In advanced cases, depression may result in self-inflicted injury and could even lead to suicide. Some people have reported relief from depression or manic symptoms after theft.It has been suggested that because kleptomania is linked to strong compulsive and impulsive qualities, it can be viewed as a variation of obsessive-compulsive spectrum disorders, together with pathological gambling, compulsive buying, pyromania, nailbiting and trichotillomania. This point achieves support from the unusually higher cases of obsessive-compulsive disorder (OCD; see below) in close relatives of patients with kleptomania. Substance use disorder
Kleptomania and drug addictions seem to have central qualities in common, including:

recurring or compulsive participation in a behavior in spite of undesirable penalties;
weakened control over the disturbing behavior;
a need or desire condition before taking part in the problematic behavior; and
a positive pleasure-seeking condition throughout the act of the disturbing behavior.Data from epidemiological studies additionally propose that there is an affiliation between kleptomania and substance use disorders along with high rates in a unidirectional manner. Phenomenological data maintain that there is a relationship between kleptomania and drug addictions. A higher percentage of cases of kleptomania has been noted in adolescents and young adults, and a lesser number of cases among older adults, which imply an analogous natural history to that seen in substance use disorders. Family history data also propose a probable common genetic input to alcohol use and kleptomania. Substance use disorders are more common in kin of persons with kleptomania than in the general population.
Biological models
Biological models explaining the origins of kleptomania have been based mostly on pharmacotherapy treatment studies that used selective serotonin reuptake inhibitors (SSRIs), mood stabilizers, and opioid receptor antagonists.Some studies using SSRIs have observed that opioid antagonists appear to reduce the urge to steal and mute the "rush" typically experienced immediately after stealing by some subjects with kleptomania. This would suggest that poor regulation of serotonin, dopamine, and/or natural opioids within the brain are to blame for kleptomania, linking it with impulse control and affective disorders.An alternative explanation too based on opioid antagonist studies states that kleptomania is similar to the "self-medication" model, in which stealing stimulates the persons natural opioid system. "The opioid release soothes the patients, treats their sadness, or reduces their anxiety. Thus, stealing is a mechanism to relieve oneself from a chronic state of hyperarousal, perhaps produced by prior stressful or traumatic events, and thereby modulate affective states. ": 354

Diagnosis
Disagreement surrounds the method by which kleptomania is considered and diagnosed. On one hand, some researchers believe that kleptomania is merely theft and dispute the suggestion that there are psychological mechanisms involved, while others observe kleptomania as part of a substance-related addiction. Yet others categorize kleptomania as a variation of an impulse control disorder, such as obsessive-compulsive disorder or eating disorders.