Low birth weight linked to psychosis-like symptoms

May 28 2009

Low birth weight babies are at greater risk of developing psychosis-like symptoms as they grow up, research suggests. The study, published in the June issue of the British Journal of Psychiatry, shows a link between children's size at birth and their mental health at the age of 12.

Researchers from the University of Bristol assessed 6,000 12-year-old children to find out if they had experienced any hallucinations or delusions over the last 6 months.

Of the 6,000 children, 820 (13%) had experienced at least one psychotic symptom. These included visual and auditory hallucinations, and delusions of being spied upon, persecuted or having their thoughts read.

All the children had been followed since birth as part of the Avon Longitudinal Study of Parents and Children (ALSPAC). This allowed the researchers to analyse their birth weights, birth length and growth throughout childhood.

The researchers found strong evidence that babies born with a low birth weight and short birth length were at increased risk of psychosis-like symptoms at 12 years of age. A one standard deviation increase in birth weight was associated with an 18% reduction in the risk of psychosis-like symptoms.

There was no evidence of a link between the children's growth during their early childhood, and psychotic symptoms at the age of 12.

The study findings echo previous research suggesting that a low birth weight is associated with an increased risk of schizophrenia in later life.

Thomas K, Harrison G, Zammit S, Lewis G, Horwood J, Heron J, Hollis C, Wolke D, Thompson A and Gunnell D (2009) Association of measures of fetal and childhood growth with non-clinical psychotic symptoms in 12-year-olds: the ALSPAC cohort, British Journal of Psychiatry, 194: 521-526