Organic Personality Disorder:
Organic Personality Disorder is characterize by a significant alteration of the habitual patterns of behaviour displayed by the subject premorbidly, involving the expression of emotions, needs and impulses. Impairment of cognitive and thought functions, and altered sexuality may also be part of the clinical picture. 
Organic personality disorder causes people to exhibit anti-social or harmful behaviors that they are not usually know for exhibiting. 
Organic personality disorder centers around short or long-term personality disturbances that are cause by a physical malfunction of the brain. While most people who suffer from the symptoms of organic personality disorder are able to function in society productively, some do have problems when they are not under constant supervision. 
The organic personality disorder is characterised by a signiﬁcant alteration of the premorbid personality caused by an underlying organic cause without major disturbance of consciousness, orientation, memory or perception.
The personality change may be characterised by poor impulse control, emotional lability, apathy, accentuation of earlier personality traits, or hostility.
According to ICD-10 (F07.0), the following features are required for diagnosis of organic personality disorder, in addition to the general guidelines. 
Sign & Symptoms:
In addition to an established history or other evidence of brain disease, damage, or dysfunction, a deﬁnitive diagnosis requires the presence of two or more of six features described.
- Consistently reduced ability to persevere with goal-directed activities
- Altered emotional behaviour (emotional lability, euphoria, inappropriate jocularity, irritability or short-lived anger outbursts)
- Expression of needs and impulses without consideration of the consequences
- Cognitive disturbances (such as suspiciousness, paranoid ideation, and/or excessive preoccupation with a single theme)
- Marked alteration of language production (such as circumstantiality, over-inclusiveness, viscosity, and hypergraphia)
- Altered sexual behaviour 
- Sudden changes in behavior
- Inappropriate social behavior
- Sexual indiscretions
- Emotional instability
- Bad social judgement
- Belligerence and an overactive temper. 
1. Temporal lobe epilepsy (complex partial seizures) which can be associated with temporal lobe (personality) syndrome.
2. Concussion ( postconcussional syndrome).
3. Encephalitis (postencephalitis syndrome).
4. Multiple sclerosis (early).
5. Cerebral neoplasms, especially in frontal lobe (frontal lobe syndromes) and parietal lobe.
6. Cerebrovascular disease.
7. Psychoactive drugs (rarely). 
8. Extreme trauma to the head is another possible cause for the sudden appearance of a personality disorder.
9. In rare cases, thyroid disease or other problems with the brain may cause personality disorder.
Whatever the root cause, it is important to seek out someone who knows what how to help a person deal with all of the symptoms and side effects that come with organic personality disorder. 
Some syndroms are discribed below:
1. Frontal lobe syndrome:
a. Orbito-frontal syndrome (Pseudo-psychopathic): Disinhibition, jocularity, impulsivity, impaired insight and judgement.
b. Frontal convexity type (Pseudo-depressive): Apathy, lack of initiative, retardation, perseveration.
c. Medial frontal syndrome (Akinetic): Akinesis, incontinence, poor verbal output.
2. Temporal lobe syndrome:
Egocentricity, explosive affect, perseveration, excessive religiosity, obsessional traits.
3. Bilateral temporal lobe or limbic system lesions:
Emotional placcidity, hyper-orality, altered sexual behaviour, excessive exploration of environment (hyper-metamorphosis). 
1. Treatment of the underlying cause, if treatable.
2. Symptomatic treatment, with lithium or carbamazepine for aggressive behaviour and impulse dyscontrol, and/or antipsychotics (occasionally) for violent behaviour may be needed.