Falling IQ scores in childhood may signal psychotic disorders in later life

January 31, 2018, King's College London
Credit: CC0 Public Domain

New research shows adults who develop psychotic disorders experience declines in IQ during childhood and adolescence, falling progressively further behind their peers across a range of cognitive abilities. The researchers from King's College London's Institute of Psychiatry, Psychology & Neuroscience (IoPPN) and Icahn School of Medicine at Mount Sinai in the United States found falls in IQ start in early childhood, and suggest educational interventions could potentially delay the onset of mental illness.

Psychotic , such as schizophrenia, are severe mental illnesses affecting 1-3% of the UK population that cause a range of abnormalities in perception and thinking. The study, published today in JAMA Psychiatry, is the first to track IQ scores and throughout the entire first two decades of life among who develop psychotic disorders in adulthood.

Dr Josephine Mollon from King's IoPPN, now with Yale University, said: 'For individuals with psychotic disorders, does not just begin in adulthood, when individuals start to experience symptoms such as hallucinations and delusions, but rather many years prior - when difficulties with intellectual tasks first emerge - and worsen over time. Our results suggest that among adults with a psychotic disorder, the first signs of cognitive decline are apparent as early as age 4.'

Previous studies have shown that deficits in IQ begin many years before hallucinations and delusions first appear in patients with psychotic disorders, but the timing of when these IQ deficits emerge has not been clear. The new study provides the clearest evidence to date of early life cognitive decline in individuals with psychotic disorders.

The study included 4322 UK-based individuals who were followed from 18 months to 20 years old. Those who developed psychotic disorders as adults had normal IQ scores in infancy, but by age 4 their IQ started to decline, and continued to drop throughout childhood, adolescence and early adulthood until they were an average of 15 points lower than their healthy peers.

As well as falling behind in IQ, individuals who developed psychotic disorders lagged increasingly behind their peers in cognitive abilities such as working memory, processing speed and attention.

IQ scores fluctuate among healthy individuals, and not all children struggling at school are at risk of developing serious psychiatric disorders. Senior author Dr Abraham Reichenberg, Professor of Psychiatry at the Icahn School of Medicine at Mount Sinai and with King's IoPPN said: 'It is important to bear in mind that many children will experience some difficulties with schoolwork or other intellectual tasks at some point in their lives, and only a small minority will go on to develop a psychotic disorder.'

The results suggest that adults who develop psychotic disorders do not go through a deterioration in cognitive function, but instead they fail to keep up with normal developmental processes. Early interventions to improve cognitive abilities may potentially help stave off from developing in later life.

'There are early interventions offered to adolescents and young adults with psychosis,' said Dr Reichenberg. 'Our results show the potential importance of interventions happening much earlier in life. Intervening in childhood or early adolescence may prevent cognitive abilities from worsening and this may even delay or prevent illness onset.'

The researchers are now examining changes in the brains of individuals who go on to develop , as well as potential environmental and genetic risk factors that may predispose individuals to poor cognition.

Explore further: Risk of psychotic experiences up with teen cannabis use

More information: 'Course of Cognitive Development From Infancy to Early Adulthood in the Psychosis Spectrum' JAMA Psychiatry (2018). DOI: 10.1001/jamapsychiatry.2017.4327

Related Stories

Risk of psychotic experiences up with teen cannabis use

January 19, 2018
(HealthDay)—The risk of psychotic experiences is increased with cannabis use during adolescence, according to a study published online Jan. 17 in JAMA Psychiatry.

Decline in verbal ability in adolescence linked to psychosis in later life

January 22, 2013
(Medical Xpress)—New research from King's College London's Institute of Psychiatry and Karolinska Institutet, Sweden, has found that adolescents whose verbal performance drops off are at increased risk of developing schizophrenia ...

Frequent school moves can increase the risk of psychotic symptoms in early adolescence

February 18, 2014
Researchers at Warwick Medical School have shown that frequently moving schools during childhood can increase the risk of psychotic symptoms in later years.

Psychotic experiences put kids at higher suicide risk

August 30, 2017
Otherwise healthy people who experience hallucinations or delusions are more likely to have later suicidal thoughts or attempts, an international study has found.

People with psychotic-like experiences spend less time in healthy brain states

November 1, 2017
Healthy people experiencing subtle symptoms observed in psychotic disorders, such as hallucinations and delusions, have altered brain dynamics, according to a new study published in Biological Psychiatry: Cognitive Neuroscience ...

Marijuana may produce psychotic-like effects in high-risk individuals

September 13, 2017
Marijuana may bring on temporary paranoia and other psychosis-related effects in individuals at high risk of developing a psychotic disorder, finds a preliminary study from researchers at Columbia University Medical Center ...

Recommended for you

A depressed spouse may increase one's own cognitive decline, study finds

August 21, 2018
Researchers at Yale School of Public Health and their scientific partners have found that having a depressed spouse can increase one's own depressive symptoms as well as cognitive decline over time in late life. 

Study identifies 'compulsivity circuit' in heavy alcohol drinkers

August 21, 2018
Heavy alcohol drinkers attempt to acquire alcohol despite the threat of a negative consequence more so than light drinkers, a study in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging has found, and this behavior ...

Depressed patients see quality of life improve with nerve stimulation

August 21, 2018
People with depression who are treated with nerve stimulation experience significant improvements in quality of life, even when their depression symptoms don't completely subside, according to results of a national study ...

Beauty is simpler, and less special, than we realize

August 20, 2018
Beauty, long studied by philosophers, and more recently by scientists, is simpler than we might think, New York University psychology researchers have concluded in a new analysis. Their work, which appears in the journal ...

Bilingual children who speak native language at home have higher intelligence

August 20, 2018
Children who regularly use their native language at home while growing up in a different country have higher IQs, a new study has shown.

People are more honest when using a foreign tongue, research finds

August 17, 2018
New UChicago-led research suggests that someone who speaks in a foreign language is probably more credible than the average native speaker.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.