Why do some people have more control over their behaviour than others?
Sometimes our brains compel us to repeat choices that are
neither productive or rewarding - a subject of interest to
Professor Trevor Robbins at the University of Cambridge. For
example, he has shown that rats with a lower than usual number of
dopamine receptors in their brains are at risk for cocaine addiction.
Those rats self-administer cocaine to the exclusion of other
activities, and despite adverse consequences - two classic
criteria of addiction. His work suggests that humans with low
dopamine receptors may also be susceptible to addiction.
People with obsessive-compulsive disorder (OCD) - a notoriously
intractable disorder - similarly experience a difficulty in
stopping certain behaviours. fMRI and structural imaging studies
showed that the parts of the frontal cortex associated with
flexibility and inhibition control were under-activated in these
people, and they also had significantly decreased grey matter in
those areas compared with healthy controls.
An exciting result was that first-degree relatives of these
patients, although they did not have any behavioural symptoms of
OCD, showed the same inflexibility on the same tasks - and the
under-activations and decreased grey matter in the cortex. This
suggests OCD may be an endophenotype, a cognitive problem in the
genes of this family.
Professor Stephen Williams at the Institute of
Psychiatry (IoP) at King's College London and colleagues have
devised new methods that are making it possible to
diagnose psychiatric disorders such as autism, schizophrenia,
Alzheimer's ADHD and addiction with 85-90 per cent accuracy - and
to tell whether a patient is likely to respond to specific
Not only will this save patients months of
wasted time, misery and frustration as they wait to see if a
particular medication or treatment works for them - it also
removes stigma around psychiatric illness by objectifying it in a
Addiction, OCD, autism, schizophrenia and
impulsivity are all disorders that, untreated, have a very powerful
effect on our thoughts, choices and actions - and neuroscience is
showing us the roots of that effect in the sometimes overwhelmingly
compelling workings of the brain.
As is the case with our genes, it appears our
brains give us certain predispositions. Some of these are absolute
and inescapable. And some of them we can change - through our
choices, behaviours and sometimes through medical intervention, as
we shape ourselves over the course of our lives.