Friday, March 22, 2013

Pain Strongly Influenced by Anxiety, Depression

Chronic PainIn prior research, migraine headache has been reported to frequently occur in conjunction with other pain conditions, along with an observation that multiple pain conditions in general tend to cluster within many patients. A new study examined the important role of anxiety, depression, or both mental disorders in migraine and the relationship with 6 other, non-headache, chronic pain conditions.

Taking migraine headache as a starting point — since it is among the best-studied pain disorders in the context of psychiatric comorbidity — researchers in The Netherlands constructed a longitudinal cohort study to compare occurrences of migraine with 6 other persistent pain locations: back, neck, orofacial, abdomen, joints, and chest. Of special interest was the relationship of these disorders with anxiety, depression, or both in these patients.

Lannie Ligthart — from the Department of Biological Psychology, VU University, Amsterdam — and colleagues, writing in an early online edition of the Journal of Pain, report enrolling in their study 2,981 participants from the Netherlands Study of Depression and Anxiety (NESDA). Patients were from a number of clinical settings and comprised persons with either a) current anxiety and/or depression, b) remitting anxiety and/or depression (ie, prior history but not presently evident), and c) controls without a mental health disorder.

Subjects were 42 years of age on average (range 18-65) and a majority (66%) were female. All participants had a baseline interview to assess physical and mental health, and a 2-year followup assessment (at which 85%, or 2,596 subjects, were available).

Results indicated a high prevalence (78%) of psychiatric comorbidity overall: 31% of participants had either an anxiety or a depressive disorder, and 26% had a combination of both. Another 21% of participants had a remitted diagnosis of either anxiety or depression.

Scores for anxiety and depression (A/D) were closely associated with migraine status, with increasing A/D scores corresponding to headache severity. This confirmed the association between migraine and A/D.

Compared with individuals reporting no pain in the prior 6 months, participants with any of the 6 non-headache pain types also had higher mean anxiety and/or depression scores. Along with that, a greater number of reported pain locations was associated with higher mean A/D scores. Reports of no pain (6% of subjects) or only 1 type of pain (13%) were relatively rare; the vast majority of participants (81%) reported ongoing pain in more than 1 region of the body.


In the figure (above) sex- and age-adjusted odds ratios (ORs) are shown for pain reports in each body location by anxiety and/or depression (A/D) status [vertical error bars are assumed to represent 95% confidence intervals, although this was not clearly stated in the report]. All types of pain were associated significantly with current anxiety or depression (ie, error bars do not cross 1.0), and most strongly with combined anxiety and depression (columns at right).

The associations were considerably weaker and commonly nonsignificant for remitted A/D. The strongest associations were observed between A/D and migraine (strictly defined), neck pain, and chest pain. Probable migraine and mild nonmigrainous headache were less strongly associated with A/D than strict migraine, possibly reflecting stronger comorbidity with A/D in patients with more severe headaches. The associations with A/D were weakest for back and joint pain, but still statistically significant.

In sum, anxiety and/or depression was consistently associated with pain in all measured locations. Migraine was associated with and predictive of pain in all other anatomical sites, but these correlations weakened substantially after correction for A/D severity. This suggests that a considerable part of the comorbidity of migraine and other types of pain may be explained by A/D.

The findings emphasize the importance of accounting for anxiety and/or depression in studies of pain comorbidity as well as during clinical pain management. The researchers advise that, “Multiple pain symptoms associated with a severe anxiety or depressive disorder may require a different interpretation and treatment approach than pain symptoms that arise in the absence of psychiatric symptoms.”

COMMENTARY: A very recent Pain-Topics UPDATE [here] described a new study by Yoon et al. [2013] in Germany that found a close association of headache — either migraine or tension-type headache — with lower-back pain. And, an increased frequency of low-back pain correlated with having chronic headache (≥15 days/month). However, of some importance, that study did not assess or account for possible influences of comorbid anxiety or depression.

This present study by Ligthart et al. suggests that the link between headache and low-back pain might have been mediated by anxiety and/or depression (A/D). Also, this present study found a correspondence over time: longitudinally, the researchers observed a modest but significant correlation between changes in severity of A/D and changes in the number of chronic pain sites. However, cause-effect relationships cannot be inferred from such data, and it is not known which came first; changes in pain or changes in A/D status.

Another important distinction is that the study by Yoon et al. was population-based — ie, the study sample was drawn randomly from the general population — whereas, this present study by Ligthart et al. was clinic-based, focusing on patients in primary care or mental health settings. This may account for the high prevalence of psychiatric comorbidity in this present study and challenges the generalizability of its findings to the population at large or even other types of clinical settings.

Ligthart and colleagues also had no information regarding possible trauma or underlying disease that could have accounted for pain in multiple locations, and this might be a confounding factor. Furthermore, their study only considered the most common anxiety or depressive disorders; so, other psychiatric diagnoses that might affect pain status, such as PTSD (posttraumatic stress disorder), may have been present but not assessed.

The observations in this study of significant associations between A/D and pain disorders are not entirely new to the pain literature. For example, Ligthart and colleagues acknowledge that studies in patients with fibromyalgia and irritable bowel syndrome have reported anxiety and/or depression comorbidity. Still, this present study is a good reminder that multiple chronic pain disorders, or sites of pain, may tend to cluster within individuals, and strategies directed only toward resolving physical complaints, without taking into consideration mental health factors, may be addressing only part of the problem — perhaps, not the most important part in some patients.

> Ligthart L, Gerrits MMJG, Boomsma DI, et al. Anxiety and Depression Are Associated With Migraine and Pain in General: An Investigation of the Interrelationships. J Pain. 2013; online ahead of print [
abstract here].
> Yoon M-S, Manack A, Schramm S, et al. Chronic migraine and chronic tension-type headache are associated with concomitant low back pain: Results of the German Headache Consortium study. PAIN. 2013(Mar);154(3): 484–492 [
abstract here].

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