Playing the lottery or slot machines in casinos – most of us have gambled in our lives. While this is usually an enjoyable activity, it becomes a problem for 1-3% of the population. Patients with gambling disorder can lose large amounts of money, jeopardize their careers or relationships, and struggle to control their gambling. To date, we know very little about the underlying neurobiology of gambling disorder.
A study led by Dr Samuel Chamberlain from the Department of Psychiatry has investigated the brain structure of patients with gambling disorder. Specifically, the team was interested in white matter tracts – the tissue containing axons surrounded by protective myelin sheaths. White matter enables the communication between different areas of the brain by connecting grey matter structures – the tissue containing the cell bodies of neurons.
Sixteen patients with gambling disorder who had failed previous treatments and fifteen healthy controls participated in the experiment. They underwent magnetic resonance imaging while resting in the scanner. The structure of their white matter was analysed by measuring fractional anisotropy. This measure describes the flow of water. In a myelinated axon, water mostly flows along one axis; the myelin barrier prevents it from diffusing in other directions. This restricted flow would be represented by a high fractional anisotropy. In contrast, a very low value reflects an equal diffusion of water in all directions. Without restriction, water can flow relatively freely in any direction.
Patients with gambling disorder had reduced fractional anisotropy in the corpus callosum – the bundle of fibres connecting the two halves of our brains. These tracts are important to connect areas in opposite parts of the brain and to integrate information. Previous studies have suggested that the corpus callosum is involved in inhibitory control. The low fractional anisotropy in patients with gambling disorder suggests that these important tracts are damaged or more disorganised, possibly explaining patients’ difficulty in controlling their gambling.
It is unclear whether this abnormality is a cause or consequence of gambling disorder: a disorganised corpus callosum might make you more vulnerable to developing a gambling disorder, or it might be the result of gambling compulsively for a long time.
We spoke to Dr Chamberlain about why the abnormalities in the corpus callosum are important:
“This brain region plays a key role in our ability to suppress impulsive and compulsive behaviors. The results are important because they suggest that gambling disorder shares some similarities with substance use disorder, and obsessive-compulsive disorder, in terms of neurobiology. This has implications for how we conceptualise these mental health disorders, but also how we treat them.”
Professor Jon Grant, senior author of the study, added that these results might help with the early detection of gambling disorder:
“The findings of disorganized white matter tracts in the corpus callosum could represent a vulnerability marker in gambling disorder. If this holds true, then it opens up the possibility of using imaging for early identification of people with possible gambling problems. Early interventions will likely be much more successful than trying to treat people who are at this stage of severity.”
Written by Julia Gottwald