A New Pathway Between Body and Mind?

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One of the core implications of psychology and psychiatry of recent decades is a simple anti-Cartesian lesson: The mind and the body are endlessly intertwined with each other. This has led to intriguing diagnostic proposals; to take one example, the idea that inflammation is a possible cause of depression. And it has inspired undoubtedly useful and surprising interventions, such as the integration of yoga and forms of bodywork into traditional "talk therapy." Even now, the realm of connections between body and mind leaves much to be explored. One in particular warrants attention: the observation that a class of conditions, known as hereditary connective tissue disorders, can have widespread and often surprising consequences for the mind.

What are hereditary connective tissue disorders (HDCTs)? These are disorders that a person inherits genetically (hence the name) that affect the body's connective tissues, the abundant tissues that hold together and support a person's body, including bones, cartilage, and ligaments. There are several such disorders, with Marfan syndrome and Ehlers-Danlos syndrome (EDS) being two of the best known. Given the widespread role of connective tissue, the implications of these conditions can be far-reaching and often serious. Marfan syndrome, for instance, is associated with potentially fatal cardiac complications (though these are now treatable through medication and surgery). But connective tissue disorders may have psychological implications as well.

The best-studied of these are perhaps those associated with EDS. Individuals with EDS characteristically experience fatigue and pain which, if their EDS is unrecognized, can seem inexplicable. Accordingly, these patients can be given psychological diagnoses, such as functional neurological disorder, when their symptoms are in fact non-psychological in their origins. But the associations between EDS and psychology are still more far-reaching than this. Studies suggest that individuals with EDS have significantly higher rates of ADHD, autism spectrum disorders, and anxiety disorders compared to the general population. The mechanisms that explain these connections remain imperfectly understood and the object of ongoing research.

Antoni Bulbena and his colleagues were among the first to identify correlations between EDS and anxiety, and they have proposed that there is a "neuroconnective phenotype" — a model for representing the connections between the psychological manifestations of EDS (such as anxiety) and the non-psychiatric manifestations (such as having extremely flexible joints, or joint hypermobility). Part of what is crucial in this picture is that we are not merely describing correlations between psychological conditions and connective tissue disorders, but understanding EDS as a fundamentally physical condition that nonetheless shows up, for some patients, in mental or psychiatric ways. This suggests, as Bulbena and others have argued, a new approach to treating certain patients, one in which the boundary between mind and body is a permeable one.

This may be only the beginning of understanding the psychology of HDCTs. Consider Marfan syndrome, a hereditary connective tissue disorder that is estimated to affect about 1 in 5,000 people (so in the neighborhood of 60,000 to 70,000 people in the United States alone). People with Marfan syndrome, like people with EDS, often experience pain and fatigue as a result of their condition. But, as with EDS, the connections with psychology appear to go well beyond this. For example, there appears to be a correlation between Marfan syndrome and schizophrenia, which some suggest could be due to a connection between the genes responsible for each of these conditions. But our understanding of these connections, such as they, remains highly conjectural and incomplete.

Even in our present state of knowledge, however, a couple of lessons stand out. One is the need for multidisciplinary care for patients with hereditary disorders of connective tissue. The various manifestations of these disorders have already made such clinics necessary, integrating for example cardiology with genetic counseling. The psychological aspects of these conditions suggest that these clinics may also need to integrate psychiatry, psychology, and social work, something that is already underway at a number of academic medical centers.

Another more broadly philosophical lesson is the following: It is true, if uninformative, to observe that the mind and the body are connected to each other. The brain, after all, is part of the body, and the mind is connected, somehow, to the brain. For all of that, there are strong disciplinary and institutional boundaries between the clinical treatment of the mind and the body. Reflection on hereditary connective tissue disorders indicates one limitation of this approach. Certain conditions affect both mind and body, in surprising ways, and in ways that cannot be factored neatly into a psychological and a physiological component. If new approaches to HDCTs are any indication, then we should expect future treatment of psychological symptoms to take an ever more embodied turn.