Abstract
Dear Sir
Peres and colleagues recently reported an interesting case series of nine new daily-persistent headache (NDPH) patients who had anxiety symptoms coincident with headache onset (1). In their report, they commented that “NDPH has never been linked to psychiatric conditions, and never been studied extensively for a possible association”. There is a lack of available data regarding psychiatric comorbidity in NDPH patients, but I would like to highlight a recent report and provide some additional data to add to the limited evidence on the association.
In our recent cohort of 71 NDPH patients, we reported some data on comorbid psychiatric disease (2). NDPH was diagnosed according to revised criteria that were also applied by Peres et al. (1), which did not restrict the diagnosis to only those patients lacking migraine features, a criteria that has gained significant support (3,4). NDPH patients commonly had a self-reported history of anxiety disorder (33.8%), depression (35.2%), or one of the two disorders (50.7%). Interestingly, two patients experienced NDPH onset while antidepressant medications were being tapered.
A subset of our patients (n = 37) completed the patient health questionnaire (PHQ-9), a validated screen for major depression (5). Based on PHQ-9 scores at the time of their first clinic visit, NDPH patients were determined to have minimal (37.8%), mild (27.0%), moderate (21.6%), moderately severe (8.1%) or severe (5.4%) depression.
In data that has not yet been reported, this same subset of 37 patients also simultaneously completed the generalized anxiety disorder questionnaire (GAD-7), a validated screen for generalized anxiety disorder (GAD) (6). Based on GAD-7 scores, NDPH patients were determined to have minimal (54.1%), mild (24.3%), moderate (8.1%) or severe (13.5%) anxiety.
Excluding the ‘minimal’ category using thresholds of PHQ-9 score >4 and GAD-7 score >4, 62.2% had some degree of depression and 45.9% had some degree of anxiety. Conversely, 32.4% of the NDPH patients had neither depression nor anxiety. Not unexpectedly, depression and anxiety scores trended fairly well together (r = 0.68, Pearson correlation coefficient).
As this cohort represents only NDPH patients from a single tertiary headache center, these estimates of psychiatric comorbidity may be overestimates of true depression and anxiety of NDPH patients in the population, as the more severely disabled patients tend to seek help or be referred to tertiary care.
An important question that remains unanswered is whether premorbid depression or anxiety is an important risk factor for the development of NDPH, or is simply a comorbidity acquired after the presence of a chronic, debilitating, painful disorder. Anxiety and depression have recently been confirmed to be risk factors for incident chronic migraine (7,8), and chronic migraine patients are much more likely to have comorbid depression and anxiety than episodic migraine patients (9).
The difficulties in determining the psychiatric risk factors for NDPH are that patients either present or are referred to specialists well after headache onset, and perhaps recall bias exists in underestimating premorbid depression and anxiety. Epidemiological studies of NDPH are not readily feasible, based on the disorder being quite rare in the population, with a 1-year prevalence ranging from 0.03% (10) to 0.1% (11). Future questions may be answered by a multi-center collaboration such as the effort currently being spearheaded by the American Migraine Foundation.