Book Review: The Imprinted Brain - How Genes Set the Balance Between Autism and Psychosis

The Imprinted Brain sets out a startling new theory that could reshape the way we think about the human brain. The central premise is of an evolutionary 'tug-of-war' taking place between genes inherited from your father and genes inherited from your mother. A 'win' for either the father's or the mother's genes could disrupt normal brain functioning, leading to disorders as seemingly disparate as autism and schizophrenia.

The theory is the brainchild of author Dr Christopher Badcock, a sociologist at London School of Economics, and Dr Bernard Crespi, a biologist at Simon Fraser University in Canada. They first published their idea in a series of articles in leading scientific journals, but this is the first book to give an account of their theory.

The book cleverly ties together evidence from genetics, evolutionary biology, psychology and psychiatry to introduce the 'imprinted brain theory'. Briefly, there are a set of genes which are expressed differently depending on whether they are inherited from the mother or the father, known as 'imprinted genes'. The theory holds that disruption to the typical expression of imprinted genes in the brain could result in an 'extreme paternal brain' or an 'extreme maternal brain', leading individuals to develop autism or schizophrenia respectively. This idea is delivered clearly and comprehensively, with reference to recent scientific literature as well as established theories of evolution and animal behaviour.

The imprinted brain theory is not entirely novel: the 'extreme male brain theory of autism' was proposed by Professor Simon Baron-Cohen over a decade ago. However, Badcock and Crespi introduce an important caveat, arguing that autism is not just an example of extreme maleness, but directly caused by the overexpression of paternal genes in the brain. To my knowledge, Badcock and Crespi are also the first to interpret schizophrenia as the direct opposite of autism; the consequence of an extreme maternal brain. The novelty of this theory meant that I began the book with some scepticism, but I found the logical, carefully constructed argument extremely compelling.

The book starts with a step-by-step description of autism and Asperger's syndrome, accompanied by engaging accounts and quotes from individuals with these disorders. These personal stories help to break up the text and enhance the reader's understanding of the disorders. Badcock also uses the same device to enliven the descriptions of schizophrenia. The introductory chapters also serve to draw the reader's attention to the opposing traits associated with autism and schizophrenia. One example is of the enhanced visual and spatial skills that are common among individuals with autism, but deficient among schizophrenia patients.

Some symptoms of autism and schizophrenia overlap, which seems to contradict the idea that the two disorders exist at opposite ends of the same spectrum. For example, both disorders are characterised by avoidance of social contact and misunderstanding of other's intentions. Badcock takes this in his stride and argues that, although symptoms can appear similar, they may have different underlying causes. This idea felt like a bit of a stretch initially, as if Badcock were twisting the facts to fit his theory. However, after he expanded on the idea and explored the potential mechanisms that underlie the overlapping symptoms, I became convinced.

The final chapter extends the theory to tackle the subject of genius. Badcock argues that genius, attributed to scholars such as Isaac Newton and John Nash, may arise when the extreme paternal brain and extreme maternal brain co-exist in the same person. He bases this theory on biographical literature, which suggests that Newton and Nash displayed both autistic and schizophrenic traits on different occasions. These historical characters may interest readers and they serve to illustrate an interesting point. However, I felt it could be unwise to make posthumous diagnoses based largely on biographical evidence.

I was left with the impression that genetic evidence to support the imprinted brain theory is currently lacking, so it will be interesting to see whether molecular genetics will bear out the theory in the laboratory. The idea is certainly intriguing and, if validated, could forever change the way we understand normal brain function, as well as two of the most common psychiatric disorders: autism and schizophrenia. This original and exciting theory, presented in an engaging and approachable style, makes the book well worth a read.

Buy The Imprinted Brain: How Genes Set the Balance Between Autism and Psychosis from Amazon UK.