Dopamine, reward and schizoid/avoidant personality disorder

This study found a strong link between abnormal dopamine function in the brain, and schizoid and avoidant behaviours. Dopamine is highly involved in sensations of pleasure, motivation, extroversion, sociability, aggression, and being emotional generally.

I know quite a few people that have either schizoid or avoidant PD, who say only dopamine-boosting drugs like amphetamine, GHB and opiates truly make them "normal". People with these disorders naturally have a high risk of addiction.

Association of polymorphisms of dopamine D2 receptor (DRD2), and dopamine transporter (DAT1) genes with schizoid/avoidant behaviors (SAB)

The dopaminergic system, and in particular the dopamine D2 receptor, has been implicated in reward mechanisms in the brain. Dysfunction of the D2 dopamine receptors leads to aberrant substance-seeking behaviors (ethanol, drugs, tobacco, and food) and other related behaviors (pathological gambling, Tourette's disorder, attention-deficit/hyperactivity disorder). This is the first study supporting a strong association between the dopamine D2 receptor Taq A1 allele with schizoid/avoidant behavior (SAB). Additionally, an albeit weaker association between the 480-bp VNTR 10/10 allele of the dopamine transporter (DAT1) gene with SAB was similarly found.
The article can be found here,