Genetics
There are several difficulties when it comes to trying to identify a gene for complex traits such as impulsivity, such as genetic heterogeneity. Another difficulty is that the genes in question might sometimes show incomplete penetrance, "where a given gene variant does not always cause the phenotype". Much of the research on the genetics of impulsivity-related disorders, such as ADHD, is based on family or linkage studies. There are several genes of interest that have been studied in an attempt to find the major genetic contributors to impulsivity. Some of these genes are:
- DAT1 is the dopamine transporter gene which is responsible for the active reuptake of dopamine from the neural synapse. DAT1 polymorphisms have been shown to be linked to hyperactivity and ADHD.
-
- DRD4 is the dopamine D4 receptor gene and is associated with ADHD and novelty seeking behaviors. It has been proposed that novelty seeking is associated with impulsivity. Mice deficient for DRD4 have shown less behavioral responses to novelty.
-
- 5HT2A is the serotonin receptor gene. The serotonin 2A receptor gene has been associated with both hyper locomotion, ADHD, as well as impulsivity. Subjects with a particular polymorphism of the 5HT2A gene made more commission errors during a punishment-reward condition in a go/no-go task.
-
- HTR2B a serotonin receptor gene.
-
- CTNNA2 encodes for a brain-expressed α-catenin that has been associated with Excitement-Seeking in a genome-wide association study GWAS of 7860 individuals.
Read more about this topic: Impulsivity