Abstract
Dear Sir In addition to those studies examining psychiatric comorbidity in migraine recently reviewed by Radat and Swendsen (1), I would like to draw your readers’ attention to the results of a further study of importance. The Dunedin Multidisciplinary Health and Development Study is a longitudinal investigation of the health and behaviour of a birth cohort of children born in Dunedin (population ≈ 120 000), New Zealand between 1 April 1972 and 31 March 1973 (2). Study participants have been comprehensively assessed on a wide variety of psychological and medical measures at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26, and most recently at age 32 years. The rate of attrition from the study has been extremely low, with 96.2% (n = 980) of the living sample available for the assessment at age 26 (1998–1999).
Prospective longitudinal data collected during this study have been used to examine the childhood correlates of adult headache diagnoses (3, 4). The headache status of subjects at age 26 was determined via face-to-face structured interview with a registered nurse or medical practitioner. Questions on headache characteristics were based on the 1988 International Headache Society classification criteria, and review of medical history was used to exclude secondary headache disorders.
Following adjustment for sex and childhood/maternal history of headache, the likelihood of having migraine at age 26 years was found to be significantly increased among subjects with high anxiety ratings aged 5–9 (worry/fearful subscale of the Rutter Child Behaviour Scales), odds ratio (OR) 1.3, 95% confidence interval (CI) 1.03, 1.67; high anxiety levels aged 13 and 15 (anxiety scale of the Revised Behaviour Problem Checklist), OR 1.4, 95% CI 1.06, 1.80; high stress reactivity personality trait at the age of 18 (stress reaction subscale of Multidimensional Personality Questionnaire), OR 1.4, 95% CI 1.06, 1.76; and DSM-III-R-defined anxiety disorders at age 18 and 21, OR 1.9, 95% CI 1.11, 3.29 (3). These findings were specific to migraine and were not observed in association with an adult diagnosis of tension-type headache (TTH). The observations could represent either a causal relationship between anxiety and incident migraine, or reflect a shared underlying pathophysiology with age-specific onset of anxiety and migraine. The results give further weight to the suggestion that migraine should be a headache subtype of particular interest to psychiatrists (5).
Results have also been published on the relationships between recurrent childhood (<12 years old) headache, subjectively perceived stress (‘feel bad’ scale) at age 15, and headache subtypes diagnosed at age 26 years (4). Subjects with a history of childhood headache were 1.4 (95% CI 1.0, 1.8) times more likely to report moderate stress, and 1.5 (95% CI 1.1, 1.9) times more likely to report high stress in mid adolescence than those with no history of childhood headache. In addition, subjects who reported high stress levels at age 15 were two to three times more likely to be diagnosed with migraine or migraine + TTH at age 26 than subjects who did not.
The associations between stress, personality traits, and psychiatric disorder and migraine reported by the Dunedin study should not be overlooked, as it is the most methodologically rigorous cohort study available. It is the only study to use a complete birth cohort, and has both the longest follow-up period and the lowest attrition rate. Subject assessments occurred at frequent intervals using face-to-face structured interviews and operationalized diagnostic criteria. Psychopathology was examined utilizing both categorical and dimensional symptom measures. In addition, as subjects are now entering the peak risk period for the development of both migraine and major depressive disorder, further information on the chronological relationship between these disorders and the risk factors associated with their development may be forthcoming.