Mental health articles

Despite the general health advantage of city dwellers, incidence(the rate at which new disease events occur in a population) and prevalence (the number of events, e.g., a given disease, in a given population at a designated time) of specific mental disorders seemto be increased in this population. Meta-analytic studies report thatamong individuals living in cities, the prevalence of all psychiatric disorders is increased by 38%, of mood disorders by 39%, and of anxiety disorders by 21%, as compared to inhabitants of rural areas. Adjustment for potential confounders like age,gender, marital status, social class or ethnicity had limited impacton these findings, indicating that these population characteristics do not substantially contribute to the observed disparities.

The most striking urban-rural difference in mental disorder riskis the increased incidence of schizophrenia in people born andraised in urban areas. Schizophrenia is a seriousmental disorder affecting approximately 0.5e1% of the worldpopulation, leading to major suffering and disability in many patients. The first report on the increased incidence of schizophrenia in urban areas dates back to 1939, when increased incidence rates for this disorder were observed in densely populated inner city areas of Chicago, as compared to the city’s periphery. The increased schizophrenia incidence in urban areas has been corroborated by subsequentstudies,including demonstration of a doseeresponse relationship. A systematic review of the literaturereported an increase in schizophrenia risk among citydwellers of 1.92 in males and 1.34 in females.Interestingly, the effect of exposure to the urban environment seems to be strongest during the time period from birth to age 15, as compared to exposure later inlife.

Many researchers believe that urbanicity stands as a proxy forenvironmental factors that await identification. Possibilities discussed in the literature includesocioeconomic adversities, environmental pollution, exposure totoxins and infectious agents, drug abuse, and others. However, the difference in schizophrenia incidence persisted when analyses were adjusted for many of these variables, indicating that these factors probably exert no major effect on the association. The socialdrift hypothesis also addressed this issue and proposed that individuals with pre-existing mental disorders tend to move to asocioeconomic lower status and to cluster in urban areas, thus raising the false impression that city living predisposes to increased psychosis risk. However, several observations argue against thishypothesis. First, there is both a doseeresponse relationship betweenduration of exposure to urbanicity and morbidity risk and anearly linear association between city size and psychosis incidence,indicating that the urban-rural difference constitutes the etiologicfactor. Second, in subjects withhigh psychosis risk, moving to a rural area attenuates schizophreniaincidence. This reversibility alsoargues in favour of urbanicity itself, not social drift, as the causativeagent. Third, in migrants, the effect of city living on schizophreniaincidence is greatest among second-generation individuals. This observation is not easilyexplained by social drift as the primary event. In conclusion, thefactors mentioned above seem an unlikely explanation for theobserved urban-rural difference in mental disorders incidence.Currently, many researchers favour the hypothesis that the urbanenvironment stands as a proxy for increased exposure to socialstress.

Tags: disorder, mental, mental disorder, risk