Kids and adolescents with ADHD often struggle to keep their emotions in check. ADHD has also been linked to sleep disorders, which is one of the reasons a team of German researchers sought to determine how sleep influences the consolidation and processing of emotional memories.
Brain imaging studies have shown that ADHD alters the structure and functions of areas of the brain important to processing emotions, like the prefrontal cortex, the amygdala and the hippocampus. Scientists have speculated that a disrupted connection between these areas of the brain could contribute to a patient’s day-to-day emotions.
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Among healthy children and adults, sleep facilitates the processing of emotional stimuli, so the researchers wanted to see if there were processing differences between healthy study subjects and participants with ADHD. For their study, researchers led by Alexander Prehn-Kristensen of University Hospital Schleswig-Holstein analyzed the emotional memory processing of 16 children with ADHD, 16 healthy children and 20 healthy adults.
In the study, the participants were shown photos that were either emotionally negative, like a snake or growling bear, or emotionally neutral, like an umbrella or lamp. Previous research has shown that emotionally charged images usually have a greater brain response, and are more likely to be remembered.
“During daytime, people suffering from ADHD often have problems focusing on the relevant information and ignoring irrelevant information. Here, we wanted to look whether the described daytime problem in contrasting between relevant and irrelevant information is also observable during sleep,” says study author Alexander Prehn-Kristensen, study researcher from Christian-Albrecht-university in Kiel, Germany in an email response.
All the participants were shown the photos in the evening and had their sleep monitored by the researchers using electroencephalogram (EEG) measurements to track brain activity. The next day, the participants were tested on their recollection of the emotion-inducing images.
The healthy kids without ADHD were better able to recall the images compared to the kids with ADHD and even the healthy adults. These kids had higher activity in the frontal region of their brain and could remember the emotional images better than the neutral ones. Emotional experiences are typically easier to remember than neutral memories.
Prehn-Kristensen says more research is necessary before any therapeutic or clinical conclusions should be drawn. Since the children’s memories were observed in an artificial context, they cannot presume these results carry over to day-to-day memory experiences. However, they do shed light on how brain activity issues during sleep could be responsible for emotional processing for kids with ADHD.
The study is published in the journal PLOS ONE.