Young people living with a genetic alteration that increases the risk of psychiatric disorders have markedly different brain activity during sleep, a new study finds.
22q11.2DS is caused by a gene deletion of about 30 genes on chromosome 22 and occurs in 1 in 3000 births. It increases the risk of intellectual disability, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and seizures. It is also one of the greatest biological risk factors for schizophrenia. However, the biological mechanisms underlying psychiatric symptoms in 22q11.2DS are unclear.
“We recently showed that the majority of young people with 22q11.2DS have sleep problems, especially insomnia and sleep fragmentation, which are linked to psychiatric disorders,” said co-senior author Marianne van den Bree, professor of psychological medicine at the University of California. Cardiff. , UK. “However, our previous analysis was based on parents reporting on their children’s sleep quality, and the neurophysiology — what happens to brain activity — has not yet been explored.”
An established way to measure brain activity during sleep is an electroencephalogram (EEG). This measures electrical activity during sleep and includes patterns called spindles and slow-wave (SW) oscillations. These features are characteristic of non-rapid eye movement sleep (NREM) and are believed to promote memory consolidation and brain development. “Because sleep EEG is known to be altered in many neurodevelopmental disorders, the properties and coordination of these changes can be used as biomarkers of psychiatric dysfunction,” explains lead author Nick Donnelly, clinical lecturer in general adult psychiatry at the University of Bristol. UK
To investigate this in 22q11.2DS, the team recorded overnight sleep EEG in 28 youths 6-20 years old with the chromosome deletion and 17 unaffected siblings recruited as part of the Cardiff University Experiences of Children. with copy number variants (ECHO) research led by prof.dr. van den Bree. They measured correlations between sleep EEG patterns and psychiatric symptoms, as well as performance in a recall test the next morning.
They found that the group with 22q11.2DS had significant changes in sleep patterns, including a higher proportion of N3 NREM (slow-wave sleep) sleep and a lower proportion of N1 (the first and lightest stage of sleep) and rapid eye movement (REM) sleep. compared to their siblings. Those who carried the chromosome deletion also had increased EEG power for both slow-wave oscillations and spindles. There was also an increase in the frequency and density of coil patterns and a stronger coupling between the coil and slow-wave EEG features in the 22q112.DS group. These changes may reflect changes in the connections within and between areas of the brain that generate these oscillations, the cortex and the thalamus.
Participants also took part in a 2D object location task at bedtime, where they had to remember where matching maps were on a screen. They were tested again in the morning on the same task, and the team found that in those with 22q11.2DS, higher spindle and SW amplitudes were associated with lower accuracy. In contrast, in participants without the chromosome deletion, higher amplitudes were linked to higher accuracy in the morning recall test.
Finally, the team estimated the impact of the differences in sleep patterns on psychiatric symptoms in the two groups using a statistical method called mediation. They calculated the total effect of genotype on psychiatric measures and IQ, the indirect (mediated) effect of EEG measures, and then the proportion of the total effect that can be mediated by EEG patterns. They found that the effects on anxiety, ADHD and ASD caused by the 22q11.2 deletion were mediated in part by EEG differences in sleep.
“Our EEG findings together suggest a complex picture of sleep neurophysiology in 22q11.2DS and highlight differences that could serve as potential biomarkers for 22q11.2DS-associated neurodevelopmental syndromes,” concluded co-senior author Matt Jones, Professorial Research Fellow in Neuroscience, University of Bristol, UK. “Further research will now need to elucidate the relationship between psychiatric symptoms, sleep EEG measurements, and neurodevelopment, with a view to pinpointing markers of brain circuit dysfunction that could inform physicians which patients are most at risk, and support treatment decisions.” .”
Read all Latest lifestyle news and Important news here