Cognitive Dysfunction and Migraine
It will come as no surprise to any Migraineur reading this that Migraine attacks are frequently associated with cognitive and mental symptoms. Patients often find these symptoms to be some of the most significant contributors to Migraine attack-related disability.
Patients report experiencing issues with concentration, attention, planning, judgment, initiative, processing speed, language and memory. Unfortunately, the treatment medications available to Migraineurs typically do not relieve these symptoms.
However, despite the frequency with which patients report these symptoms, this does not necessarily mean Migraineurs are experiencing cognitive dysfunction during an attack. A research study presented at the 2013 International Headache Congress in June attempted to scientifically evaluate what patients so frequently deal with during their Migraine attacks.
Researchers have attempted to study this issue in the past, but these studies had significant limits. Most had small sample sizes, did not control for medication use, depression and other comorbid psychiatric conditions or aura. None controlled for something called the practice or learning effect bias that commonly results from repeated psychological testing. Five of seven existing published studies documented some cognitive dysfunction, such as speed of processing, attention and learning.
To avoid the limitations of past studies, the researchers needed a population of young patients with episodic Migraine, no diagnosis of Medication Overuse Headache and no psychiatric comorbidities who were willing to come in for testing during an untreated Migraine attack. As you might expect, it took a long time to recruit patients that met these criteria.
Patients were evaluated by a trained neuropsychologist twice: When not experiencing a Migraine attack and during an active, untreated Migraine attack. To avoid the practice/learning bias half had their first evaluation during an attack-free period and the other half had their first evaluation during an attack. It took almost six years for the researchers to get the patients who were tested during a non-attack period through the second evaluation since it had to be conducted during an untreated Migraine attack.
The patients in the two groups were very similar demographically (age, education, quality of life, headache impact test (HIT), etc.). On average when evaluated during an attack, the patients were eighth hours into the Migraine attack and rated the attack as moderate. Finally, while a few patients were on preventive medications, only one patient was taking topiramate. A common side effect of topiramate is cognitive issues.
The data supports the idea that cognitive function globally diminishes during a Migraine attack in patients with Migraine without aura. These researchers believe this is probably due to the Migraine attack itself.
On every measure taken by the researchers, patient scores were on average lower during a Migraine attack. This includes language, memory, learning and executive functions. But the data failed to achieve statistical significance except on one test (the California Verbal Language Test).
The patients experienced more anxiety when they were evaluated during an attack than when evaluated during a non attack period. The researchers do not believe this explains the observed differences in cognitive functioning.
Some brain functions are impacted more than others. The executive and learning functions of patients changed the most during a Migraine attack in this study. Executive functions are what allows us to use our past experiences to make decisions about present actions.
It is possible these findings represent reversible changes that accompany the attack in patients living with Migraine without Aura and do not continue to burden the patient long term. However, functional imaging and neurophysiological studies support the existence of brain changes in patients with Migraine without Aura. We don't yet know if there is a long term impact associated with the cognitive changes observed.
But another unanswered question is whether these cognitive issues are specific to Migraine. Could they be present in other Headache Disorders or in other conditions associated with pain?
Unfortunately, there are no equivalent studies on other conditions associated with acute pain to help determine if these results are specific to Migraine. But the researchers are working to recruit a control group of post-operative orthopedic patients with acute pain to learn more.
Raquel Gil-Gouvela. "Cognitive Dysfunction During a Migraine Attack - Study on Migraine without Aura." International Headache Congress. June 2013.
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