The researchers looked at more than 27,000 research papers to extract data from three types of studies: those addressing the progress of children known to have experienced adversity; studies of randomly selected members of the population; and research on psychotic patients who were asked about their early childhood.
Across all three types of studies, the results led to similar conclusions, according to the researchers. Children who had experienced any type of trauma before the age of 16 were approximately three times more likely to become psychotic in adulthood compared to those selected randomly from the population.
Researchers also found a relationship between the level of trauma and the likelihood of developing illness in later life. Those who were severely traumatized as children were at a greater risk, in some cases up to 50 times increased risk, than those who experienced trauma to a lesser extent.
The Liverpool researchers also conducted a new study that looked at the relationship between specific symptoms and the type of trauma experienced in childhood. They found that different traumas led to different symptoms. For example, childhood sexual abuse was associated with hallucinations, while being brought up in a children’s home was associated with paranoia.
The findings suggest that a patient’s life experiences need to be considered, along with neurological and genetic factors, said researcher and psychologist Dr. Richard Bentall.
“We need to know, for example, how childhood trauma affects the developing brain, as well as whether there are genetic factors that increase vulnerability or resilience to traumatic events,” he said.
“These questions will need new research strategies, such as studies comparing traumatized children who grow up to be psychologically healthy and those who go on to develop mental illness. Looking at the brain or genes only is unlikely to tell us what we need to know in order to treat a patient effectively.”
The researchers will now look at the psychological and brain processes involved in the links between different types of trauma and particular psychotic symptoms.
Future research will also aim to discover why symptoms of psychosis may only be expressed in later life, when the initial trigger many have been many years before in childhood.
The research is published in Schizophrenia Bulletin.
Source: University of Liverpool