ABSTRACT
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Abstract: Mental health frames and policies to enforce them cannot be excluded from the social context, neither the population's health conditions or the international tendencies. Their strategic place depends on the role they play in the global milieu, and on the benefits derived from what is done in terms of prevention and attention within the field. Psychiatric epidemiology serves as a tool for knowing mental disorders distribution, the risk factors implied in their etiology and evolution, as well as the elements influencing their detection and treatment. But psychiatric epidemiology has remained behind other branches of epidemiology given the problems for conceptualizing and measuring mental disorders. Thus, most of the work has been basically descriptive. Nevertheless it has been possible to move forward through historical series, analyses of community diagnosis, health services evaluation, risk measurement, description of clinical frames, identification of new syndromes and its related causes, and in carrying out national and international representative surveys in general population. This paper has four objectives: 1. to present an overview of the work done in epidemiologic psychiatry in Mexico for the last 30 years; 2. to analyze the main areas explored; 3. to identify the most used designs; and 4. to enumerate the populations studied. Method. Articles about different aspects related to study and analysis of psychiatric epidemiology in Mexico were collected, including those reporting empirical results. The search was performed in a bibliographic database consulted in the Centro de Información en Salud Mental y Adicciones (CISMAD), located at the Instituto Nacional de Psiquiatría Ramón de la Fuente. Approximately 158 papers published in national and international journals were reviewed. Results. In the 1970's, work was aimed towards historical analysis seeking to provide an epidemiologic view of psychiatric disorders in Mexico. Interest was set on aspects related to attention of mental patients, the teaching of psychiatry, and in the advance of psychiatric knowledge. Some studies were done to have a look at the frequency and characteristics ofcertain diseases in unexplored populations. During the 1980's there was a renewed interest in dissecting the status of epidemiologic psychiatry and mental health, together with an intention to state its role in the future. Cross sectional studies were performed to know the prevalence ofdifferent mental illnesses in medical care. Validity and reliability of several detection and diagnosis instruments were evaluated, and some essays about the importance of having a clear view of attention needs and demands were carried out. At the beginning of the 1990's there were descriptive studies in rural and urban populations to describe the main elements determining the use of health services and the quest patterns for different attention options. New diagnosis instruments were used in subjects attending the first and second levels of care. Research on schizophrenia began with reviews and dissertations about its status in Mexico and other countries. Results of the Mental Health National Survey showing prevalence in general population were made public. Home base surveys made possible to know the scope of mental illness in children, adolescents, and adults. The use of epidemiology in child psychiatry allowed the inclusion of developmental psychopathology in the analysis of the interaction and interdependence of biological, psychological, and social variables. The 21st century set the emergence of the first longitudinal reports on suicide. Work continues on the prevalence of mental illness and new approaches on risk factors are added. Research on the frequency of disorders from well-defined diagnosis criteria is signed. Use and abuse of substances, and violence against women are studied to know their effects on mental health. The Survey on Psychiatric Morbidity was planned and conducted with great methodological rigor, and thus it was included in the first generation of ICPE studies, which has enabled data comparison on an international basis. Results have shown that depressive disorders are the most recurrent, whereas disorders related to substance abuse and dependence affect basically men, and that anxiety disorders are the most chronic. In 2000, the World Health Organization launched an initiative to make national epidemiologic studies in different countries, and Mexico was the first Latin American country to participate. The National Psychiatric Epidemiology Survey initial results have confirmed that the prevalence of disorders along life is 28.6%, and that annual prevalence is 14%. Discussion. It is important to underline the need to pay attention to mental health problems from a preventive approach. In this respect, Mexico is a little behind and it is urgent to grow according to the advances, instruments, and techniques used in other countries. It is also important to acknowledge the work done so far; in this sense, the development of national surveys accounts for it. General population studies allow for the generation of an overview of the needs and the basic issues to create preventive interventions. Mexican epidemiologic psychiatry is in a developmental stage, stressed by the use of standardized diagnosis criteria to get comparable data (both from Mexico and other countries in the world). However, the study designs employed until now do not allow for the exploration of the temporary evolution of disorders and related factors to be more exhaustive. Besides, there are limitations in evaluating health services, which could be overcome through cost-effectiveness analyses. In the national context it is notorious the lack of inquiring about the diagnosis boundaries, which should be one of the main directions of psychiatric epidemiology in the next years. This would be highly relevant taking into account that Mexico is a transition country that accepts and uses both European and American criteria. It should be mentioned also that, although Mexico has the same kind of problems than other countries, research has shown they are smaller, which makes studies on protective and risk factors a priority for the future. There are still certain aspects of epidemiology which remain practically untouched in research. For instance, it is important to focus on rural areas, on migrant populations, and on native groups to overcome the existing backwardness. Another important topic in the prevention area is the work to do carried out with mental problems during childhood and adolescence. Longitudinal studies would mark the path to evaluate different types of factors: genetic, biologic, familiar, psychodyna-mic, social, and economic. It is also important to analyze the interaction among them to know its impact on etiology and on the development of psychopathology during life.
ABSTRACT
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Abstract: A genetic epidemiology paradigm employed in the identification of genes associated with a disease depends on the comparison of the frequency of common genetic variants between groups of individuals who possess a relevant trait versus those who do not show the trait (i.e., cases vs. controls genetic association study). The adequate classification of groups of contrast is therefore of seminal importance for the identification of relevant genes. For psychiatric disorders, the careful clinical evaluation of particular symptoms is the basis for the classification of the "affected or disease group". However, in many psychiatric genetics studies the constitution of the "control" or "normal" group has been based only on the absence of an overt expression of symptoms, where no particular emphasis is given to the symptom evaluation to exclude the phenotype. The use of psychometric instruments can help to assess some behavioral traits of clinical relevance. In turn, these assessments could help in the diagnosis, prognosis and treatment of disorders. Moreover, quantitative assessments let determine if these traits belong to the normal range of variation in a population or could be a deviation of the trend. The Symptom Checklist 90 (SCL90) is a 90-item self-report inventory that assesses the level of distress recently experienced by the subject. It is comprised of nine dimensions: somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, psychoticism and a General Severity Index (GSI). Although the SCL 90 is a well-accepted and widely used instrument in research and clinical practice in many countries, we found a scarcity of relevant studies for Latin America and a lack of normative data for Mexican populations. The aim of the present report was to evaluate the reliability and construct validity of the SCL 90. Method Subjects A Spanish translation of the original SCL90 English version was administered to a group of 228 subjects, comprised by relatives of patients, members of a family parents association, medical and paramedical staff, and college students. The SCL90 was included within a battery of clinical and psychometric assessments of individuals participating at ongoing research protocols on the genetics of personality and creativity. An additional group of 30 ambulatory psychiatric patients from the Instituto Nacional de Psiquiatría Ramón de la Fuente (INPRF) was also analyzed. The instrument was applied by experienced qualified personal. Statistical analyses Statistical analyses were performed using SYSTAT 8.0. Reliability was evaluated by assessing the response consistency obtained from those items with similar questions. The Cronbach's alpha coefficient was used as the measure of the internal consistency for all nine subscales for this purpose. Construct validity was assessed using two complementary criteria: a) evaluating pre-conceptual hypotheses and b) analysing psychometric data. In the first case, and based on previous reports showing that the level of distress is a function of social-demographic, gender and clinical status, it was hypothesized that the mean scores should be higher in women, younger people and individuals affected with a psychiatric condition. ANOVA and F statistics were computed using the mean scores and standard deviations for the nine dimensions and GSI. In addition, the extent of correlation between individual items and its own subscale dimension should be higher than the other subscales, and the level of correlation between each item and the GSI should be positive. In this case, a Spearman rank correlation matrix was constructed for the SCL90 items and the nine subscales, as well as the GSI. Results Internal consistency All but two of the nine SCL90 dimensions showed good internal consistency values (Cronmbach's alphas >0.7-0.85); with only hostility and paranoid ideation subscales reaching an acceptable value (>0.6-<0.7). The overall Cronbach's alpha score obtained for the GSI was 0.96. Construct validity Fifty-six of the SCL90 items showed a Spearman rank correlation coefficient value (r > 0.5), 23 items showed a moderate value (r >0.25 and <0.5), and only one item showed a weak correlation with its own scale (r =0.2). Only in one case (item 80) the highest correlation value did not correspond with its particular dimension. Mean scores for all of the nine dimensions of the SCL90, as well as the GSI, were higher in women compared to men, and in subjects < 25 years old. The ANOVA showed statistically significant differences (p< 0.01) for somatization, depression, obsessive-compulsive, interpersonal sensitivity, anxiety, hostility dimensions as well as for the GSI. Likewise, an ANCOVA, using age as a covariable, showed an age effect for the last five dimensions (p < 0.005), and in lesser degree for paranoid ideation (p =0.014). Likewise, both men and women patients populations showed higher scores for each dimension compared to general population. Comparison between Mexican and Argentine populations Independent sample t test showed meaningful differences for three scales (obsessive compulsive, interpersonal sensitivity, anxiety, as well as for the GSI) in men and women. Somatization was statistically different only for women from Argentina. Percentiles calculated for each one of all dimensions and the GSI showed a general tendency to be higher for the Mexican population compared with data from Argentina. Discussion The SCL90 is a self-report inventory where the subject reflects his/her perception about the degree of distress that he/she is experiencing. It is used by clinicians and researchers to gather information about the mental health of subjects. In the mental health field, the SCL90 has been employed world-wide to monitor the quality of the medical-psychological interventions, as well as a screening tool to identify psychopathology symptoms. We examined certain psychometric properties of the Spanish version of the SCL90, as there is a lack of normative data for Mexico. The internal consistency reliability for the scale as a whole and for individuals subscales was in general terms adequate for the group of individuals examined. Validity was assured throughout the confirmation of expected differences of groups of comparison and by the good correlation agreement among specific items and their particular dimensions. Compared to the only Latin American study, the mean scores for Mexican population were higher than in Argentina and even higher compared with the USA normative sample. Among others putative factors, translation issues (e.g. use of double negative sentences) and /or cross-cultural differences (e.g. demographic characteristics, socioeconomic differences) should be taken into account to explain these differences; therefore caution should be applied when comparing data of different populations. Among the limitations of this study we must include the analysis of a non-population sample of modest size. Nonetheless, we can conclude that the SCL90 inventory shows good psychometric attributes that may be useful for research and/or clinical purposes. Percentiles rank data can be used as a starting reference for others researchers interested in evaluating in a fast and simple way the psychological distress status of a particular individual, underlying the necessity of developing on a short-term basis normative data for the Mexican population.