Some studies conducted on ADHD have found a statistically significant relationship between those diagnosed with the disorder and a higher susceptibility to abuse alcohol. However, other studies have found no such correlation, or have found this to be true of only a nonstatistically significant subset of the population of individuals with ADHD. This research found an answer to what may be causing these discrepancies in findings. Various studies on ADHD have discovered both biological and cognitive differences in some individuals with ADHD that may be responsible for this predisposition toward alcohol abuse found in a subset of the ADHD population. It is proposed that those individuals diagnosed with ADHD who also have a mutation in the dopamine receptor D4 ("DRD4") and who possess a deficiency in functionality of the prefrontal area of the brain designed for planning and reasoning may be more likely to develop alcohol abuse.