22,000 by 2010; toward this end, several programs have been proposed, including the Mental Barrier-Free Declaration, and the Guidelines for the Management of Depression by Health Care Professionals and Public Servants. However, the number of suicides has not declined over the past 10 years. Achieving the national goal during the remaining years will require extensive and consistent campaigns dealing with the issues and problems underlying suicide, as well as simple screening methods for detecting depression. These campaigns must reach those individuals whose high-risk status goes unrecognized. In this review paper, we propose a strategy for the early detection of suicide risk by screening for depression according to self-perceived symptoms. This approach was based on the symposium Approach to the Prevention of Suicide in Clinical and Occupational Medicine held at the 78th Conference of the Japanese Society of Hygiene, 2008.

Suicidal risk factors and completed suicide: meta-analyses based on psychological autopsy studies

The purpose of the present review is to evaluate the effects of common risk factors for suicide by meta-analyses using data extracted from studies based on the psychological autopsy method. We focused on five common risk factors of suicide: substance-related disorders, mood disorders, adverse marital status, adverse employment status, and self-harm behaviors. A total of 24 articles were identified from MEDLINE in which the crude odds ratio (OR) could be calculated for the above five risk factors through 30 April 2007, using such search keywords as "suicide," "psychological autopsy," and "case-control study." Overall, both substance-related disorders [OR = 5.24; 95% confidence interval (CI) = 3.30-8.31] and mood disorders [OR = 13.42; 95% CI = 8.05-22.37] were strongly associated with suicidal risk. Suicidal attempt and deliberate self-harm, which can directly lead to completed suicide, have been shown to be very strongly associated with suicidal risk [OR = 16.33; 95% CI = 7.51-35.52]. Effects of social factors such as adverse marital and employment status were relatively small. As substance-related disorders and mood disorders were strongly associated with an increased risk of completed suicide, the comorbidity of these two disorders should be paid a maximum attention. The effective prevention of suicide depends on whether we can successfully incorporate these personal factors as well as social factors into an adequate multi-factorial model.

Quantitative Analysis of the Thermal Image of the Hand Dorsum in the Assessment of Peripheral Circulatory Impariment in Workers Exposed to Hand-Arm Vibration / 日本温泉気候物理医学会雑誌

Infrared thermography was performed on 38 forestry workers. The thermograms were analyzed separately for the left and right hands of each subject. Of 75 hands evaluated, vibration-induced white finger was noted in 18 (VWF group), and no symptoms were noted in 57 (non-VWF group). In addition to the above two groups, 42 subjects (84 hands) who had no symptoms of vibration exposure were used as a control group. Based of the thermograms taken after a local warming of the hands for 5min, the temperature distributions of the dorsal aspect of subject's hands were evaluated, and the thermal images of the hand with VWF were categorized into three main patterns. To establish a quantitative evaluation index that incorporates the characteristic thermal image observed in the VWF group, we constructed the representative parameters for each of the three thermogram patterns, and a linear discriminant analysis was performed using the presence or absence of VWF symptoms as the dependent variable and the constructed parameters as the independent variables. A discriminant score derived from this model expression was used as the evaluation index. The accuracy of the index was estimated according to a receiver operating characteristic (ROC) curve, and the area under the curve of 0.942 was obtained (p<0.001). When the cutoff point was set at the maximum point in the Youden index, the sensitivity of the VWF group was 94.4%, and the specificity of the non-VWF group and control group was 84.2% and 89.3%, respectively. These findings suggest that this newly proposed quantitative analysis method, which uses the thermal distributions of the dorsal side of the hand as indicators, may be useful for evaluating peripheral circulatory impairment of HAVS.