PREVALENCE OF PSYCHIATRIC DYSFUNCTION IN THE URBAN-POPULATION OF MEXICO

The present report is based on information gathered in 1988 on a repre sentatives subsample of adults aged 18 to 64 years, living in urban ar eas, during the first National Survey on Drug Abuse. The sample frame was a household survey based on the master frame for epidemiological s tudies in the country. The design was polietapic and stratified and th e individual subject at the household was the last sampling unit. This study is the first in Mexico that has intended to estimate the preval ence of specific psychiatric disorders in the general population throu ghout the country. In 1988, when this study was planned, most epidemio logical studies used the PSE-CATEGO on which the authors had previous experience. The DIS had also been used on the ECA study in the United States, and we had experience in it. Nevertheless, both instruments re quired experienced personnel and both were very long for the purposes of the main study. Using our previous experience, we decided to elabor ate a questionnaire that could be easily and reliably administered by lay interviewers throughout the country, and simple enough to be under stood by the person interviewed, and also resembling the structure of the PSE in order to further organize the clinical information into the syndromes and apply the ID-CATEGO rules. Items were selected from scr eening instruments such as the SRQ, the CES-D expanding the evaluation to the previous month, a scale that evaluates hopelessness and suicid al thoughts, and some questions which were adapted form the DIS follow ing the DSM-III criteria and that were also included in the PSE. All q uestions were responded with three options: yes, no and don't know, sp ecifying the presence of the symptom either in the previous month or d uring lifetime, as wells its severity. Finally, the questionnaire incl uded 60 items with which most of the non psychotic syndromes from the PSE were integrated and combined in order to arrive to a diagnostic cl ass following the ID-CATEGO rules. Also three psychotic syndromes were created and combined to arrive to a tentative diagnosis of schizophre nia or to an unspecific psychosis. A complete description of the syndr omes, rules for combinations and the questionnaire can be obtained fro m the first author. The average weight value was used throughout the a nalysis it was obtained by the average of all the weighting values for each subject using it as the divisor of each unit; by this means the sampling probability of the subjects was preserved as well as the samp le size. The average weighted sample of subjects aged 18 to 64 years o ld included 888 males and 1096 females. Results are presented by group s of age and gender. Diagnostic definitive classes suggesting a bipola r disorder showed a prevalence of 1.1 % for males and 0.3 % for female s, Classes indicating a major depressive disorder were significantly m ore frequent in women, 3.9 % than in men 2.2 % and specially among the 45-64 age group. Probable schizophrenic disorders were equally found showing a 0.7 % prevalence. The four diagnostic classes indicative of a probable psychotic disorder showed and overall prevalence of 5.4 % i n males and 5.8 % in females. Minor psychiatric disorders were, as exp ected, more frequent. Simple depression was more common in men of the younger and elder groups. Neurotic depression prevailed in women showi ng the same tendency on age. Also, obsessive-compulsive disorder was m ore frequent in women. The overall prevalence of psychiatric disorders was estimated in 16.7 %; additionally, epilepsy showed 3.7 % lifetime prevalence equally affecting both sexes. Unspecific syndromes were re ported in 30 % and asymptomatic population represented 35 %. The resul ts obtained in this study are compared and discussed with the findings reported recently in the bibliography.