Abstract
Background Visual height intolerance occurs when a visual stimulus causes apprehension of losing balance and falling from some height. Affecting one-third of the population, it has a broad spectrum of symptoms, ranging from minor distress to fear of heights, which is defined as a specific phobia. Specific phobias are associated with higher alcohol consumption. This has not been specifically shown for susceptibility to the more general visual height intolerance. Methods Representative case–control study nested within a population-based cross-sectional telephone survey to assess epidemiologically 1253 individuals ≥14 years, using a questionnaire on sociodemographic data, typical symptoms, precipitating visual stimuli, and alcohol drinking patterns (overall frequency of alcohol consumption, the daily quantities, and the motives). Results Individuals susceptible or nonsusceptible to visual height intolerance showed no significant differences in drinking patterns. The daily average alcohol consumption was slightly higher in persons susceptible to visual height intolerance (4.1 g/day vs. 3.7 g/day). Of those consuming alcohol, cases and controls reported on average consuming 2.3 glasses per day. The prevalence of visual height intolerance was insignificantly higher in the small minority of those drinking 2–3 times per week versus teetotalers. Conclusions Our study does not provide evidence that visual height intolerance – contrary to various specific phobias – is significantly associated with individual alcohol consumption patterns.
Keywords: Acrophobia, alcohol consumption, epidemiology, fear of heights, visual height intolerance
Introduction
The association of alcohol drinking patterns and anxiety disorders is well recognized. Evidence indicates that anxiety disorders may cause and aggravate alcohol intake and vice versa (Smail et al. 1984; Himle and Hill 1991; Lotufo-Neto and Gentil 1994; Allan 1995; Kessler et al. 1997; Kushner et al. 2000; Singh et al. 2005; Charriau et al. 2012). The relationship of phobic disorders, especially social anxiety, and alcohol consumption has been emphasized (Morris et al. 2005; Blumenthal et al. 2010; Schneier et al. 2010; Buckner and Matthews 2012). A large representative epidemiological survey in the United States (Stinson et al. 2007) revealed the comorbidity of alcohol abuse and specific phobias. However, patterns of comorbidity vary according to the subtypes of specific phobias (LeBeau et al. 2010; MacDonald et al. 2011); there is a higher comorbidity of animal, situational and blood/injury subtypes than of so-called environmental subtypes (Becker et al. 2007; Depla et al. 2008). Up to 30% of patients with fear of heights sometimes use medication or alcohol for relief (Stransky 1957; Menzies and Clarke 1995; Robinson et al. 2009). The observation by Curlee and Stern (1973) that alcoholics in a psychotherapy group often report fear of heights was not confirmed by others (Ruff et al. 1976) and does not allow generalization.
No systematic study has focussed on the relationship of fear of heights and daily alcohol consumption. Any such association would be relevant for both root cause analysis and the management of these patients. Investigations should take into account that besides the specific phobia fear of heights there is also a more frequent “nonphobic” fear of heights, which is best called “visual height intolerance” (Brandt et al. 2012a). Visual height intolerance occurs when a visual stimulus causes apprehension of losing one's balance and falling from some height but without typical symptoms of panic attacks. A recent cross-sectional representative epidemiological study of 3517 individuals reported that the life-time prevalence of visual height intolerance including fear of heights accounts for about one-third of the general population (Huppert et al. 2013). This is the only epidemiological study on “global” visual height intolerance which covered the entire spectrum of symptoms, beginning with a minor distressing height intolerance at one end, then more severe patterns, right up to symptoms of the specific phobia, fear of heights, at the other end. Available epidemiological studies deal with the specific phobia fear of heights (acrophobia) as classified by the ICD-10 (World Health Organization 1993) and DSM-IV TR (American Psychiatric Association 2000) criteria. The life-time prevalence for fear of heights lies between 3.1% and 5.3% (Agras et al. 1969; Curtis et al. 1998; Becker et al. 2007; Stinson et al. 2007; Depla et al. 2008; Oosterink et al. 2009; LeBeau et al. 2010); the life-time prevalence for visual height intolerance is 28% (Brandt et al. 2012b; Huppert et al. 2013).
In the current representative epidemiological study we were interested in how alcohol drinking patterns and the susceptibility to fear of heights and mild visual height intolerance are associated in the general population.
Material and Methods
Study design and data collection procedures
A case–control study nested within a population-based cross-sectional telephone survey was conducted. For the survey, a representative sample of individuals aged 14 and above was selected based on a three-stage sampling design. The multistratified, geographically based probability sampling of households allowed an additional random selection of defined targets.
A case was defined as any participant of the survey who reported having life-time visual height intolerance (answering yes to “Have you ever experienced visual height intolerance, an unpleasant feeling caused by visual exposure to heights?”). Controls were selected randomly from the group of participants who did not report ever having had any visual height intolerance. This approach was chosen to minimize selection bias of controls. The study was performed by trained interviewers.
Measures
The survey questionnaire asked about sociodemographic characteristics, typical symptoms, situations of occurrence, and alcohol consumption.
Presence or absence of visual height intolerance (status as case or control) was defined as outcome. Questions on alcohol consumption were related to the overall frequency of alcohol consumption, the daily quantities of consumed alcohol, and the motive for consuming alcohol, that is, consumption with the intention to relieve visual height intolerance and to cope with the fear-evoking situation. Only cases as defined above answered the latter question. Quantity was defined as glasses of beer, wine or sparkling wine and liquor. Alcohol consumption was calculated on the basis of the reported frequency of consumption and the number of glasses of alcoholic beverages consumed per day. One standard drink was defined as equivalent to 12 g of pure alcohol (World Health Organization 2004). The following categories for alcohol consumption were used: nondrinker, >0–6 g/day (>0–0.5 drink/day), >6–12 g/day (>0.5–1 drink/day), >12–24 g/day (>1–2 drinks/day), >24–60 g/day (>2–5 drinks/day), >60 g/day (>5 drinks/day). As only one person fell in the highest category, the upper two categories were subsumed under one. Heavy alcohol consumption was defined as 60 g/day for men and 30 g/day for women (World Cancer Research Fund/American Institute for Cancer Research 2007).
Sociodemographic characteristics, that is, age, sex, household size, income, occupation, education, and the presence or absence of self-reported fear or panic were used as covariates. Age was stratified into seven categories (<14–19, 20–29, 30–39, 40–49, 50–59, 60–69, 70, and above). Education was stratified into five categories (grade school without vocational training, grade school with vocational training, secondary school, postsecondary school (Abitur) and university, still attending school).
Statistical analysis
Means were used for continuous variables and percentages for categorical variables. Explorative t-tests and chi-square tests were applied for comparisons of individuals with symptoms of visual height intolerance and those without, as well as multiple logistic regression analyses to determine the association of alcohol consumption and visual height intolerance. A variable was a candidate for entrance into the regression model, if it had a P-value <0.20 in the bivariate test. To avoid colinearity, variables were selected for entering the multiple logistic models only if the Spearman correlation coefficient was <0.5.
When necessary to choose between two correlated variables, the variable with the stronger association with the dependent variable was entered into the model. As stepwise regression modeling may result in the selection of unstable subsets (Steyerberg et al. 2001), all candidate variables were included in the final models.
SAS statistical software was used for all analyses (V9.3, SAS Institute Inc. Cary, NC). Statistical significance was set at the conventional two-tailed 5% level.
As it had been hypothesized that the association of alcohol consumption and visual height intolerance might be different in persons reporting fear or panic, and that patterns of alcohol consumption might differ in women, the models were also analyzed stratified for self-reported fear/panic and for sex.
Results
Of a total of 2012 surveyed persons 582 (28.5%) reported a life-time prevalence of height intolerance (visual height intolerance cases, 61.7% women, mean age = 47.6, SD 17.5). Of the remaining 1430 persons without visual height intolerance 683 persons were randomly selected as controls (51.2% women, mean age = 51.2, SD 17.5). Thus, the sample consisted of 1265 persons; 1253 persons answered the questions on alcohol consumption (12 persons refused to answer these questions) (Table 1). Average alcohol consumption was 4.1 g/day for persons with visual height intolerance and 3.7 g/day for persons without visual height intolerance. The difference was not significant. One participant in the visual height intolerance group reported heavy alcohol consumption; no participant in the control group reported heavy alcohol consumption. The daily consumed quantities of alcohol corresponded approximately to data published by the Federal Office of Statistics (Bloomfield et al. 2008). Cases and controls did not differ in alcohol consumption, but in the frequency of alcohol consumption and the daily quantity. The majority in both groups claimed to drink alcohol once a month (30% in cases vs. 31% in controls), followed by two to three times a month (27% vs. 26%); only a small minority reported drinking four times a week or more often (7% vs. 10%). On average, of those consuming alcohol, cases and controls reported consuming 2.3 glasses per day. Three percent of cases reported that drinking alcohol alleviated symptoms of visual height intolerance.
Table 1.
Sociodemographic characteristics of cases (n = 582) and controls (n = 683)
Table | n | Height intolerance (cases) | No height intolerance (controls) | Total | P-value | |||
---|---|---|---|---|---|---|---|---|
n | % | n | % | n | % | |||
Alcohol consumption | 1206 | 582 | 45.4 | 683 | 53.3 | 100.0 | 0.2718 | |
nondrinker | 114 | 20.4 | 141 | 21.8 | 255 | 21.1 | ||
>0–6 g/day (>0–0.5 drink/day) | 290 | 52.0 | 344 | 53.1 | 634 | 52.6 | ||
>6–12 g/day (>0.5–1 drink/day) | 116 | 20.8 | 135 | 20.8 | 251 | 20.8 | ||
>12–24 g/day (>1–2 drinks/day) | 21 | 3.8 | 11 | 1.7 | 32 | 2.7 | ||
>24–60 g/day (>2–5 drinks/day) | 16 | 2.9 | 17 | 2.6 | 33 | 2.7 | ||
>60 g/day (>5 drinks/day) | 1 | 0.2 | 0 | 0.0 | 1 | 0.1 | ||
Drinking frequency | 0.0696 | |||||||
Never | 114 | 19.6 | 141 | 21.0 | 255 | 20.4 | ||
Once a month or less | 173 | 29.8 | 205 | 30.5 | 378 | 30.2 | ||
2–3× per month | 157 | 27.0 | 174 | 25.9 | 331 | 26.4 | ||
2–3× per week | 83 | 12.4 | 97 | 16.7 | 180 | 14.4 | ||
4× per week or more | 40 | 6.9 | 69 | 10.3 | 109 | 8.7 | ||
Fear or panic | 1265 | <0.0001 | ||||||
Never | 340 | 58.4 | 526 | 77.0 | 866 | 68.5 | ||
Age in years | 1265 | 0.0004 | ||||||
14–19 | 45 | 7.7 | 55 | 8.1 | 100 | 7.9 | ||
20–29 | 62 | 10.7 | 67 | 9.8 | 129 | 10.2 | ||
30–39 | 76 | 13.1 | 64 | 9.4 | 140 | 11.1 | ||
40–49 | 127 | 21.8 | 125 | 18.3 | 252 | 19.9 | ||
50–59 | 121 | 20.8 | 113 | 16.5 | 234 | 18.5 | ||
60–69 | 75 | 12.9 | 111 | 16.3 | 186 | 14.7 | ||
70+ | 76 | 13.1 | 148 | 21.7 | 224 | 17.7 | ||
Education | 1265 | 0.0008 | ||||||
Grade school without vocational training | 16 | 2.7 | 38 | 5.6 | 54 | 4.3 | ||
Grade school with vocational training | 124 | 21.3 | 192 | 28.1 | 316 | 25.0 | ||
Secondary school | 146 | 25.1 | 125 | 18.3 | 271 | 21.4 | ||
Abitur, university | 261 | 44.8 | 287 | 42.0 | 548 | 43.3 | ||
Still attending school | 35 | 6.0 | 41 | 6.0 | 76 | 6.0 | ||
Occupation | 1265 | 0.0125 | ||||||
Employed | 350 | 60.1 | 363 | 53.1 | 713 | 56.4 | ||
Sex | 1265 | 0.0002 | ||||||
Male | 223 | 38.3 | 333 | 48.8 | 556 | 44.0 |
N = 17 answered the question on visual height intolerance with “do not know” and are therefore not included. N = 12 refused to answer questions on alcohol consumption.
When covariates were controlled for, neither drinking frequency nor consumed quantity of alcohol were significantly associated with visual height intolerance; however, the prevalence of height intolerance was slightly higher in those drinking 2–3 times per week versus teetotalers. Female sex, age 20–59 versus 70 and over, higher education and self-reported presence of fear or panic were significantly associated with visual height intolerance (Table 2). Stratifying for fear/panic and for sex did not substantially change the results as to the individual alcohol consumption.
Table 2.
Results of multivariable adjusted model (n = 1253) predicting height intolerance (odds ratios >1 indicate higher risk for height intolerance)
Variable | Odds ratio | Lower CL | Upper CL |
---|---|---|---|
Female | 1.7 | 1.3 | 2.2 |
Age | |||
14–19 vs. 70+ years | 1.5 | 0.9 | 2.5 |
20–29 vs. 70+ years | 2.2 | 1.4 | 3.6 |
30–39 vs. 70+ years | 2.8 | 1.7 | 4.4 |
40–49 vs. 70+ years | 2.2 | 1.5 | 3.3 |
50–59 vs. 70+ years | 2.0 | 1.4 | 3.1 |
60–69 vs. 70+ years | 1.5 | 1.0 | 2.3 |
Alcohol consumption | |||
nondrinker vs. >24 g/day (>2 drinks/day) | 0.6 | 0.3 | 1.2 |
>0–6 g/day (>0–0.5 drink/day) vs. >24 g/day (>2 drinks/day) | 0.6 | 0.3 | 1.2 |
>6–12 g/day (>0.5–1 drink/day) vs. >24 g/day (>2 drinks/day) | 0.7 | 0.3 | 1.5 |
>12–24 g/day (>1–2 drinks/day) vs. >24 g/day (>2 drinks/day) | 1.5 | 0.5 | 4.3 |
Fear or panic | 2.6 | 2.0 | 3.3 |
Higher education (Abitur, university) | 1.6 | 1.2 | 2.2 |
CL, 95% confidence limit; d, day; g/day, gram alcohol per day.
Discussion
The life-time prevalence of visual height intolerance (28.5%) corresponded with findings of our first representative epidemiological study (28%) (Huppert et al. 2013). A significant association between daily alcohol consumption and global visual height intolerance could not be ascertained. There was merely a slightly higher prevalence in those persons who reported moderate, but frequent alcohol consumption (2–3 times a week) compared with those who did not consume any alcohol. The prevalence, however, was not increased in those persons with a greater drinking frequency of four times per week and more. Thus, this result should not be overemphasized. These results correspond to earlier reported lower associations of substance use disorders and environmental specific phobias compared with other specific phobias (Becker et al. 2007; LeBeau et al. 2010). The statistically low significant relationship of subclinical specific phobias and the subsequent onset of alcohol abuse or dependence which MacDonald et al. (2011) described seems contradictory; however, they do not specify the subtypes of specific phobias in their study.
Our failure to find an association of alcohol consumption and visual height intolerance similar to that of alcohol dependence and social anxiety may be due to the fact that height is a peristatic factor that can be easily avoided. Therefore, alcohol is probably not used as a self-medication to cope with expected fearful situations like individuals with anxiety disorders in the general population report (Kushner et al. 2000; Buckner and Matthews 2012) or as especially persons with social anxiety use it to lessen anxiety associated with anticipated specific social situations (Thyer and Curtis 1984; Robinson et al. 2009; Buckner and Matthews 2012). This negative association has consequences for the therapeutic management of persons with visual height intolerance. Therapeutic attention cannot be primarily directed to drinking patterns in contrast to social anxiety disorders (Morris et al. 2005). Treatment strategies should address behavioral aspects of visual height intolerance, for example, habituation by exposition, and improvement of balance control by gaze and locomotion strategies (Brandt et al. 1980). One should also consider that all participants of a qualitative study on visual height intolerance repeatedly reported safety (e.g., anticipatory and actual individual control of visual height stimuli) to be of great importance (Schäffler et al. 2013). These participants referred not only to a general idea of feeling safe but also to the relevance of balance aids such as balustrades, handrails, being on a rope, the quality of hiking shoes, and the importance of having prior experience with a trail.
Limitation
The major limitation in all studies of this kind is the “self-report of alcohol use”. Although research indicates that this method can deliver a valid index (Kenny and Grant 2007), there can also be some bias, because persons who drink in order to attenuate their symptoms might not be eager to acknowledge this and might underreport their consumption.
Conclusions
Our study does not provide evidence that visual height intolerance – contrary to various specific phobias – is significantly associated with individual alcohol consumption patterns.
Acknowledgments
The authors thank Judy Benson for copyediting the manuscript.
Conflict of interest
None declared.
References
- Agras S, Sylvester D, Oliveau D. The epidemiology of common fears and phobia. Compr. Psychiat. 1969;10:151–156. doi: 10.1016/0010-440x(69)90022-4. [DOI] [PubMed] [Google Scholar]
- Allan CA. Alcohol problems and anxiety disorders—a critical review. Alcohol Alcohol. 1995;30:145–151. [PubMed] [Google Scholar]
- American Psychiatric Association. Committee on nomenclature and statistics diagnostic and statistical manual of mental disorders. 4th ed. Washington, DC: American Psychiatric Press; 2000. text revision. [Google Scholar]
- Becker ES, Rinck M, Türke V, P Kause, R Goodwin, S Neumer, et al. Epidemiology of specific phobia subtypes: findings from the Dresden Mental Health Study. Eur. Psychiatry. 2007;22:69–74. doi: 10.1016/j.eurpsy.2006.09.006. [DOI] [PubMed] [Google Scholar]
- Bloomfield K, Kraus L, Soyka M. Gesundheitsberichterstattung des Bundes. Alkoholkonsum und alkoholbezogene Störungen. Berlin, Germany: Robert Koch-Institut; 2008. [Google Scholar]
- Blumenthal H, Leen-Feldner EW, Frala JL, Badour CL, Ham LS. Social anxiety and motives for alcohol use among adolescents. Psychol. Addict. Behav. 2010;24:529–534. doi: 10.1037/a0019794. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brandt T, Arnold F, Bles W, Kapteyn TS. The mechanism of physiological height vertigo. I. Theoretical approach and psychophysics. Acta Otolaryngol. 1980;89:513–523. doi: 10.3109/00016488009127169. [DOI] [PubMed] [Google Scholar]
- Brandt T, Benson J, Huppert D. What to call “non-phobic” fear of heights? Br. J. Psychiatry. 2012a;190:81. doi: 10.1192/bjp.190.1.81a. [Google Scholar]
- Brandt T, Strupp M, Huppert D. Height intolerance: an underrated threat. J. Neurol. 2012b;259:759–760. doi: 10.1007/s00415-011-6238-z. [DOI] [PubMed] [Google Scholar]
- Buckner JD, Matthews RA. Social impressions while drinking account for the relationship between alcohol-related problems and social anxiety. Addict. Behav. 2012;37:533–536. doi: 10.1016/j.addbeh.2011.11.026. [DOI] [PubMed] [Google Scholar]
- Charriau V, Elyakoubi M, Millet B, Drapier D, Robin D, Moirand R. Generalized anxiety disorder is under-recognized in clinical practice in patients with alcohol dependence in France. Alcohol. 2012;47:15–19. doi: 10.1016/j.alcohol.2012.08.008. doi: 10.1016/j.alcohol.2012.08.008. [DOI] [PubMed] [Google Scholar]
- Curlee J, Stern H. The fear of height s among alcoholics. Bull. Menninger Clin. 1973;37:615–623. [PubMed] [Google Scholar]
- Curtis GC, Magee WJ, Eaton WW, Wittchen HU. Specific fears and phobias. Epidemiology and classification. Br. J. Psychiatry. 1998;173:212–217. [PubMed] [Google Scholar]
- Depla MF, ten Have ML, van Balkom AJ, de Graaf R. Specific fears and phobias in the general population: results from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) Soc. Psychiatry Psychiatr. Epidemiol. 2008;43:200–208. doi: 10.1007/s00127-007-0291-z. [DOI] [PubMed] [Google Scholar]
- Himle JA, Hill EM. Alcohol abuse and the anxiety disorders: evidence from the Epidemiologic Catchment Area Survey. J. Anxiety Disord. 1991;5:237–245. [Google Scholar]
- Huppert D, Grill E, Brandt T. Down on heights? One in three has visual height intolerance. J. Neurol. 2013;260:597–604. doi: 10.1007/s00415-012-6685-1. [DOI] [PubMed] [Google Scholar]
- Kenny DT, Grant J. Reliability of self-report of health in juvenile offenders. Vulnerable Child Youth Stud. 2007;2:127–141. [Google Scholar]
- Kessler RC, Crum RM, Warner LA, Nelson CB, Schulenberg J, Anthony JC. Lifetime co-occurrence of DSM-III-R alcohol abuse and dependence with other psychiatric disorders in the National Comorbidity Survey. Arch. Gen. Psychiatry. 1997;54:313–321. doi: 10.1001/archpsyc.1997.01830160031005. [DOI] [PubMed] [Google Scholar]
- Kushner MG, Abrams K, Borchardt C. The relationship between anxiety disorders and alcohol use disorders: a review of major perspectives and findings. Clin. Psychol. Rev. 2000;20:149–171. doi: 10.1016/s0272-7358(99)00027-6. [DOI] [PubMed] [Google Scholar]
- LeBeau RT, Glenn D, Liao B, Wittchen HU, Beesdo-Baum K, Ollendick T, et al. Specific phobia: a review of DSM-IV specific phobia and preliminary recommendations for DSM-V. Depress. Anxiety. 2010;27:148–167. doi: 10.1002/da.20655. [DOI] [PubMed] [Google Scholar]
- Lotufo-Neto F, Gentil V. Alcoholism and phobic anxiety–a clinical-demographic comparison. Addiction. 1994;89:447–453. doi: 10.1111/j.1360-0443.1994.tb00925.x. [DOI] [PubMed] [Google Scholar]
- MacDonald R, Crum RM, Storr CL, Schuster A, Bienvenu QJ. Sub-clinical anxiety and the onset of alcohol use disorders: longitudinal associations from the Baltimore ECA follow-up, 1981-2004. J. Addict. Dis. 2011;30:45–53. doi: 10.1080/10550887.2010.531667. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Menzies RG, Clarke JC. Danger expectancies and insight in acrophobia. Behav. Res. Ther. 1995;33:215–221. doi: 10.1016/0005-7967(94)p4443-x. [DOI] [PubMed] [Google Scholar]
- Morris EP, Stewart SH, Ham LS. The relationship between social anxiety disorder and alcohol use disorders: a critical review. Clin. Psychol. Rev. 2005;25:734–760. doi: 10.1016/j.cpr.2005.05.004. [DOI] [PubMed] [Google Scholar]
- Oosterink F, Hoogstraten A, de Jongh J. Prevalence of dental fear and phobia relative to other fear and phobia types. Eur. J. Oral Sci. 2009;117:135–143. doi: 10.1111/j.1600-0722.2008.00602.x. [DOI] [PubMed] [Google Scholar]
- Robinson J, Sareen J, Cox BJ, Bolton J. Self-medication of anxiety disorders with alcohol and drugs: results from a nationally representative sample. J. Anxiety Disord. 2009;23:38–45. doi: 10.1016/j.janxdis.2008.03.013. [DOI] [PubMed] [Google Scholar]
- Ruff CF, Ayers JL, Simon SE, Templer DI. The fear of heights among alcoholics: additional data relevant to the Curlee and Stern study. Bull. Menninger Clin. 1976;40:162–182. [PubMed] [Google Scholar]
- Schäffler F, Müller M, Huppert D, Brandt T, Tiffe T, Grill E. Psychosocial factors and consequences of visual height intolerance: a qualitative study. Qual. Life Res. 2013 doi: 10.1007/s11136-013-0506-6. In press. [DOI] [PubMed] [Google Scholar]
- Schneier FR, Foose TE, Hasin DS, Heimberg RG, Liu S-M, Grant BF, et al. Social anxiety disorder and alcohol use disorder co-morbidity in the National Epidemiologic Survey on Alcohol and Related Conditions. Psychol. Med. 2010;40:977–988. doi: 10.1017/S0033291709991231. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Singh NH, Sharma SG, Paswth AM. Psychiatric co-morbidity among alcohol dependants. Indian J. Psychiatry. 2005;47:222–224. doi: 10.4103/0019-5545.43058. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smail P, Stockwell T, Canter S, Hodgson R. Alcohol dependence and phobic anxiety states. I. A prevalence study. Br. J. Psychiatry. 1984;144:53–57. doi: 10.1192/bjp.144.1.53. [DOI] [PubMed] [Google Scholar]
- Steyerberg EW, Eijkemans MJ, Harrell FE, Jr, Habbema JD. Prognostic modeling with logistic regression analysis: in search of a sensible strategy in small data sets. Med. Decis. Making. 2001;21:45–56. doi: 10.1177/0272989X0102100106. [DOI] [PubMed] [Google Scholar]
- Stinson F, Dawson D, Chou S, Smith S, Goldstein RB, JuneRuan W, et al. The epidemiology of DSM-IV specific phobia in the USA: result from the National Epidemiologic Survey on Alcohol and Related Conditions. Psychol. Med. 2007;37:1047–1059. doi: 10.1017/S0033291707000086. [DOI] [PubMed] [Google Scholar]
- Stransky E. The phenomenon of psychological border areas; observations and thoughts on the problem of phobias and especially of height vertigo (Über das Geschehen an seelischen Nahtstellen. Beobachtungen und Gedanken in Anlehnung an die Problematik der Phobien und besonders des Höhenschwindels) Wien. Med. Wochenschr. 1957;107:912–917. [PubMed] [Google Scholar]
- Thyer BA, Curtis GC. The effects of ethanol intoxication on phobic anxiety. Behav. Res. Ther. 1984;22:599–610. doi: 10.1016/0005-7967(84)90122-0. [DOI] [PubMed] [Google Scholar]
- World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. Washington, DC: AICR; 2007. [Google Scholar]
- World Health Organization. The ICD-10 classification of mental and behavioral disorders, clinical description and diagnostic guidelines. Geneva, Switzerland: WHO; 1993. [Google Scholar]
- World Health Organization. Department of mental health and substance abuse. Geneva, Switzerland: World Health Organization; 2004. [Google Scholar]