We have formulated the first biotype taxonomy for depression and anxiety using high-definition MRI technology.
Biotypes are the distinct ways that brain circuits can get disrupted or stuck.
They accompany different types of symptom experiences and give us precision tools to help personalize treatment choices.
Re-imaging mental health as brain health
Mental disorders have not typically been considered “brain disorders.” Instead, “brain disorder” is normally used to refer to a neurological condition associated with a discrete lesion or degenerative process. This usage reflects our previously limited understanding of the real-time coordination of the brain – the brain in action.
Because of recent advances we can now peer inside the human brain in action in real-time and gain a precise understanding of mental disorders as disruptions in the functioning of the brain. Functional brain imaging technologies have advanced to the point where we can quantify how the brain is activating and connecting each second with high spatial resolution.
A major advance has been the Human Connectome Project which has mapped the human brain in a similar way to how the Human Genome Project mapped the human genes. Our Center is a major site for research that uses the Human Connectome Project's advanced imaging technologies to locate specific disconnections that define biotypes for depression and anxiety.
A coinciding major advance is the explosion of new machine-learning approaches for big data and the computational power to make them possible. The human brain is capable of 1 trillion connections – many more than there are stars in the Milky Way. This sophistication gives us our unique selves. As humans, we also share a reliance on some common sets of connections that form large-scale circuits. We might think of these large-scale circuits as ‘super highways’ for processing our thoughts and emotions. Such large-scale circuits govern emotional, cognitive, sensory, and self-reflective functions that define our sense of self and that, when disrupted, can account for the symptoms we experience in depression, anxiety, and related conditions. The universality of this circuit architecture has been demonstrated using a large-scale encompassing every major brain system at rest and during different task-evoked conditions.
What are biotypes?
Biotypes describe distinct types of circuit dysfunction that underlie different forms of depression and anxiety. The founding biotype taxonomy is based on six large-scale circuits implicated in these dysfunctions: the default mode, salience, negative affect, positive affect (reward), attention, and cognitive control circuits. Biotypes characterized by dysfunctions in these six circuits can cut across traditional diagnostic categories and may interact or co-occur for each person. In our ongoing research, we continue to refine the precision with which we quantify biotypes, and expand their application in other forms of disorder and in personalized tailoring of treatment selection.
We are inspired by transformations in other areas of medicine such as cancer and cardiovascular medicine. These advances have addressed similar challenges in translating complex biological signals into diagnostic subtypes of disorder and treatment applications. But, they are much further ahead in linking a taxonomy based on the organ of interest to subjective symptoms and treatment indications. For example, the EKG can be used to quantify types of arrhythmia due to electrical circuit dysfunctions (too fast, too slow, irregular) and to indicate specific treatments (pacemaker), and the angiogram to quantify types of blockage dysfunction due to coronary heart disease (clots, stroke, heart attack) and to indicate other treatments (lifestyle changes, medications, surgery).
Using biotypes to get the right treatment to the right person at the right time
Our breakthrough findings highlight the promise of using biotypes based on the organ of interest for mental health – the brain – to achieve more precise diagnoses and treatment indications. When we use brain circuit measures, we move the needle from the current chance level of getting the right treatment the first time to an accuracy that doubles the chances of getting it right.
To learn more, please find articles, videos, and additional resources on biotypes below: