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.His conclusion that phobias are common, disabling anddifficult to treat, and constitute a major public health problem issubstantiated by the epidemiological evidence, but the expectation thatthe currently ongoing World Mental Health Survey will result in a betterunderstanding of many things about phobias, if only because a commoninstrument will have been used in all countries is unwarranted.CIDI-based survey epidemiology is certainly contributing to the populationmapping of prevalences and disability rates, but its capacity to unravel thecomplex issues of etiology is limited.Epidemiology is not restricted to its descriptive branch (sometimesreferred to as head counting ).The tools of analytical, risk-factor andgenetic epidemiology have a better chance of allowing us to understandcausation and, ultimately, prevention.To illustrate this point, I choose fourexamples of incisive and challenging research demonstrating that theetiology of phobias is complex and likely multifactorial, but not intractable.An example of epidemiological dissection of anxiety and depressivedisorders is provided by a prospective study by Brown and colleagues [3,4]of a sample of 404 British women considered to be at high risk fordepression (being inner-city residents, working class, many of them singlemothers, with a child living at home).Following in-depth initial interviews,the women were re-interviewed for psychiatric symptoms at one-year, two-year and (a quarter of the sample) at eight-year follow-up.Indices ofchildhood adversity (physical or sexual abuse, parental indifference) andadult life adversity (death of a child, death of a partner, multiple abortions,1Centre for Clinical Research in Neuropsychiatry, University of Western Australia, Perth, Australia 82 ____________________________________________________________________________________________ PHOBIASsexual abuse, domestic violence) were constructed and used in log-linearanalyses modelling the relationship between such risk factors andpsychiatric disorder.The one-year prevalence of DSM-III-R anxietydisorders (panic disorder, agoraphobia, social phobia, simple phobias,generalized anxiety) was 23.8%.Close to half of the sample had experiencedclinically significant depression at some point during the anxiety episode,while only 7.2% had depression without anxiety.Panic disorder was mostlikely (67%), and simple phobias least likely (11%), to be associated withdepression.The time spent in anxiety (8.1% of the one-year periodpreceding the interview) was double the time spent in depression, andanxiety disorders were more often chronic than depression.Onsets ofanxiety disorders within an ongoing depressive episode were rare;however, onsets of depression among those with ongoing anxiety disorderwere common.The analysis of risk factors highlighted different mechanisms ofoperation for psychosocial factors in depression and anxiety.While adultlife adversity and low levels of social support were related to depression,vulnerability to anxiety was less influenced by current adversity or levelsof support and more by early adversity, constitutional factors, or both.About half of the women with anxiety disorder (particularly panicdisorder and agoraphobia) had experienced early adversity, whichremained significantly associated with anxiety after controlling for adultadversity.The study design allowed teasing out the separate contributions ofanxiety and depression to the commonly observed comorbidity of the twoconditions.The main contribution to comorbidity (44% of the total rate)resulted from the joint high prevalences of the two conditions, i.e.represented chance comorbidity.However, over 50% of the observedcomorbidity was non-chance, suggesting that factors other than childhoodand adult life adversity may play an important role.Although involvementof further psychosocial stressors could not be ruled out, the study suggestsan underlying common genetic liability, or a single neurodevelopmentalprocess, at the root of the comorbidity problem.My second example highlights the potential benefits from epidemio-logical studies of rare isolate populations that are relatively homogeneous,in both genetic and lifestyle respects.The Hutterites, a Protestant anabaptist sect founded in the 16th centuryby Jacob Hutter in Switzerland, are a genetic isolate with a high index ofconsanguinity resulting from a closed-in lifestyle, imposed by religiouspersecution and group migration that led them first to Russia and later onto the US and Canada, where they settled as small farming communities.The majority of the Hutterites (present number estimated at about 40 000)are the descendants of 89 individuals who formed a family at the end of EPIDEMIOLOGY OF PHOBIAS: COMMENTARIES _______________________________________ 83the 18th century.They represent an almost ideal founder population thathad experienced a relatively recent bottleneck, ensuring a high degree ofgenetic homogeneity.The medical and psychiatric profile of the Hutteriteswas first described in the 1950s by Eaton and Weil in a classic monographentitled Culture and Mental Disorders [5].The main finding of the study wasthe extremely low incidence of schizophrenia, which was hypotheticallyexplained as the result of sociogenetic selection: individuals with schizoidtraits or other schizophrenia-prone attributes were unlikely to adjust to thehighly collectivist ethos of the community and, hence, had low chances ofprocreation within the sect.A follow-up epidemiological study some 40years later [6] replicated the original finding of a low incidence of psychosesin the Hutterite communities, but it also revealed something that hadescaped the initial survey: an unusually high prevalence of neuroticdisorders, including anxiety and phobias.The prevalence rate of neuroticdisorders, at 86.7 per 1000, was more than twice the expected rate, based onthe general population of the area.Both cultural and genetic factors may be at work to produce thisphenomenon.While providing an extraordinary level of familial andcommunity support, the strict religious indoctrination, lifestyle regimenta-tion and conformity to tradition within the closely knit community may beconducive to excessive anxiety in many individual members with orwithout a specific genetic vulnerability.Such an interpretation would be inagreement with the findings of another population survey that in theOuter Hebrides [7] which revealed that the rates of chronic anxiety werehighest among the most socially integrated members of the community (e.g [ Pobierz całość w formacie PDF ]
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.His conclusion that phobias are common, disabling anddifficult to treat, and constitute a major public health problem issubstantiated by the epidemiological evidence, but the expectation thatthe currently ongoing World Mental Health Survey will result in a betterunderstanding of many things about phobias, if only because a commoninstrument will have been used in all countries is unwarranted.CIDI-based survey epidemiology is certainly contributing to the populationmapping of prevalences and disability rates, but its capacity to unravel thecomplex issues of etiology is limited.Epidemiology is not restricted to its descriptive branch (sometimesreferred to as head counting ).The tools of analytical, risk-factor andgenetic epidemiology have a better chance of allowing us to understandcausation and, ultimately, prevention.To illustrate this point, I choose fourexamples of incisive and challenging research demonstrating that theetiology of phobias is complex and likely multifactorial, but not intractable.An example of epidemiological dissection of anxiety and depressivedisorders is provided by a prospective study by Brown and colleagues [3,4]of a sample of 404 British women considered to be at high risk fordepression (being inner-city residents, working class, many of them singlemothers, with a child living at home).Following in-depth initial interviews,the women were re-interviewed for psychiatric symptoms at one-year, two-year and (a quarter of the sample) at eight-year follow-up.Indices ofchildhood adversity (physical or sexual abuse, parental indifference) andadult life adversity (death of a child, death of a partner, multiple abortions,1Centre for Clinical Research in Neuropsychiatry, University of Western Australia, Perth, Australia 82 ____________________________________________________________________________________________ PHOBIASsexual abuse, domestic violence) were constructed and used in log-linearanalyses modelling the relationship between such risk factors andpsychiatric disorder.The one-year prevalence of DSM-III-R anxietydisorders (panic disorder, agoraphobia, social phobia, simple phobias,generalized anxiety) was 23.8%.Close to half of the sample had experiencedclinically significant depression at some point during the anxiety episode,while only 7.2% had depression without anxiety.Panic disorder was mostlikely (67%), and simple phobias least likely (11%), to be associated withdepression.The time spent in anxiety (8.1% of the one-year periodpreceding the interview) was double the time spent in depression, andanxiety disorders were more often chronic than depression.Onsets ofanxiety disorders within an ongoing depressive episode were rare;however, onsets of depression among those with ongoing anxiety disorderwere common.The analysis of risk factors highlighted different mechanisms ofoperation for psychosocial factors in depression and anxiety.While adultlife adversity and low levels of social support were related to depression,vulnerability to anxiety was less influenced by current adversity or levelsof support and more by early adversity, constitutional factors, or both.About half of the women with anxiety disorder (particularly panicdisorder and agoraphobia) had experienced early adversity, whichremained significantly associated with anxiety after controlling for adultadversity.The study design allowed teasing out the separate contributions ofanxiety and depression to the commonly observed comorbidity of the twoconditions.The main contribution to comorbidity (44% of the total rate)resulted from the joint high prevalences of the two conditions, i.e.represented chance comorbidity.However, over 50% of the observedcomorbidity was non-chance, suggesting that factors other than childhoodand adult life adversity may play an important role.Although involvementof further psychosocial stressors could not be ruled out, the study suggestsan underlying common genetic liability, or a single neurodevelopmentalprocess, at the root of the comorbidity problem.My second example highlights the potential benefits from epidemio-logical studies of rare isolate populations that are relatively homogeneous,in both genetic and lifestyle respects.The Hutterites, a Protestant anabaptist sect founded in the 16th centuryby Jacob Hutter in Switzerland, are a genetic isolate with a high index ofconsanguinity resulting from a closed-in lifestyle, imposed by religiouspersecution and group migration that led them first to Russia and later onto the US and Canada, where they settled as small farming communities.The majority of the Hutterites (present number estimated at about 40 000)are the descendants of 89 individuals who formed a family at the end of EPIDEMIOLOGY OF PHOBIAS: COMMENTARIES _______________________________________ 83the 18th century.They represent an almost ideal founder population thathad experienced a relatively recent bottleneck, ensuring a high degree ofgenetic homogeneity.The medical and psychiatric profile of the Hutteriteswas first described in the 1950s by Eaton and Weil in a classic monographentitled Culture and Mental Disorders [5].The main finding of the study wasthe extremely low incidence of schizophrenia, which was hypotheticallyexplained as the result of sociogenetic selection: individuals with schizoidtraits or other schizophrenia-prone attributes were unlikely to adjust to thehighly collectivist ethos of the community and, hence, had low chances ofprocreation within the sect.A follow-up epidemiological study some 40years later [6] replicated the original finding of a low incidence of psychosesin the Hutterite communities, but it also revealed something that hadescaped the initial survey: an unusually high prevalence of neuroticdisorders, including anxiety and phobias.The prevalence rate of neuroticdisorders, at 86.7 per 1000, was more than twice the expected rate, based onthe general population of the area.Both cultural and genetic factors may be at work to produce thisphenomenon.While providing an extraordinary level of familial andcommunity support, the strict religious indoctrination, lifestyle regimenta-tion and conformity to tradition within the closely knit community may beconducive to excessive anxiety in many individual members with orwithout a specific genetic vulnerability.Such an interpretation would be inagreement with the findings of another population survey that in theOuter Hebrides [7] which revealed that the rates of chronic anxiety werehighest among the most socially integrated members of the community (e.g [ Pobierz całość w formacie PDF ]