Diagnosis
Clinicians and clinical researchers conceptualize dependent personality disorder in terms of four related components:

Cognitive: a perception of oneself as powerless and ineffectual, coupled with the belief that other people are comparatively powerful and potent. Motivational: a desire to obtain and maintain relationships with protectors and caregivers. Behavioral: a pattern of relationship-facilitating behavior designed to strengthen interpersonal ties and minimize the possibility of abandonment and rejection. Emotional: fear of abandonment, fear of rejection, and anxiety regarding evaluation by figures of authority. American Psychiatric Association and DSM
The Diagnostic and Statistical Manual of Mental Disorders (DSM) contains a dependent personality disorder diagnosis. It refers to a pervasive and excessive need to be taken care of which leads to submissive and clinging behavior and fears of separation. This begins prior to early adulthood and can be present in a variety of contexts.In the DSM Fifth Edition (DSM-5), there is one criterion by which there are eight features of dependent personality disorder. The disorder is indicated by at least five of the following factors:
Has difficulty making everyday decisions without an excessive amount of advice and reassurance from others. Needs others to assume responsibility for most major areas of their life. Has difficulty expressing disagreement with others because of fear of loss of support or approval. Has difficulty initiating projects or doing things on their own (because of a lack of self confidence in judgment or abilities rather than a lack of motivation or energy).
Frustration or over-gratification was said to result in an oral fixation and in an oral type of character, characterized by feeling dependent on others for nurturance and by behaviours representative of the oral stage. Later psychoanalytic theories shifted the focus from a drive-based approach of dependency to the recognition of the importance of early relationships and establishing separation from these early caregivers, in which the exchanges between the caregiver and the child become internalized, and the nature of these interactions becomes part of the concepts of the self and of others. References
Sources
Beck, Aaron T; Freeman, Arthur (1990). Cognitive Therapy of Personality Disorders. New York: Guilford Press. ISBN 978-0-89862-434-2. Millon, Theodore; Davis, Roger Dale (1996). Disorders of Personality: DSM-IV and Beyond. New York: Wiley. ISBN 978-0-471-01186-6. Millon, Theodore (1981). Disorders of Personality: DSM-III, Axis II. New York: Wiley. ISBN 978-0-471-06403-9. Perry, J. C. (1996). "Dependent personality disorder". In Gabbard, Glen O.; Atkinson, Sarah D. (eds.). Synopsis of Treatments of Psychiatric Disorders. American Psychiatric Press. pp. 995–998. ISBN 978-0-88048-859-4. Gjerde, L. C.; Czajkowski, N.; Røysamb, E.; Ørstavik, R. E.; Knudsen, G. P.; Østby, K.; Torgersen, S.; Myers, J.; Kendler, K. S.; Reichborn-Kjennerud, T. (2012). "The heritability of avoidant and dependent personality disorder assessed by personal interview and questionnaire". Acta Psychiatrica Scandinavica. 126 (6): 448–457. doi:10.1111/j.1600-0447.2012.01862.x. PMC 3493848. PMID 22486635. Millon, Theodore; Millon, Carrie M.; Meagher, Sarah; Grossman, Seth; Ramnath, Rowena (2004). Personality Disorders in Modern Life. Wiley. ISBN 978-0-471-66850-3. Millon, Theodore (2006). "Personality Subtypes". Kantor, Martin (1992). Diagnosis and Treatment of the Personality Disorders. Ishiyaku EuroAmerica. ISBN 978-0-912791-89-0.