Prevalence of new daily persistent headache in the general population. The Akershus study of chronic headache

The aim of the present study was to investigate the prevalence of new daily persistent headache (NDPH) in the general population, and compare the clinical characteristics of NDPH and chronic tension-type headache (CTTH). This is a population-based cross-sectional study. A random sample of 30 000 persons aged 30–44 years was drawn from the population of Akershus County, Norway. A postal questionnaire was screened for chronic headache. Those ( n  = 633) with self-reported chronic headache within the last month and/or year were invited to an interview and examination by a neurological resident. A follow-up interview was conducted after 1.5–3 years. The headaches were diagnosed according to the International Classification of Headache Disorders, 2nd edn and relevant revisions. The response rate of the questionnaire was 71% and the participation rate of the interview was 74%. Four persons, three men and one woman, had NDPH. The overall 1-year prevalence of NDPH was 0.03%. The clinical characteristics of NDPH and CTTH were similar, except for the sudden onset in NDPH. Three of the four persons with NDPH had medication overuse. Follow-up disclosed that the symptomatology of NDPH is not unchangeable, since two persons had improvement of their NDPH. NDPH is rare and occurs in one of 3500 persons from the general population of 30–44-year-olds. It is often associated with medication overuse.     

Chronic daily headache in children and adolescents

OBJECTIVE: To describe the clinical features of children with chronic daily headache (CDH) and examine the usefulness of the International Classification of Headache Disorders-II. BACKGROUND: Few data are available on chronic daily headache and analgesic overuse in children and adolescents and there are no specific criteria for headache in children. METHODS: We retrospectively reviewed all charts of 79 children and adolescents (<16 years) with headache on > or =15 days/month presenting to the outpatient clinic of the Department of Neurology of the Leiden University Medical Center between 1994 and 2001. We classified their headaches according to the International Classification of Headache Disorders-II. RESULTS: Fifty-seven (72%) children had chronic daily headache for more than 6 months, with a duration of more than 4 hours a day in 60% of them. Quality, severity, and location of pain varied. Sixty patients (76%) used analgesics, 10 patients more than one type. Thirteen patients (16%) used analgesics daily. In one-third of patients, headache led to frequent school absenteeism and sleeping problems. Twenty-eight (35%) patients could be classified, 17 patients (22%) as chronic tension-type headache, 5 patients (6%) as chronic migraine, and 6 patients (8%) as probable medication overuse headache. Fifteen patients (19%) did not fit into any category and 36 (46%) could not be classified due to insufficient data. CONCLUSIONS: Chronic daily headache in children is a serious disorder. A relatively large number of patients overuse medication and it leads to frequent school absenteeism and sleeping problems. It remains difficult to classify their headaches with the new criteria for headache disorders.     

Chronic migraine and medication overuse headache: clarifying the current International Headache Society classification criteria

Despite the recent advances in the understanding and classification of the chronic daily headaches, considerable controversy still exists regarding the classification of individual headaches, including chronic migraine (CM) and medication overuse headache (MOH). The original criteria, published in 2004, were difficult to apply to most patients with these disorders and were subsequently revised, resulting in broader clinical applicability. Nonetheless, they remain a topic of debate, and the revisions to the criteria have further added to the confusion. Even some prominent headache specialists are unsure which criteria to use. We aimed to explain the nature of the controversies surrounding the entities of CM and MOH. A clinical case will be used to illustrate some of the problems faced by clinicians in diagnosing patients with chronic daily headache.     

Chronic frequent headache in the general population: prevalence and associated factors

We studied the prevalence and short-term natural course of chronic frequent headache (CFH) in the general population and identified risk factors. In the Netherlands everyone is registered at a single general practice. We sent questionnaires to all persons (n = 21 440) aged 25-55 years, registered at 16 general practices. We compared the characteristics of 177 participants with CFH (>14 headache days/month for >3 months) with 141 participants with infrequent headache (1-4 days/month) and 526 without headache (<1 day/month). The prevalence of CFH was 3.7% [95% confidence interval (CI) 3.4, 4.0]. In 5 months, 12% showed a clinically relevant decrease to <7 days/month. In both headache groups 70% were women vs. 41% in the group without headache. Compared with the group with infrequent headache, the CFH group had more subjects with low educational level [35% vs. 11%; odds ratio (OR) 4.3, 95% CI 2.3, 7.8], medication overuse (62% vs. 3%; OR 38.4, 95% CI 13.8, 106.9), sleeping problems (44% vs. 8%; OR 8.1, 95% CI 3.6, 18.1), a history of head/neck trauma (36% vs. 14%; OR 4.0, 95% CI 2.2, 7.1), high scores on the General Health Questionnaire (62% vs. 34%; OR 2.7, 95% CI 1.3, 3.6) and more smokers (45% vs. 19%; OR 3.1, 95% CI 1.9, 5.3). We conclude that headache frequency fluctuates. CFH is common and associated with overuse of analgesics, psychopathology, smoking, sleeping problems, a history of head/neck trauma and low educational level. Female sex is a risk factor for headache, not for chronification of headache.     

Medications associated with probable medication overuse headache reported in a tertiary care headache center over a 15-year period

OBJECTIVES: To evaluate the substances associated with medication overuse headache (MOH) in a headache center, over the course of the past 15 years. BACKGROUND: The acute treatment of migraine has substantially changed over the past 15 years, and therefore, the substances associated with MOH may have changed as well. METHODS: We randomly reviewed charts of subjects seen during the years of 2005, 2000, 1995, and 1990, to identify substances associated with MOH. Since the criteria proposed by the second edition of the International Classification of Headache Disorders require causal attribution, demonstrated by improvement after withdrawal (and this was not assessed in this study), herein we refer to probable MOH (PMOH). We contrasted the substances associated with PMOH over the studied years. RESULTS: Our sample consists of 1200 individuals, 300 per year of interest. The proportions of subjects with a diagnosis of PMOH remained stable over the years, varying from 64% of all cases seen in the center in 1990, to 59.3% in 2005. We found a significant decrease in the relative frequency of probable ergotamine overuse headache (from 18.6% to 0%, P < .0001), and in probable combination analgesic overuse headache (from 42.2% to 13.6%, P < .0001). The differences were not significant for opioid overuse headache. The relative frequency increased significantly for the triptans (from 0% to 21.6%, P < .0001), simple analgesics (from 8.8% to 31.8%, P < .05), and for combinations of acute medications (from 9.8% to 22.7%, P = .01). CONCLUSION: While overuse of acute medications remains an important problem in the tertiary care arena, the substances associated with the overuse have dramatically changed over the past 15 years. Educational initiatives should emphasize that the newer specific acute migraine medications (triptans) may also be associated with PMOH.     

Outcome of medication overuse headache after abrupt in-patient withdrawal

One hundred and one patients suffering from chronic daily headache (CDH) and medication overuse were treated, in an in-patient setting, with abrupt discontinuation of the medication overused, intravenous hydrating, and intravenous administration of benzodiazepines and ademetionine. The mean time to CDH resolution was 8.8 days. The in-patient withdrawal protocol used was effective, safe and well tolerated. There was a trend for a shorter time to CDH resolution in patients who overused triptans (P=0.062). There was no correlation between time to CDH resolution and either the type of initial primary headache or duration of medication abuse, whereas time to CDH resolution was related to daily drug intake (P=0.01). In multiple regression analysis, daily drug intake, age and type of medication overused were independent predictors of time to CDH resolution. At 3-months' follow-up, no patient had relapsed and was again overusing symptomatic medications.     

Chronic daily headache with medication overuse: a randomized follow-up by neurologist or PCP

Several studies have shown the benefit of withdrawal therapy when medication overuse headache (MOH) is suspected. Our aim was to compare the effect of withdrawal therapy in patients followed by a neurologist (group A, n  = 42) and a primary care physician (PCP) (group B, n  = 38). Patients were randomized to A or B, and follow-up was at 3, 6 and 12 months. Calculated mean headache (MH at 6 months + MH at 12 months)/2 (primary end-point) was similar; A 1.04 (0.87, 1.21) and B 1.02 (0.82, 1.21) ( P  = 0.87). The number of patients with 50% improvement of headache days was also similar; 14/42 in group A vs. 12/34 in B ( P  = 0.86) at 3 months, 15/42 vs. 11/33 ( P  = 0.83) at 6 months and 15/42 vs. 14/38 ( P  = 0.92) at 12 months. Days without headache during the last 9 months of follow-up were 123 (96, 150) in group A and 137 (112, 161) in B ( P  = 0.62). After 3 months one-third were classified as MOH. Patients with MOH improved similarly in group A and B, and so did patients without MOH. Within 1 year 7/42 in A and 9/38 in B had recurrent medication overuse ( P  = 0.43). In summary, there were no significant differences in follow-up results between the two groups.     

Chronic daily headache in Taipei, Taiwan: prevalence, follow-up and outcome predictors

We conducted a two-stage population-based headache survey among subjects aged > or = 15 in Taipei, Taiwan. Subjects with chronic daily headache (CDH) in the past year were identified, interviewed and followed-up. CDH was defined as a headache frequency > 15 days/month, with a duration > 4 h/day. Of the 3377 participants, 108 (3.2%) fulfilled the criteria for CDH, with a higher prevalence in women (4.3%) than men (1.9%). TM was the most common subtype (55%), followed by CTTH (44%). Thirty-four per cent of the CDH subjects overused analgesics. At the 2-year follow-up, 35% of the CDH subjects still had CDH. The significant predictors for persistent CDH at follow-up included: older age ( > or = 40 years) (RR = 2.4), CDH onset after 32 years (RR = 1.8), CDH duration > or = 6 years (RR = 2.0), medication overuse (RR = 1.8), and "daily" headache (RR = 2.1). We found that CDH is not uncommon in the community and its prevalence is similar among different populations. Older subjects and those with medication overuse may have a more protracted course of illness.     

Chronic daily headache in a primary care population: prevalence and headache impact test scores

BACKGROUND: Population-based surveys estimate the prevalence of chronic daily headache (CDH) in the general community to be approximately 4%. The prevalence of CDH among patients seen in the primary care setting in the United States, however, is unknown. PURPOSE: To estimate the prevalence and associated burden of suffering of CDH in a primary care patient population. METHODS: Cross-sectional survey of a randomly selected sample of 1500 adult patients in an academic Family Medicine Center was done. Outcome measures include self-reported headache frequency and Headache Impact Test scores. RESULTS: Completed questionnaires were returned by 853 (57%) patients. The mean age of respondents was 49 years (SD = 16), with a range of 18 to 94 years. Two hundred ninety-six (58%) patients reported having had 1 or more severe headaches in the past month. Seventy-four (9%) patients reported a frequency of headache consistent with CDH, defined as the occurrence of headache 15 or more days in the past month. Twenty-four patients (32%) with CDH either believed that none of their doctors know that they experienced headaches or were not sure if their doctors were aware of their headaches, and 21 (28%) reported that they have not needed a doctor's care for their headaches. CONCLUSIONS: The prevalence of CDH is greater among a primary care patient population compared to the general community. A substantial proportion of patients with CDH do not bring their headaches to the attention of their health-care providers. In light of the advances in the development of effective medications for migraines and the growing body of evidence implicating medications as a contributing cause of CDH, it may be appropriate to encourage patients to inform their health-care providers about their headaches and to encourage providers to identify patients with frequent headaches.     

Chronic daily headache: a scientist's perspective

Certain features of chronic daily headache, namely, increased headache frequency, expansion of headache area, and cutaneous allodynia, may imply sensitization of central nociceptive neurons in the trigeminal pathway. Repetitive activation of the trigeminal nerve can lead to a biologic and functional change in trigeminal nucleus caudalis neurons, characterized by a decrease in nociceptive threshold and receptive field expansion. Suppression of the endogenous pain control system can facilitate the process of central sensitization. Evidence of such suppression in patients with chronic daily headache includes decreased platelet serotonin, up-regulation of 5-HT2A receptors, increased platelet nitric oxide production, and increased levels of substance P and nerve growth factor in the cerebrospinal fluid. Results from a number of animal experiments have indicated that chronic analgesic exposure leads to changes in serotonin content and density of 5-HT2A receptors in the central nervous system. This plasticity of the serotonin-dependent pain control system may accelerate the process of sensitization; a biologic outcome that is expressed clinically by the development of chronic daily headache associated with analgesic overuse.     

Chronic daily headache in children and adolescents presenting to tertiary headache clinics

BACKGROUND: Adults with chronic daily headache often describe a transformation from episodic migraine and partial retention of migrainous features. Although chronic daily headache has not been investigated as carefully in the pediatric population, one study showed a predominance of coexisting daily headache and episodic migraine, without a clear history of transformation. OBJECTIVE: To identify the clinical features of chronic daily headache in children and adolescents, to evaluate the efficacy of current headache classification criteria, and to compare the features of coexistent daily and episodic headaches so as to determine whether they represent separate syndromes or different stages in the "transformation" process. DESIGN: We surveyed 189 consecutive patients, 18 years of age or younger, who presented for initial evaluation of daily or near daily headache at one of 9 tertiary headache clinics. Data were collected in semistructured interviews employing a standard questionnaire and analyzed using Statistical Analysis Systems and Stata statistical software computer programs. RESULTS: Of the patients enrolled, 70% were female and 87% were white. Mean age was 13.0 +/- 3.1 years. Male gender was associated with a higher degree of reported disability. A family history of headache (typically migraine) was described in 79%. Use of nonsteroidal anti-inflammatory drugs 5 days per week or more was reported by 44% of patients. The International Headache Society (IHS) criteria failed to classify 64% of patients and criteria proposed by Silberstein et al failed to classify 31% of patients. Participating physicians misclassified patients according to criteria of the IHS and Silberstein et al in one third of cases. Nearly one quarter of patients reported two separate headache types with distinguishing characteristics. "Baseline" headache was present 27.3 +/- 4.1 days per month with a mean pain intensity of 5.9 +/- 2.1 on a 10-point scale. Superimposed episodic headache occurred 4.7 +/- 3.8 days per month with a mean pain intensity of 8.4 +/- 1.4, and was more often accompanied by other migrainous symptoms. After logistic regression to control for pain intensity, the only statistically significant difference between the two headache types was a lower prevalence of tension-type head pain with the superimposed headache. CONCLUSIONS: Our data suggest that rather than having two coexistent headache types, children and adolescents with chronic daily headache have a single syndrome that, in many cases, will paroxysmally worsen and gather migrainous features.     

Prednisone vs. placebo in withdrawal therapy following medication overuse headache

This proof-of-concept study evaluated the efficacy of prednisone for the treatment of withdrawal symptoms in patients with medication overuse headache (MOH) in a randomized, placebo-controlled, double-blind design. Twenty patients were randomized and underwent in-patient withdrawal therapy. The total number of hours with severe or moderate headache within the first 72 and 120 h was significantly lower in the prednisone group. The results show that prednisone might be effective in the treatment of medication withdrawal headache.     

Transformed migraine and medication overuse in a tertiary headache centre--clinical characteristics and treatment outcomes

Studies suggest that a substantial proportion of headache sufferers presenting to headache clinics may overuse acute medications. In some cases, overuse may be responsible for the development or maintenance of a chronic daily headache (CDH) syndrome. The objectives of this study are to evaluate patterns of analgesic overuse in patients consulting a headache centre and to compare the outcomes in a group of patients who discontinued medication overuse to those of a group who continued the overuse, in patients with similar age, sex and psychological profile. We reviewed charts of 456 patients with transformed migraine (TM) and acute medication overuse defined by one of the following criteria: 1. Simple analgesic use (>1000 mg ASA/acetaminophen) > 5 days/week; 2. Combination analgesics use (caffeine and/or butalbital) > 3 tablets a day for > 3 days a week; 3. Opiate use > 1 tablet a day for > 2 days a week; 4. Ergotamine tartrate use: 1 mg PO or 0.5 mg PR for > 2 days a week. For triptans, we empirically considered overuse > 1 tablet per day for > 5 days per week. Patients who were able to undergo detoxification and did not overuse medication (based on the above definition) after one year of follow-up were considered to have successful detoxification (Group 1). Patients who were not able to discontinue offending agents, or returned to a pattern of medication overuse within one year were considered to have unsuccessful detoxification (Group 2). We compared the following outcomes after one year of follow-up: Number of days with headache per month; Intensity of headache; Duration of headache; Headache score (frequency x intensity). The majority of patients overused more than one type of medication. Numbers of tablets taken ranged from 1 to 30 each day (mean of 5.2). Forty-eight (10.5%) subjects took >10 tablets per day. Considering patients seen in the last 5 years, we found the following overused substances: Butalbital containing combination products, 48%; Acetaminophen, 46.2%; Opioids, 33.3%; ASA, 32.0%; Ergotamine tartrate, 11.8%; Sumatriptan, 10.7%; Nonsteroidal anti-inflammatory medications other than ASA, 9.8%; Zolmitriptan, 4.6%; Rizatriptan, 1.9%; Naratriptan, 0.6%. Total of all triptans, 17.8%. Of 456 patients, 318 (69.7%) were successfully detoxified (Group 1), and 138 (30.3%) were not (Group 2). The comparison between groups 1 and 2 after one year of follow-up showed a decrease in the frequency of headache of 73.7% in group 1 and only 17.2% in group 2 (P < 0.0001). Similarly, the duration of head pain was reduced by 61.2% in group 1 and 14.8% in group 2 (P < 0.0001). The headache score after one year was 18.8 in group 1 and 54 in group 2 (P < 0.0001). A total of 225 (70.7%) successfully detoxified subjects in Group 1 returned to an episodic pattern of migraine, compared to 21 (15.3%) in Group 2 (P < 0.001). More rigorous prescribing guidelines for patients with frequent headaches are urgently needed. Successful detoxification is necessary to ensure improvement in the headache status when treating patients who overuse acute medications.     

Chronic daily headache in childhood and adolescence: clinical aspects and a 4-year follow-up

Chronic daily headache (CDH) represents a challenge in clinical practice and the scientific field. CDH with onset in children and adolescents represent a matchless opportunity to understand mechanisms involved in adult CDH. The aim of this study was to evaluate the diagnosis, prognosis and psychiatric co-morbidity of CDH with young onset in the young. Fifty-nine CDH patients has been followed from 1997 to 2001 in our department. Headache and psychiatric diagnoses were made on the basis of the international system of classification (International Headache Society, 1988; DSM-IV). Chi2 test and multinomial logistic regressions were applied to analyse factors predicting outcome. The current diagnostic system allows a diagnosis in 80% of CDH patients, even if age-related characteristics have been evidenced. Psychiatric disorders are notable in CDH (about 64% of patients) and predict (mainly anxiety) a poorer outcome. Surprisingly, analgesic overuse is not involved in the chronicization process. Diagnosis of CDH needs further study. Psychiatric disorders predict a worse outcome and greater account should be taken of them in treatment planning.     

Chronic daily headache in children and adolescents: a clinic based study from India

Chronic Daily Headache (CDH) is uncommon in Indian children compared to their adult counterpart. This is a retrospective study looking at the headache phenomenology of CDH in Indian children and adolescents. The validity of the case definitions of subtypes of chronic primary headaches mentioned in the IHS 2004 classification have been evaluated. 22 children (age range 8-15 years; M : F-16 : 6) diagnosed as having primary CDH using a modified definition seen between 2002 and 2003 have been studied. CDH has been defined as daily or near daily headaches > 15d/month for > 6 weeks. The rationale for this modified definition has been discussed. Majority of children (15/22) had a more or loss specified time of onset of regular headache spells resembling New Daily Persistent Headache (NDPH) but did not fulfil totally the diagnostic criteria of NDPH as laid down by IHS 2004. In all cases headache phenomenology included a significant vascular component. Headache phenomenology closely resembled Chronic Tension Type Headache (CTTH) in 4 patients and Chronic Migraine in 3 patients. However, in no patient in these groups, a history of evolution from the episodic forms of the diseases could be elicited. Heightened level of anxiety mostly related to academic stress and achievement was noted in the majority (19/22). Only a minority of patients (3/22) had anxiety and depression related to interpersonal relationships in the family. Medication overuse was not implicated in any patient. CDH in children in India is very much different from CDH in adults with the vast majority of patients exhibiting overlapping features of migraine and tension-type headache. There is need for a modified diagnostic criteria and terminology for chronic primary headaches in children.     

Chronic daily bilateral headache responsive to indomethacin

Indomethacin is known to be specifically effective for chronic paroxysmal hemicrania, episodic paroxysmal hemicrania, and hemicrania continua. Different forms of idiopathic stabbing headaches have also been responsive to indomethacin, but less consistently than the others. Two cases of indomethacin-responsive headache are reported. One patient presented with what appeared to be new-onset, chronic, daily, bilateral headache aggravated by coughing. Both the chronic daily headache and the exacerbations induced by coughing were suppressed with indomethacin therapy. The second patient experienced hemicrania continua responsive to indomethacin, and the response persisted even when the headache evolved into bilateral continuous pain. There may be other idiopathic primary headache disorders that are peculiarly responsive to indomethacin. When any primary headache disorder does not respond to standard therapy, a brief therapeutic trial of indomethacin is warranted.     

Chronic frequent headache in the general population: comorbidity and quality of life

We studied the nature and extent of comorbidity of chronic frequent headache (CFH) in the general population and the influence of CFH and comorbidity on quality of life. Subjects with CFH (headache on >14 days/month) were identified in a general health survey. We sent a second questionnaire including questions on comorbidity and quality of life to subjects with CFH and subjects with infrequent headache (IH) (1-4 days/month). We recoded comorbidity by using the Cumulative Illness Rating Scale (CIRS) and measured quality of life with the RAND-36, a Dutch version of Short Form-36. CFH subjects (n = 176) had higher comorbidity scores than the IH subjects (n = 141). Mean CIRS scores were 2.94 for CFH and 1.55 for IH [mean difference 1.40, 95% confidence interval (CI) 0.91, 1.89]. The mean number of categories selected was 1.92 in CFH and 1.10 in IH (mean difference 0.82, 95% CI 0.54, 1.11). Fifty percent of CFH subjects had a comorbidity severity level of at least 2, indicating disorders requiring daily medication, compared with 28% of IH subjects (mean difference 22%, 95% CI 12, 33). CFH subjects had more musculoskeletal, gastrointestinal, psychiatric and endocrine/breast pathology than IH subjects. Quality of life in CFH subjects was lower than that of IH subjects in all domains of the RAND-36. Both headache frequency and CIRS score had a negative influence on all domains. We conclude that patients with CFH have more comorbid disorders than patients with infrequent headaches. Many CFH patients have a comorbid chronic condition requiring daily medication. Both high headache frequency and comorbidity contribute to the low quality of life in these patients.     

Disability in chronic migraine with medication overuse: treatment effects at 3 years

OBJECTIVES: To determine the clinical status, with respect to pain indices and disability level, of chronic migraine patients with medication overuse who were treated 3 years previously. BACKGROUND: Patients who have chronic migraine accompanied by medication overuse are particularly difficult to treat. Investigations are limited in number, few have included follow-up beyond 6 months, and almost none have examined whether treatment leads to concurrent improvements in disability and functional impairment. In a prior report, we described the clinical course of 84 such patients followed for 1 full year after treatment. METHODS: These same 84 patients were followed for 2 additional years to assess longer term maintenance of effects, using measurement procedures identical to those in the original investigation. RESULTS: Both endpoint and completer analyses revealed significant improvement on all measures studied-headache days per month, analgesic consumption, and MIDAS scores (Total, Headache Frequency, and Headache Intensity)-with some loss of benefits over time for the pain indices. MIDAS total scores, however, were lower at 36 months than at 6 months. Comparisons of those who completed the 3-year follow-up to those who did not revealed few differences at baseline. All of this suggests attrition did not have a bearing on outcome. DISCUSSION: High levels of maintenance were revealed at 3 years. Even though reports of pain revealed some lessening of effects, this was not accompanied by reports of deterioration in functioning. This suggests that patients have learned to adapt and adjust to headaches in their daily lives.     

Psychiatric comorbidity in the evolution from migraine to medication overuse headache

We set out to study the role of psychiatric comorbidity in the evolution of migraine to medication overuse headache (MOH) by a comparative study of 41 migraineurs (MIG) and 41 patients suffering from MOH deriving from migraine. There was an excess risk of suffering from mood disorders [odds ratio (OR) = 4.5, 95% confidence interval (CI) 1.5, 13.5], anxiety (OR = 5, 95% CI 1.2, 10.7) and disorders associated with the use of psychoactive substances other than analgesics (OR = 7.6, 95% CI 2.2, 26.0) in MOH compared with MIG. Retrospective study of the order of occurrence of disorders showed that in the MOH group, psychiatric disorders occurred significantly more often before the transformation from migraine into MOH than after. There was no crossed-family transmission between MOH and psychiatric disorders, except for substance-related disorders. MOH patients have a greater risk of suffering from anxiety and depression, and these disorders may be a risk factor for the evolution of migraine into MOH. Moreover, MOH patients have a greater risk of suffering from substance-related disorders than MIG sufferers. This could be due to the fact that MOH is part of the spectrum of addictive disorders.