Are Mental Disorders Brain Disorders?

In today's post, Anneli Jefferson discusses her new book, Are Mental Disorders Brain Disorders? (Routledge 2022). She is a lecturer at Cardiff University who works in the philosophy of psychology, moral philosophy, and at the intersection of the two. 

In the last 20 years or so, neuroscience and psychiatry have increasingly been researching what brain differences can be found in people suffering from mental distress, and how these might help to explain and treat mental disorders. There is a long-standing belief that mental disorders must be brain disorders, because whatever psychological dysfunction we find must have some basis in the brain. However, many psychiatrists, clinical psychologists and philosophers strongly resist this idea, and debates about this issue can get quite heated. In my book I set out to get to the bottom of what makes this debate so intractable and provide a way forward in the debate.

I argue that resistance to calling mental disorders brain disorders stems primarily from a very narrow and specific view of what is entailed when we call a condition a brain disorder. This narrow view looks to paradigmatic brain disorders such as brain cancer as a model for what makes a condition a brain disorder. It concludes that a condition can only be a brain disorder if the following conditions are met: dysfunction in the brain is specifiable independently of the psychological level, it causally precedes mental symptoms, and treatment of the disorder targets the brain directly, for example through medication or surgery. (This specification that the brain is targeted directly is important because psychological treatment through talking therapy targets the brain as well, but does so indirectly.)

Anneli Jefferson

The narrow view is unsatisfactory because both the etiology of brain disorders and the treatment involve a plurality of factors (Kendler 2012). Furthermore, somatic dysfunction, too, is not specifiable independently of the adverse effects a structural or functional anomaly in the body has for an organism. It’s therefore unclear why we should demand a higher standard for brain dysfunction. 

Instead, we should say that differences in brain structure or function that we find in mental health conditions are dysfunctional precisely because they realize mental dysfunction. This gives us a more modest notion of brain dysfunction and disorder, which only requires that we find differences in the brain that are sufficient for realising psychological dysfunction. This means that for many psychiatric disorders, brain dysfunction will only be specifiable as such because it realises psychological dysfunction.

The second half of the book considers objections and implications, I address the objection that brain disorder labels are committed to a problematic reductionism and that mental disorders are relational (externalist) in a way that a focus on dysfunction in the brain cannot allow for.

Finally, I discuss worries about how brain disorders affect responsible agency and how the ‘brain disorder’ label might influence people’s self-perception and the way others see them. I argue that while brain disorders do often have an impact on responsible agency, we can and should only assess responsibility by looking at an agent’s psychological profile. Knowledge of brain dysfunction can inform such psychological assessments, but it cannot replace them. 

I then consider the worry that rightly or wrongly, hearing that a person is suffering from a condition that involves dysfunction in the brain will make people see them as unable to do anything to recover from or manage their condition and make them think that person is not responsible for their actions. I discuss two possible explanations for such effects: one is that we draw unwarranted conclusions by drawing analogies to certain paradigm brain disorders such as brain cancer, the other is the hypothesis that we are intuitive dualists, who think of brain and mind as separate. I end by proposing ways to mitigate these undesirable associations.