When William Harvey described cardiac circulation, he had no knowledge of how capillaries connect arteries to veins. Yet, building on what he could observe, he proposed a working theory. Trouble in Mind is an attempt to explore how a modern-day Harvey would make sense of psychiatric illness. Its author, Professor Dean MacKinnon, writes that, unlike Harvey, modern-day psychiatry hesitates to build a theory that considers any mechanisms that cannot yet be demonstrated scientifically. As a result, it lacks a model which describes mental dysfunction as arising directly from brain function and which integrates psychiatric, neurobiological and psychological understanding. MacKinnon aims to address this shortfall and provide a functional model of the mind which can be used to explain psychiatric problems.

Starting from first principles, the book begins by describing the mind’s most basic functioning. This includes the processing of sensory information. Hallucinations and catatonia arise at this level as malfunctions of processing input (perception), or output (motor activity) respectively. Sensory information leads to arousal and appetites, and psychiatric disorder can be explained at this level too. For example, delirium can be thought of as a confused state fuelled by abnormal arousal. Further complexity in brain function leads to habits, motives, biases and temperament and these explain in turn more complex psychiatric disorders. For instance, when there is a disconnect between our internal state of arousal and our actual perceptions, our beliefs can become delusional.

Trouble in Mind is rich with ideas and I think that it will become a classic of non-mainstream psychiatric thinking. It clearly and confidently relates its propositions and MacKinnon has a novel approach which makes intuitive sense. My only reservation concerns the concluding chapter where the treatment of mental illness using the ideas developed in the preceding chapters is addressed. It is disappointingly brief and as a result I felt left without adequate guidance as to how I might integrate MacKinnon’s thinking into my everyday practice and research.