worried face
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Nearly 600 genes associated with neuroticism have been identified in the biggest study of its kind so far. The research shows that neuroticism has two different subtypes which are coded by different sets of genes, and is a big step in our understanding of the underlying biology of personality.

The research, led by Danielle Posthuma of Vrije Universiteit Amsterdam, looked at the genomes and personality questionnaires of nearly half a million people from several countries.

Neuroticism is one of the "big five" personality traits. We already knew that people who score highly for neuroticism - an important risk factor for schizophrenia and depression - are more likely to worry and be moody, anxious and guilty.

The team found around 600 genes that were involved in neuroticism, and that the personality trait seemed to be made up from two different clusters of genes. Each cluster appears to contribute to a separate subtype of neurotic behaviour.

These were dubbed 'depressed affect' - the tendency to experience frequent mood changes and feel lonely, and 'worry' - a tendency to be anxious and fret about what other people think of you. Full-blown neuroticism seemed to arise from a mix of the genetic signals from both clusters.

Genetic risk

The research provides important leads for future study into the neurobiology of personality. But it doesn't mean you could determine a person's personality from their DNA, says Posthuma, as hundreds of genes each have a small effect. "Currently we can't make reliable predictions for the individual." We can only say that people with a particular genetic profile have, for example, a 10 per cent increased risk being neurotic, she adds.

Other factors, such as our experiences and the environment in which we grow up, will also play a role in our personalities - and research show they can change over time.

A separate analysis also lead by Posthuma looked into the genetics of intelligence. It identified 190 new genes associated with intelligence, and found a protective effect of high IQ against Alzheimer's disease and Attention deficit hyperactivity disorder (ADHD).

Such large-scale projects have only been possible recently, thanks to the plummeting cost of DNA sequencing and the availability of massive genetic databases.

Journal reference: Nature Genetics, DOI: doi.org/10.1038/s41588-018-0151-7