Mitochondrial DNA in stroke and migraine with aura

The metabolic face of migraine - from pathophysiology to treatment

Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.

Pathophysiological targets for non-pharmacological treatment of migraine

Background Migraine is the most prevalent neurological disorder worldwide and ranked sixth among all diseases in years lived with disability. Overall preventive anti-migraine therapies have an effect in one patient out of two at the most, many of them being endowed with disabling adverse effects. No new disease-modifying drugs have come into clinical practice since the application to migraine of topiramate and botulinum toxin, the latter for its chronic form. There is thus clearly a need for more effective treatments that are devoid of, or have acceptable side effects. In recent years, scientific progress in migraine research has led to substantial changes in our understanding of the pathophysiology of migraine and paved the way for novel non-drug pathophysiological-targeted treatment strategies. Overview Several such non-drug therapies have been tested in migraine, such as oxidative phosphorylation enhancers, diets and non-invasive central or peripheral neurostimulation. All of them are promising for preventive migraine treatment and are quasi-devoid of side effects. Their advantage is that they can in theory be selected for individual patients according to their pathophysiological profile and they can (and probably should) be combined with the classical pharmacological armamentarium. Conclusion We will review here how knowledge of the functional anatomy and physiology of migraine mechanisms holds the key for more specific and effective non-pharmacological treatments.

Mitochondrial Dysfunction and Migraine

The molecular basis of migraine is still not completely understood. An impairment of mitochondrial oxidative metabolism might play a role in the pathophysiology of this disease, by influencing neuronal information processing. Biochemical assays of platelets and muscle biopsies performed in migraine sufferers have shown a decreased activity of the respiratory chain enzymes. Studies with phosphorus magnetic resonance spectroscopy (31P-MRS) have demonstrated an impairment of the brain oxidative energy metabolism both during and between migraine attacks. However, molecular genetic studies have not detected specific mitochondrial DNA (mtDNA) mutations in patients with migraine, although other studies suggest that particular genetic markers (i.e. neutral polymorphisms or secondary mtDNA mutations) might be present in some migraine sufferers. Further studies are still needed to clarify if migraine is associated with unidentified mutations on the mtDNA or on nuclear genes that code mitochondrial proteins. In this paper, we review morphological, biochemical, imaging and genetic studies which bear on the hypothesis that migraine may be related to mitochondrial dysfunction at least in some individuals.

Prevalence of migraine in persons with the 3243A>G mutation in mitochondrial DNA

BACKGROUND AND PURPOSE

Over the last three decades mitochondrial dysfunction has been postulated to be a potential mechanism in migraine pathogenesis. The lifetime prevalence of migraine in persons carrying the 3243A>G mutation in mitochondrial DNA was investigated.

METHODS

In this cross-sectional study, 57 mDNA 3243A>G mutation carriers between May 2012 and October 2014 were included. As a control group, a population-based cohort from our epidemiological studies on migraine in Danes was used. History of headache and migraine was obtained by telephone interview, based on a validated semi-structured questionnaire, performed by trained physicians.

RESULTS

The prevalence of migraine is significantly higher in persons carrying the 3243A>G mutation than in controls (58% vs. 18%; P < 0.001). This applies for both subforms of migraine, migraine without aura (47% vs. 12%; P < 0.001) and migraine with aura (18% vs. 6%; P < 0.001), and in females (58% vs. 24%; P < 0.001) and males (58% vs. 12%; P < 0.001) for any migraine.

CONCLUSIONS

A high prevalence of migraine in persons with the mDNA 3243A>G mutation was found. This finding suggests a clinical association between a monogenetically inherited disorder of mitochondrial dysfunction and susceptibility to migraine. Mitochondrial DNA aberrations may contribute to the pathogenesis of migraine.

No evidence of association between common European mitochondrial DNA variants in Alzheimer, Parkinson, and migraine in the Spanish population

Certain mitochondrial DNA (mtDNA) variants and haplogroups have been found to be associated with neurological disorders. Several studies have suggested that mtDNA variation could have an etiologic role in these disorders by affecting the ATP production on high-energy demanding organs, such as the brain. We have analyzed 15 mtDNA SNPs (mtSNPs) in five cohorts of cases presenting Alzheimer disease (AD), Parkinson disease (PD), and migraine, and in controls, to evaluate the role mtDNA variation in disease risk. Association tests were undertaken both for mtSNPs and mitochondrial haplogroups. No significant association was detected for any mtSNP or haplogroup in AD and PD cohorts. Two mtSNPs were associated with one migraine cohort after correcting for multiple tests, namely, T4216C and G13708A and haplogroup J (FDR q-value = 0.02; Santiago's cohort). However, this association was not confirmed in a second replication migraine series. A review of the literature reveals the existence of inconsistent findings and methodological shortcomings affecting a large proportion of mtDNA association studies on AD, PD, and migraine. A detailed inspection of the literature highlights the need for performing more rigorous methodological and statistical standards in mtDNA genetic association studies aimed to avoid false positive results of association between mtDNA variants and neurological diseases.

CoEnzyme Q10 and riboflavin: the mitochondrial connection

OBJECTIVE

We conducted a short review of relevant literature which contends that migraine is associated with a wide-spread metabolic abnormality of mitochondrial oxidative metabolism, leading to the use of riboflavin and coenzyme Q10 as prophylactic therapy for migraine.

BACKGROUND

Riboflavin and coenzyme Q10 supplementation has been recommended widely as safe and effective prophylactic therapy for migraine. The background neurophysiological studies that led to the development of this therapy, which are extremely complex, deserve wider distribution.

METHODS

A brief review of the relevant literature was conducted and summarized.

RESULTS

Brain energy metabolism in migraine has been found to be abnormal in all types of migraine, making the migrainous brain hyper-responsive to many stimuli. The metabolic abnormalities are more severe in the more-severe types of migraine, such as hemiplegic migraine and migrainous stroke, but they are present both during and between attacks. The metabolic abnormality in migraine extends beyond the brain to platelets and muscles, as proven by techniques of biochemistry, muscle morphology, and nuclear magnetic spectroscopy. There are strong similarities between migraine and certain inborn errors of metabolism, the metabolic encephalomyopathies, in which patients suffer genetic abnormalities in mitochondrial energy production to produce lactic acidosis, stroke, and migraine headaches. The theory of migraine as a mitochondrial disorder seems to have abundant evidence. However, aside from the genetic abnormalities discovered for the familial hemiplegic migraines, molecular genetic studies in migraine have been negative until recently, when whole genome sequencing has now reported positive results.

CONCLUSION

Arising from these extensive neurophysiological studies, the treatment of metabolic encephalomyopathies with pharmacological doses of riboflavin and coenzyme Q10 has shown positive benefits. The same treatment has now been applied to migraine, adding clinical support to the theory that migraine is a mitochondrial disorder.

Treatment of cyclic vomiting syndrome with co-enzyme Q10 and amitriptyline, a retrospective study

Background

Cyclic vomiting syndrome (CVS), which is defined by recurrent stereotypical episodes of nausea and vomiting, is a relatively-common disabling condition that is associated with migraine headache and mitochondrial dysfunction. Co-enzyme Q10 (Co-Q) is a nutritional supplement that has demonstrated efficacy in pediatric and adult migraine. It is increasingly used in CVS despite the complete lack of studies to demonstrate its value in treatment

Methods

Using an Internet-based survey filled out by subjects with CVS or their parents, the efficacy, tolerability and subject satisfaction in CVS prophylaxis were queried. Subjects taking Co-Q (22 subjects) were compared against those taking amitriptyline (162 subjects), which is the general standard-of-care.

Results

Subjects/parents reported similar levels of efficacy for a variety of episode parameters (frequency, duration, number of emesis, nausea severity). There was a 50% reduction in at least one of those four parameters in 72% of subjects treated with amitriptyline and 68% of subjects treated Co-Q. However, while no side effects were reported on Co-Q, 50% of subjects on amitriptyline reported side effects (P = 5 × 10^-7), resulting in 21% discontinuing treatment (P = 0.007). Subjects/parents considered the benefits to outweigh the risks of treatment in 47% of cases on amitriptyline and 77% of cases on Co-Q (P = 0.008).

Conclusion

Our data suggest that the natural food supplement Co-Q is potentially efficacious and tolerable in the treatment of CVS, and should be considered as an option in CVS prophylaxis. Our data would likely be helpful in the design of a double-blind clinical trial.

The primary headaches: genetics, epigenetics and a behavioural genetic model

The primary headaches, migraine with (MA) and without aura (MO) and cluster headache, all carry a substantial genetic liability. Familial hemiplegic migraine (FHM), an autosomal dominant mendelian disorder classified as a subtype of MA, is due to mutations in genes encoding neural channel subunits. MA/MO are considered multifactorial genetic disorders, and FHM has been proposed as a model for migraine aetiology. However, a review of the genetic studies suggests that the FHM genes are not involved in the typical migraines and that FHM should be considered as a syndromic migraine rather than a subtype of MA. Adopting the concept of syndromic migraine could be useful in understanding migraine pathogenesis. We hypothesise that epigenetic mechanisms play an important role in headache pathogenesis. A behavioural model is proposed, whereby the primary headaches are construed as behaviours, not symptoms, evolutionarily conserved for their adaptive value and engendered out of a genetic repertoire by a network of pattern generators present in the brain and signalling homeostatic imbalance. This behavioural model could be incorporated into migraine genetic research.

Mitochondrial DNA sequence analysis of patients with 'atypical psychosis'

Although classical psychopathological studies have shown the presence of an independent diagnostic category, 'atypical psychosis', most psychotic patients are currently classified into two major diagnostic categories, schizophrenia and bipolar disorder, by the Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) criteria. 'Atypical psychosis' is characterized by acute confusion without systematic delusion, emotional instability, and psychomotor excitement or stupor. Such clinical features resemble those seen in organic mental syndrome, and differential diagnosis is often difficult. Because patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) sometimes show organic mental disorder, 'atypical psychosis' may be caused by mutations of mitochondrial DNA (mtDNA) in some patients. In the present study whole mtDNA was sequenced for seven patients with various psychotic disorders, who could be categorized as 'atypical psychosis'. None of them had known mtDNA mutations pathogenic for mitochondrial encephalopathy. Two of seven patients belonged to a subhaplogroup F1b1a with low frequency. These results did not support the hypothesis that clinical presentation of some patients with 'atypical psychosis' is a reflection of subclinical mitochondrial encephalopathy. However, the subhaplogroup F1b1a may be a good target for association study of 'atypical psychosis'.

Mitochondrial DNA control region sequence variation in migraine headache and cyclic vomiting syndrome

Migraine headache is a very common condition affecting about 10% of the population that results in substantial morbidity and economic loss. The two most common variants are migraine with (MA) and without (MO) aura. Often considered to be a migraine-like variant, cyclic vomiting syndrome (CVS) is a predominately childhood condition characterized by severe, discrete episodes of nausea, vomiting, and lethargy. Disease-associated mitochondrial DNA (mtDNA) sequence variants are suggested in common migraine and CVS based upon a strong bias towards the maternal inheritance of disease, and several other factors. Temporal temperature gradient gel electrophoresis (TTGE) followed by cyclosequencing and RFLP was used to screen almost 90% of the mtDNA, including the control region (CR), for heteroplasmy in 62 children with CVS and neuromuscular disease (CVS+) and in 95 control subjects. One or two rare mtDNA-CR heteroplasmic sequence variants were found in six CVS+ and in zero control subjects (P = 0.003). These variants comprised 6 point and 2 length variants in hypervariable regions 1 and 2 (HV1 and HV2, both part of the mtDNA-CR), one half of which were clustered in the nt 16040-16188 segment of HV1 that includes the termination associated sequence (TAS), a functional location important in the regulation of mtDNA replication. Based upon our findings, sequencing and statistical analysis looking for homoplasmic nucleotide changes was performed in HV1 among 30 CVS+, 30 randomly-ascertained CVS (rCVS), 18 MA, 32 MO, and 35 control haplogroup H cases. Within the nt 16040-16188 segment, homoplasmic sequence variants were three-fold more common relative to control subjects in both CVS groups (P = 0.01 combined data) and in MO (P = 0.02), but not in MA (P = 0.5 vs. control subjects and 0.02 vs. MO). No group differences were noted in the remainder of HV1. We conclude that sequence variation in this small "peri-TAS" segment is associated with CVS and MO, but not MA. These variants likely constitute risk factors for disease development. Our findings are consistent with previous data demonstrating progression of CVS into MO in many cases, and the co-segregation in a maternal inheritance pattern of CVS and MO within families. A mitochondrial component in the pathogenesis of migraine and CVS has therapeutic implications, especially concerning the avoidance of fasting.

Headache and the risk of stroke

Several studies have suggested that migraine is a risk factor for stroke. The association between migraine and the risk of stroke has been observed most often among premenopausal women but also in some studies among men. The association may be stronger among women who smoke and among women using oral contraceptives compared with nonsmokers and nonusers. Classic migraine with aura may be a more powerful predictor of stroke than common migraine without aura. Findings of a recent population-based study suggest that subclinical brain lesions are more common among migraine patients, particularly among those with aura, than among the control subjects. Two cohort studies have shown that chronic non-specific headache also is related to increased stroke risk. The effect of treatment of migraine and other types of headache on the risk of stroke is not known. Even though the relative risk of stroke may be fairly high among migraine patients, the absolute risk is usually low due to low baseline risk among young people.

Study of Mitochondrial DNA Mutations in Patients With Migraine With Prolonged Aura

Ten patients with migraine with prolonged aura were studied for the presence of mitochondrial DNA point mutations utilizing DNA isolated from blood and hair samples. We analyzed for nine point mutations reported in patients with MELAS (A3243G, C3256T, T3271C, T3291C, A5814G, T8356C, T9957C, G13513A, and A13514G) and three secondary LHON mutations (T4216C, A4917G, and G13708A). None of the patients tested had any of these mutations in mitochondrial DNA. However, one patient was found to have a tRNA(Gln) A4336G mitochondrial DNA variant. From this study it appears that migraine with prolonged aura is not an oligosymptomatic form of MELAS and is not related to secondary LHON mutations. The significance of the tRNA A4336G variant is unknown.

Stroke in children: genetic and metabolic issues

The study of genetic and metabolic etiologies of pediatric stroke, both vascular and metabolic, allows an understanding of the causes of acute focal neurologic deficits in childhood. Here, the mendelian and mitochondrial genetic causes of pediatric stroke syndromes are reviewed. This approach elucidates the etiology of childhood stroke and illustrates many of the genetic risk factors that are found in adult-onset cerebrovascular disease. Therefore, the study of childhood stroke serves as a model to elucidate the potential risk factors for all stroke. Ultimately this will serve to develop a more rational preventive and therapeutic approach for all cerebrovascular disease.

Stroke treatment-specific considerations

Unusual causes of stroke account for a minority of all strokes, but they have specific diagnostic and therapeutic implications which must be considered early in the clinical course. This article focuses on arteriopathies such as arterial dissection, vasospasm-induced stroke, and vasculitis; hematological disorders such as hypercoagulable states, disseminated intravascular coagulation, and sickle cell disease; migraine-induced stroke, and cerebral venous thrombosis.

Molecular genetics of migraine headaches: a review

Following the recent discovery of neural calcium channel mutations in familial hemiplegic migraine, genetic linkage and association studies have been performed world-wide in an effort to unveil the genetic basis of the more common types of migraine too. Mutations in neural calcium channels, mitochondrial DNA, serotonin receptors and transporter, dopamine receptors and genetic prothrombotic risk factors have been especially investigated and are discussed here. No unambiguous conclusions have, however, been reached. FHM remains an isolated success story in the quest for the genetic basis of migraine.

Search for mitochondrial DNA mutations in migraine subgroups

It has been suggested that mitochondrial mutations cause migraine(-like) symptoms. The presence of mtDNA mutations (3243, 3271, 11084, and deletions) was investigated in three migraine subgroups (maternally transmitted migraine with and without aura, migrainous infarction, and nonfamilial hemiplegic migraine). No mutations were found. These mutations and deletions probably are not involved in the migraine subgroups studied, although an investigation of other material (e.g., muscle tissue) would have shown this with more certainty.