Researchers from Norway report that they have found a rat model for the Predominantly Inattentive subtype of ADHD (ADHD-PI). This type of ADHD is characterized by Inattention without hyperactivity or impulsiveness. The researcher reported in Neuropharmacology (2009 Dec;57), that “The WKY rat obtained from Charles River Germany provides a promising model for the predominantly inattentive subtype of ADHD.”
Inattentive ADHD is less common than Hyperactive/Impulsive ADHD (ADHD-HI). It affects a great many people but it gets less attention than ADHD-HI because the symptoms are less obvious and less disruptive to the every day functioning of classrooms and family life. The inattentive type of ADHD is disabling in a different way than the Hyperactive/Impulsive subtype. The discovery of this animal model will help researchers learn more about this subtype of add symptoms.
We know that ADHD is genetic, it runs in families and is 80% inheritable. An animal with similar genes will respond to treatment similarly to a human with the same gene problem. The researchers will study the gene structure of the WKY rat to gain a better understanding of the genetics involved in ADHD-PI.
Several years ago researcher found that the spontaneously hypertensive rat (SHR) displayed all the main symptoms of ADHD/HI (Hyperactive/Impulsive sub-type) and that this rat also had the predicted disturbances in the brain’s nervous system when they were compared to a rat with no ADHD symptoms.
The discovery of an animal model for ADHD-PI is an exiting finding as finally ADHD-PI can be more thoroughly studied. Treatment studies almost always use animals for testing first. If the treatment shows promise in the animal then the study moves on to human testing. Without an animal model for ADHD-PI, promising treatment possibilities cannot be explored.
There is some thought though that it is not only genes that are important but that both the environment and genes play a role in all types of ADHD. They have used rats to look at the influence of environment as well as the influence of genes. Another study of rats was done in South Africa using SHR rats that were mothered by rats without ADHD/HI or ADHD/C (Combined sub-type). This study found that mothering had no impact on the ADHD behavior of rats with ADHD/HI or the behavior of rats with ADHD/C. Studies such as this one will be performed using the WKY Rat and will give us further insight into the roll the environment plays in people with Inattentive ADHD.
The WKY rat obtained from Charles River Germany provides a promising model for the predominantly inattentive subtype of ADHD.” The inattentive type of ADHD is disabling in a different way than the Hyperactive/Impulsive subtype of ADHD. The discovery of this animal model will help researchers learn more about Predominantly Inattentive ADHD.