Rett syndrome girls show detectable brain electrical activity changes

Patients have distinct EEG reading differences than typically developing peers

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Bolts of lightning shoots out of the bottom of a brain as if it's a storm cloud.

Girls with Rett syndrome have detectable abnormalities in the electrical activity in their brains, a new study confirms.

The study, “Abnormal spectral and scale-free properties of resting-state EEG in girls with Rett syndrome,” was published in Scientific Reports.

Brain cells communicate with each other by sending electrical signals down nerve fibers. A brain’s electrical activity can be measured using a technique called an electroencephalogram, or EEG.

Girls with Rett syndrome tend to have certain distinct differences in EEG readings compared to their typically developing peers, previous studies suggest. In this study, scientists in Russia conducted EEG tests to confirm and expand on the earlier reports.

“Previous studies showed several abnormalities in spontaneous EEG in RTT [Rett syndrome]. Here we plan to verify them in an independent sample of girls with RTT,” they wrote.

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Differences in EEG readings in brain of girls with Rett syndrome

The study included 23 girls with Rett syndrome, ranging in age from 3-17. EEG readings of 38 typically developing children were collected as controls. While all the Rett patients were girls, the control group included a few boys, which the researchers noted as a limitation of the analysis.

EEG readings were done for all the participants while they wore a mask over their eyes so they couldn’t see anything since being able to view something can cause electrical activity in the brain.

The Rett patients had an increase in theta power (a type of EEG measurement) in the front and central portions of the brain. In this measure, the difference between Rett girls and typically developing children tended to become more dramatic in older participants, suggesting the difference increases over time as the condition progresses.

Patients also showed a decrease in alpha power, another EEG measurement, in multiple brain regions. A third measurement, gamma power, was observed to increase in several areas of the Rett brain.

“We confirmed some previous findings of a few previous quantitative EEG studies such as increased theta and decreased alpha power,” the scientists wrote, adding these data indicate a “general slowing of background activity” in Rett brains.

Rett patients also showed some statistically significant differences in long-range temporal correlations (LRTC), which measures the ability of neural networks to integrate information over time. LRTC hasn’t been specifically investigated in Rett patients before, the researchers said.

After collecting the EEG data, the scientists conducted statistical tests to evaluate whether the data could accurately distinguish between typically developing children and those with Rett. The team calculated the area under the receiver operating characteristic curve, which is a statistical measure that tests how well a given criteria can differentiate between two groups. Values can range from 0.5 to 1 with higher numbers reflecting a better ability to tell the difference. Here the value was 0.92, suggesting a very high ability to differentiate.

“Overall, parameters of EEG … allowed segregating RTT from [typically developing children] with high accuracy,” the scientists said.