Why Do Migraines Often Decrease As We Age?

Brain Energy Deficit as a Source of Oxidative Stress in Migraine: A Molecular Basis for Migraine Susceptibility

People with migraine are prone to a brain energy deficit between attacks, through increased energy demand (hyperexcitable brain) or decreased supply (mitochondrial impairment). However, it is uncertain how this precipitates an acute attack. Here, the central role of oxidative stress is adduced. Specifically, neurons' antioxidant defenses rest ultimately on internally generated NADPH (reduced nicotinamide adenine dinucleotide phosphate), whose levels are tightly coupled to energy production. Mitochondrial NADPH is produced primarily by enzymes involved in energy generation, including isocitrate dehydrogenase of the Krebs (tricarboxylic acid) cycle; and an enzyme, nicotinamide nucleotide transhydrogenase (NNT), that depends on the Krebs cycle and oxidative phosphorylation to function, and that works in reverse, consuming antioxidants, when energy generation fails. In migraine aura, cortical spreading depression (CSD) causes an initial severe drop in level of NADH (reduced nicotinamide adenine dinucleotide), causing NNT to impair antioxidant defense. This is followed by functional hypoxia and a rebound in NADH, in which the electron transport chain overproduces oxidants. In migraine without aura, a similar biphasic fluctuation in NADH very likely generates oxidants in cortical regions farthest from capillaries and penetrating arterioles. Thus, the perturbations in brain energy demand and/or production seen in migraine are likely sufficient to cause oxidative stress, triggering an attack through oxidant-sensing nociceptive ion channels. Implications are discussed for the development of new classes of migraine preventives, for the current use of C57BL/6J mice (which lack NNT) in preclinical studies of migraine, for how a microembolism initiates CSD, and for how CSD can trigger a migraine.

Migraine in mitochondrial disorders: Prevalence and characteristics

Background Migraine is a well-known feature of mitochondrial disorders (MDs). However, no systematic epidemiological data are available in large populations of patients. Aims The aim of this cross-sectional cohort study was to describe the prevalence and migraine characteristics in a large cohort of patients with mitochondrial encephalomyopathies. Methods We studied 93 consecutive patients with characterised MDs referred to our Neuromuscular Unit during a 12-month period. All patients (age range = 16-78 years; 31 men; 58 progressive external ophthalmoplegia [PEO], 12 myoclonic epilepsy with ragged red fibres [MERRF], eight mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes [MELAS], two mitochondrial neurogastrointestinal encephalomyopathy [MNGIE] and 13 other MDs) underwent a structured diagnostic headache interview using an operational diagnostic tool following the IHS criteria. If they met the criteria for migraine, they were included in the 'Migraine Group'. The other patients were counted in the 'No Migraine Group'. Patient demographic and migraine characteristics were examined. Clinical, neuroradiological and neurophysiological data were compared between groups. Results Migraine was reported in 35.5% of patients. Migraine without aura was the most common headache (81.8%). The migraine group showed younger age ( P < 0.01), increased prevalence of epilepsy ( P = 0.01), myoclonus ( P = 0.03), stroke-like episodes ( P = 0.03) and decreased prevalence of muscle weakness ( P < 0.01). Multivariate analysis showed that migraine was positively associated with absence of muscle weakness ( P = 0.04) and presence of EEG abnormalities ( P = 0.02). Conclusion Migraine has a higher prevalence in MDs compared with general population-based data, independently from genotype or phenotype. Migraine is not merely a phenotypic aspect of specific MDs but is rather the expression of vulnerability of the central nervous system, probably directly related with defects of the respiratory chain.

Migraine Triggers and Oxidative Stress: A Narrative Review and Synthesis

BACKGROUND

Blau theorized that migraine triggers are exposures that in higher amounts would damage the brain. The recent discovery that the TRPA1 ion channel transduces oxidative stress and triggers neurogenic inflammation suggests that oxidative stress may be the common denominator underlying migraine triggers.

OBJECTIVE

The aim of this review is to present and discuss the available literature on the capacity of common migraine triggers to generate oxidative stress in the brain.

METHODS

A Medline search was conducted crossing the terms "oxidative stress" and "brain" with "alcohol," "dehydration," "water deprivation," "monosodium glutamate," "aspartame," "tyramine," "phenylethylamine," "dietary nitrates," "nitrosamines," "noise," "weather," "air pollutants," "hypoglycemia," "hypoxia," "infection," "estrogen," "circadian," "sleep deprivation," "information processing," "psychosocial stress," or "nitroglycerin and tolerance." "Flavonoids" was crossed with "prooxidant." The reference lists of the resulting articles were examined for further relevant studies. The focus was on empirical studies, in vitro and of animals, of individual triggers, indicating whether and/or by what mechanism they can generate oxidative stress.

RESULTS

In all cases except pericranial pain, common migraine triggers are capable of generating oxidative stress. Depending on the trigger, mechanisms include a high rate of energy production by the mitochondria, toxicity or altered membrane properties of the mitochondria, calcium overload and excitotoxicity, neuroinflammation and activation of microglia, and activation of neuronal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. For some triggers, oxidants also arise as a byproduct of monoamine oxidase or cytochrome P450 processing, or from uncoupling of nitric oxide synthase.

CONCLUSIONS

Oxidative stress is a plausible unifying principle behind the types of migraine triggers encountered in clinical practice. The possible implications for prevention and for understanding the nature of the migraine attack are discussed.