Migraine is known to represent one of the most disabling neurological disorders1. In most cases, attacks recur episodically (episodic migraine, EM), however in a small, but relevant portion of patients, migraine acquires a chronic pattern (chronic migraine, CM) with at least 15 monthly headache days for at least 3 months, often associated with overuse of acute medications (MO)2. Current evidence suggests that, besides socio-demographic/lifestyle habits and medical history factors3, also psychological aspects may play a relevant role in the transformation of EM into CM, in particular in case of MO. CM/CM + MO is indeed strongly associated with psychopathologies, including dependence, anxiety, and depression, and personality disorders4–10, along with childhood trauma, life events, and alexithymia11–13. Importantly, comorbid psychopatologies bear a negative prognostic value in the outcome of migraine and in its response to treatments4,14–16. In addition to the well-known overlap between psychopathological comorbidities and CM + MO, scientific research interest is directed toward identifying all factors related to this complex clinical condition. According to the biopsychosocial model, there is a complex interrelationship between biological, psychological, and psychosocial vulnerabilities that mutually influence each other17. In other words, diversity in the expression of migraine, including severity, duration, and impact, results not only from the patient's biological characteristics, but also from the interaction with psychological state and social context, which can shape perceptions and response to the disease18.
Regarding social context, evidence suggests that migraine is a burdensome disease associated to many psychosocial difficulties – including social functioning19. Recent studies have investigated in this clinical population those social cognitive abilities that underline social interactions, that is the mental operations that allow one to decipher information about the intentions and affective states of social interlocutors20. Among these social cognitive skills, Theory of Mind (ToM), the ability to infer one's own and others' mental states, such as desires, emotions, and beliefs21, is fundamental to guide social interactions because people’s mental states determine their actions22. As far as we know, ToM is a component of social cognition of concern in CM/CM + MO, as recent research in this area has shown mentalization deficits in this population. For instance, Bouteloup23 comparing patients with severe EM and CM with healthy controls (HC), found difficulties in social and emotional cognition in the clinical populations. Raimo24 explored the neuropsychological correlates of ToM and found that CM patients had difficulties in the cognitive dimension involved in inferring the mental states of others. Romozzi25 compared CM + MO, EM, and HC with regard to recognition of complex emotions, knowledge of one's own and others' mental states, and levels of alexithymia, finding impairment in all dimensions in CM + MO. Bottiroli et al. 26 have recently compared CM + MO patients to EM and HC in many aspects of social cognition, including abilities, beliefs, traits, and social relationships. What they found was that the two migraine groups performed similarly – and worse than HC – in terms of socio-cognitive abilities, but the CM + MO was more impaired in the affective dimension of ToM.
Two main considerations could be drawn from these investigations. Firstly, most ToM studies in this field have been conducted using static scenario-based tasks, such as stories grounded in false belief or faux pas understanding23,24,26. One or more characters are presented with limited contextual information and participants must infer the mental states of the character presented. Photographs of the ocular region of the face were also used23–26. Although these tasks were very useful in understanding ToM functioning, they often fail to truly test the ability to mentalize in a manner similar to what happens daily in real life. More specifically, these tasks lack ecological validity in that they require participants to use their ToM skills in static situations that are oversimplified, often unimodal (verbal or visual), based on few indicators or cues, and finally very different from real-life situations. Secondly, typical ToM tasks are able to capture only the presence or absence of mentalizing evaluating right or wrong answers. However, beyond a complete lack of ToM, there are multiple ways in which mentalizing can go awry. Hence, other categories of mentalizing should be considered: less ToM (hypo-mentalizing) and excessive ToM (hyper-mentalizing). The relevance of this differentiation is supported by different patterns of difficulties emerged in different clinical conditions27–31. For instance, autistic-spectrum and psychotic-spectrum conditions such as schizophrenia represent two diametrically opposite phenotypes of disorders of social cognition, which is underdeveloped in autistic-spectrum conditions and hyper-developed on the psychotic spectrum32. In particular, autism-spectrum disorder is characterized by poor ToM performance and impairments in the reasoning of intentions and emotions that highlight social conventions33. By contrast, ToM deficits increase in severity along the psychotic spectrum, with schizophrenia exhibiting impaired, inflexible, or extreme inferences regarding social cues and over-attribution of mental states and intentions34.
With all these assumptions in mind, the present study aimed to evaluate ToM in CM + MO compared to EM using the Movie for the Assessment of Social Cognition (MASC35), a task consisting of the presentation of a 15-minute video clip of social interactions close to real life encounters in which participants are asked to identify and attribute mental states online. The reason for choosing to use this task is threefold. First, it allows an ecologically valid assessment of social interactions in everyday life, as it is a dynamic task that combines verbal and visual content. Second, this ecological task assesses two different aspects of ToM, namely affective ToM and cognitive ToM, assuring a more complete assessment. Cognitive ToM involves the representation of thoughts, intentions or beliefs, whereas affective ToM the representation of feelings36,37. Third, in addition to accuracy scores, the MASC allows to examine the type of errors made in the misattribution of mental states to others, distinguishing between hypo-mentalization (under-attribution of intentions to others) and hyper-mentalization (over-attribution of intentions to others). According to our previous findings26, our hypothesis is that CM + MO patients are characterized by a marked impairment in the affective component of the MASC, that differentiate them from EM. This hypothesis is also supported by previous evidence showing that affective ToM versus cognitive ToM may be particularly impaired in unipolar depression38,39, a condition that is particularly recurrent in CM + MO40. As error types, since no previous studies have been conducted on CM + MO, it is difficult to draw definitive hypothesis in the field of this clinical population. However, if we consider that patients with CM/CM + MO are typically characterized by alexithymia and difficulties in terms of emotional awareness11–13, it could be hypothesized that they are more prone to make errors characterized by reduced mental state attributions, i.e., hypo-mentalization. Similarly, patients with depression assessed with this same task were also found to be characterized by a tendency to hypo-mentalization38. Because this is the first study using MASC in CM + MO, we also administered a classic ToM task, widely used in previous research in this population23–26, the Reading the Mind in the Eyes (RMET41).