Inner ear disorders are often linked to the brain. A new study suggests that such conditions could be one of the causes of hyperactivity.
Hyperactivity is used to describe a physical state in which a person is abnormally active. Hyperactivity often forms part of a wider syndrome called Attention deficit hyperactivity disorder (ADHD). ADHD is a group of behavioral symptoms that include inattentiveness, hyperactivity and impulsiveness. It is a common condition in children, for which there are thought to be various triggers, including certain foods. A new area of research into the causes of hyperactivity is the connection between the ear and the brain.
This link between the brain, the inner ear, and hyperactive behavior has been shown in a study conducted in mice. The reason behind the study, the BBC reports, is because scientists have observed that children and teenagers with inner-ear disorders often have behavioral problems, especially conditions that affect hearing and balance.
The research showed that mice with inner ear conditions, like deafness or conditions that cause imbalance, are particularly active and continually exhibit behaviors like constantly chasing their tails.
Upon further analysis it was found that the mice with inner ear disorders and which displayed the hyperactive behavior had a genetic mutation, specially relating to the Slc12a2 gene. This gene is also found in people. It is thought that when the gene is affected, this leads to the elevation of some specific proteins (called pERK and pCREB).
A further set of studies were then performed where the gene's activity in the inner ears of healthy mice was blocked. This caused the mice to become increasingly active. However, when the mice were injected with the medicine haloperidol (used to treat tics), the behaviors returned to the normal. The medicine appeared to block the effects of the pERK and pCREB proteins.
Based on this, scientists think that there is a connection, and that the same effect occurs in people. This will be an area for further research.
The study was carried out at the Albert Einstein College of Medicine of Yeshiva University in New York and the findings have been published in the journal Science. The paper is titled "Causative Link Between Inner Ear Defects and Long-Term Striatal Dysfunction."