DPD/asthenic personality disorder is a personality abnormality characterised by the sufferers emotional and physical dependence on the people around them.
The cause is unknown.
Symptoms include inability to make decisions, passivity, avoiding isolation, fear of being abandoned, being easily hurt by criticism, avoiding responsibility, accepting decisions that they do not agree to, unwillingness to voice opinions, acceptance of abuse and a constant need to be in a relationship. A person with this disorder is more susceptible to alcohol and drug abuse, and physical or sexual abuse. 
PREVALENCE AND SUSCEPTIBILITY
It is present in 0.5% of the population. It is more frequent in females.
Medication can be prescribed to address attached problems with this disorder (eg. depression), but not to treat the disorder itself. Psychotherapy helps address the social maladjustment of the patient and self help groups can increase the patients confidence in themselves, though this can have a negative effect as they could become dependant on the group.
 - http://psychologytoday.com/conditions/antisocial.html
 - http://www.mind.org.uk/Information/Booklets/Understandin...
 - http://www.mayoclinic.com/health/personality-disorders/DS00562/DSECTION=2
 - http://www.mentalhealth.com/dis/p20-pe09.html
 - http:/www.nlm.nih.gov/medlineplus/ency/article/000941.htm