The orbitofrontal cortex (OFC) is a prefrontal cortex region in the frontal lobes in the brain and it is located just above the eyes. It has been proposed that the OFC is involved in sensory integration, in representing the affective value of reinforcers, and in decision-making and expectation. One clear extension of problems with decision-making is drug addiction/substance dependence, which can result from disruption of the striato-thalamo-orbitofrontal circuit. OFC connectivity disruptions may cause, impulsivity, personality changes and hyperactivity Identifying Information: OD, 19 year-old white male, single, unemployed, dropped out sophomore year of high school, he is the second of three siblings. Chief Complaint: Lighter şuid and cannabis consumption. History of Present Illness (HPI): There was no complaint until 2009. Slowness of movement and stillness complaints began in December, 2009. Metronidazole treatment was initiated for diarrhea and followed by aphasia, seizures, headaches, urinary incontinence, lethargy, inability to walk in. He was admitted to intensive care unit for 42 days. During this period, cranial MRI was conducted which revealed bilateral symmetrical diffuse involvement of the basal ganglia at the level of caudate nuclei. Psychiatric Examination: General Impression: Appearance older than biological age, decrease in self-care, attired appropriately, nonsensitiveness. Mood: euthymic, Affect: distressed, anxious. Perception: Auditory and visual hallucinations under the inşuence of lighter şuid Cognition: Fully oriented. Record: 3/3, Recall: 2/3 Interviews with his parents revealed dramatic personality changes. While he was a kind, sympathetic, coherent, respectful, shy, responsible person, immediately after discharge from intensive care unit, he had hyperbulemia, excessive drinking (juice and coke), been tense, impatient, irascible, using foul language, demonstrating inappropriate behaviors, improper speech content, excessive interest in pornography even in public, talkativeness, restlessness. Specifically, he had been abusing boys between the ages of 5-6 overtly, even in the presence of their parents. He had been abusing lighter gas and synthetic cannabinoid approximately a year after his intensive care unit stay and personality changes. Neurocognitive Tests: Digit Span revealed general weakness in attention and concentration, Wechsler Memory Scale revealed mild to medium impairment on visual recall and Benton Visual Retention Test performance was close to lower range limit. Wisconsin Card Sorting Test, Stroop Test, IOWA Gambling Task, Reading Mind in the Eyes Test and Go-no-Go test performances were all in normal ranges. Diagnosis: F19.2 Mental and behavioral disorders due to multiple drug use and use of other psychoactive substances; F07,0 Organic personality disorder. Orbitofrontal cortex additionally share highly complex reciprocal connections with the sensory cortices, limbic areas, amygdala, and hypothalamus. When OFC connections are disrupted, varying cognitive, behavioral, and emotional consequences may arise. Previous studies has demonstrated personality changes in individuals with orbitofrontal cortex lesions. Phineas Gage, a well known case, had became fitful, irreverent, impatient of restraint, capricious and vacillating after a major head trauma. It might be concluded that similar personality changes also took place in our case. OFC has intense and complex connections with a wide range of other brain regions, which might have lead to complex nature of complaints in our case.