Overview
In this study, we aimed to determine whether a history of headache and migraine treatment affected baseline ImPACT composite scores. Our results suggest that individuals with this profile demonstrate higher symptom burden, lower visual memory, and higher visual motor scores at baseline. From the results of the current study, the effect of headache and migraine treatment on visual memory was detrimental, while the effect on visual motor speed appeared beneficial. Both findings were independent of the observed increased symptom burden. In contrast, verbal memory, reaction time, and impulse control scores did not significantly differ. Given the dearth of studies on baseline performance in adolescents with preexisting headache history, our results shed much-needed light on neurocognitive characteristics of this previously understudied patient population, providing a foundation for deeper examination of the effects of HA on neurocognitive functioning before and after head injuries.
mPCSS (Symptom burden)
The HA group had greater symptom burden, with increased mPCSS composite scores. Our finding suggests that caution should be taken when making a decision about diagnosis or treatment based on the changes in ImPACT values that can be suppressed or enhanced while under HA treatments, potentially helping to reveal whether symptoms seen after a concussion are due to the injury itself or preexisting pathologies such as headache [20]. This specific data point is therefore highly clinically valuable because it may prevent clinicians from mistakenly ascribing certain symptoms to concussions [21]. Although relatively little has been published on baseline performance in this specific patient population, a few other studies have reported similar results. For instance, Mannix et al. found that adolescent athletes with a history of medical treatment for headaches reported more baseline symptoms [22]. In fact, in the multivariate model from this same study, headache/migraine history was one of the most common factors related to baseline preseason symptom reporting, second only to mental health history.
Cottle et al. likewise reported that previous treatment for headaches and migraines correlated with increased total symptom score at baseline, as measured in National Collegiate Athletic Association (NCAA) Division I collegiate student-athletes via ImPACT [23]. Register-Mihalik et al. also discovered a similar association between preseason headaches and baseline symptom score/severity in their cohort of high-school and collegiate athletes [6]. Finally, Solomon et al. detected a significant difference between average total symptom scores on ImPACT in headache-treated and non-treated groups of National Football League (NFL) players, with those in the former reporting more symptoms on average [24]. Thus, our observation aligns with those from prior investigations into baseline symptomatology in this patient demographic.
Visual memory
Visual memory scores were also lower in the HA group. Once again, it is difficult to place this observation in context with previously reported findings because so few studies have been conducted on baseline performance in this subgroup. In the same study by Cottle et al., individuals previously treated for headaches had decreased visual memory scores on ImPACT testing; however, these differences were not ultimately statistically significant (71.0 vs. 76.0, dbaseline = -5.0, p =.048) [23]. In another study by Mihalik et al., visual memory scores in HA and non-HA groups did not significantly differ (75.69 vs. 74.74, dbaseline = 0.95) [25]. Terry et al. likewise found no difference in baseline performance for children with premorbid migraines compared to controls, including visual memory scores (70.59 vs. 71.19, dbaseline = -0.04) [10]. It should be noted that given the extremely low effect sizes of the differences in Visual Memory scores in the present study, these results may actually be consistent with prior works. Still, additional research is warranted to confirm whether HA individuals perform worse in visual memory or comparably to their non-HA counterparts. Notably, visual memory scores were consistently lower in the HA group even when subdivided into categories based on prior concussion history. Individuals with HA performed worse on this section regardless of whether they had sustained no, one, two, or three concussions. This finding suggests that decreased visual memory may be the common variable associated with HA. In other words, poorer performance on visual memory tasks as measured via ImPACT appears to be more significantly related to headache etiology than to the concussion itself.
Visual motor speed
In contrast, visual motor speed scores were higher in the HA group, a surprising trend that has not been widely reported in the literature. In fact, Cottle et al. found that visual motor speed scores were lower in those treated for migraines (p=.015), which directly conflicts with our results [23]. Mihalik et al. observed a similar pattern, albeit statistically insignificant (p = .054), of reduced visual motor speed scores in HA individuals [25]. Terry et al. did not find any significant differences in visual motor speed scores between migraine and control groups (p = .06) [10]. Although the low effect size of our result could signal a lack of clinical relevance and thus be consistent with prior reports, one other potential explanation for our disparate finding is that stimulant use was higher in our HA group. The use of stimulants, which was more prevalent in HA individuals, may have improved their visual motor speed performance on baseline ImPACT testing.
Although the use of stimulants has not been well studied in patients with a history of headaches, there has been some literature published on those with other clinical profiles, including ADHD [26]. Gardner et al. found that young athletes with ADHD and stimulant treatment had higher visual motor speed scores at baseline than those without any such treatment [27]. Even in healthy participants without any such disorders, stimulant use has been shown to improve visual processing speed, leading to increased visual motor speed scores on ImPACT testing [28]. Thus, there are emerging signs that stimulants may alter neurocognitive performance on ImPACT, at least in certain cohorts, which may be a confounder for our findings. Future studies will concentrate on HA individuals and will more closely examine the potential effects of stimulant use on baseline results in this patient population.
Verbal memory, reaction time, & impulse control
We did not detect any statistically significant differences in verbal memory scores, reaction time, or impulse control in our univariate or multivariable analyses, in line with findings from previous studies [23,24,25]. Hence, at least based on current evidence, HA individuals do not seem to perform differently than their non-HA counterparts in these areas on baseline ImPACT testing. That said, research on this patient population is still largely in this infancy, and so further exploration is needed to confirm that headache history does not have a meaningful influence on any of these three domains.
Migraine versus other headache types
This is the first study we are aware of that directly compared baseline performance between those who reported a history of migraine specifically versus those who report a history of unspecified headache. After controlling for appropriate covariates, we found no significant difference between the groups. This work requires future corroboration, but provides confidence that, despite differences in pathogenesis between migraine and other types of headaches, the primary analyses in this project were not unduly affected by combining subjects reporting prior treatment for migraine and those reporting prior treatment for non-specific headache.
Limitations
Our study involved a retrospective cross-sectional methodology, as have most other studies that have assessed different groups of adolescent athletes with baseline ImPACT testing. In order to attain a more comprehensive sense of baseline neurocognitive functions and how they might evolve, incorporating longitudinal schemes would be valuable. Very few have explored this avenue of investigation. However, one recent study evaluated the test-retest reliability of memory and speed of ImPACT over the course of two years across several different groups, including one with a history of treatment for headache/migraine [29]. These findings demonstrate the feasibility and utility of conducting baseline testing at multiple time points, especially in individuals with HA and other premorbid conditions. Future studies should strive to monitor baseline performance by building in more of these longitudinal designs. Additionally, prospective investigations should explore variations in different areas the HA group might have in the absence of ImPACT with new modalities such as eye tracking technology.
Utilizing other test batteries that more thoroughly assess neurocognitive and neuropsychological functions might also be worthwhile, helping to clarify whether HA results in deficits not visible on a short, computerized test such as ImPACT. Even though our findings increase confidence in evaluations of individuals with head injury, variations of responses are common, and other methods of assessment should be considered before making a diagnosis or treatment. Conducting additional studies, including ones that involve magnetic resonance imaging (MRI) or even functional magnetic resonance imaging (fMRI), would also help to correlate results observed here with specific imaging findings. fMRI has been used to probe the structural basis for conditions such as migraine, which is known to cause sensory hypersensitivities, pain, and other debilitating neurological complaints [30,31,32]. However, neither MRI nor fMRI has been used extensively in studies on adolescent athletes with this pathology or other types of headaches. These brain imaging modalities could help to uncover the anatomical and functional foundations for neurocognitive differences registered on tests such as ImPACT.
The higher prevalence of stimulant use in our HA group may have also skewed our data, leading to higher visual motor speed scores. Clarifying the role of stimulants with future work will help to address this concern. Additionally, for those subjects reporting non-migraine ‘headaches’, we do not know what type of headache they experienced. Other potential shortcomings of our study include the fact that we did not incorporate independent validity or effort indicators apart from those in ImPACT. We were also unable to validate certain self-reported information, including SSRI use and history of previous concussion. However, there is growing evidence that adolescent athletes report clinical details such as concussion history with a high degree of reliability, making this feature of our study slightly less objectionable [33]. Finally, we were not able to address the possibility that the certain subjects may have taken previous ImPACT tests prior to this study, which could have contributed to baseline differences observed.