Despite recent initiatives to study psychopathology along dimensions of behavior and neurobiological indices, which would help refine a clearer picture of the development and treatment of externalizing disorders, the majority of research has examined specific mental disorders. Thus, best practices for many externalizing disorders are disorder-specific. For example, substance use disorders themselves are very heterogeneous and their best-evidenced treatment typically includes cognitive behavioral therapy, motivational interviewing, and a substance disorder-specific detoxification or psychotropic medication treatment component. The best-evidenced treatment for childhood conduct and externalizing problems more broadly, including youth with ADHD, ODD, and CD, is parent management training, a form of cognitive behavioral therapy. Additionally, individuals with ADHD, both youth and adults, are frequently treated with stimulant medications (or alternative psychotropic medications), especially if psychotherapy alone has not been effective in managing symptoms and impairment. Psychotherapy and medication interventions for individuals with severe, adult forms of antisocial behavior, such as antisocial personality disorder, have been mostly ineffective. An individual's comorbid psychopathology may also influences the course of treatment for an individual.

As it has already been mentioned, patients with organic personality disorder show a wide variety of sudden behavioural changes and dysfunctions. There are not a lot of information about the treatment of this mental health disorder. The pharmacological approach is the most common therapy among patients with organic personality disorder. However, the choice of drug therapy relies on the seriousness of patient's situation and what symptoms are shown. The choice and administration of specific drugs contribute to the reduction of symptoms of organic personality disorder. For this reason, it is crucial for patients' treatment to be assessed by clinical psychologists and psychiatrists before the administration of drug.

Additionally, the dysfunctions in expression of behaviour of patients with organic personality disorder and the development of symptom of irritability, which are caused by aggressive and self-injurious behaviours, can be dealt with the administration of carbamazepine. Moreover, the symptoms of this disorder can be decreased by the administration of valproic acid. Also, emotional irritability and signs of depression can be dealt with the use of nortriptyline and low-dose thioridazine. Except from the symptom of irritability, patients express aggressive behaviours. At the onset of drug therapy for effective treatment of anger and aggression, the drug of carbamazepine, phenobarbital, benztropine and haloperidol can be administrated in order to reduce the symptoms of patients with organic personality disorder. In addition, the use of propranolol may decrease the frequent behaviours of rage attacks.

Finally, it is important for patients to take part in psychotherapy sessions during the period of drug therapy. In this way, there is prevention and patients can be protected by negative effects of drugs on their organism and their behaviour. Furthermore, the clinicians can provide useful and helpful support to patients during these psychotherapy sessions. Thus, the combination of drug therapy with psychotherapy can lead to the reduction of symptoms of this disorder and the improvement of patients' situation.

There is no cure for ASD and proper treatment depends on the case and what is most struggled with. Autism spectrum disorder is like many other disorders where when diagnosed early, can be better treated. Different types of therapy are helpful such as music therapy and physical therapy. Other treatments include auditory training, discrete trial training, facilitated communication, and sensory integration therapy.

Treatment of ADHD often includes a combination of psychological, behavioural, pharmaceutical and educational advice and interventions.

Medications commonly used in the treatment of ADHD are primarily stimulants such as methylphenidate and lisdexamphetamine and non-stimulants such as atomoxetine.

SSRI antidepressants may be unhelpful, and could worsen symptoms of ADHD.

However ADHD is often misdiagnosed as depression, particularly when no hyperactivity is present.

Externalizing disorders are frequently comorbid or co-occurring with other disorders. Individuals who have the co-occurrence of more than one externalizing disorder have homotypic comorbidity, whereas individuals who have co-occurring externalizing and Internalizing disorders have heterotypic comorbidity. It is not uncommon for children with early externalizing problems to develop both internalizing and further externalizing problems across the lifespan.

Although medication is the first-line treatment for most psychiatric disorders, it does not always improve every aspect of a patient's life, and for the negative symptoms in schizophrenia, the responses to anti-psychotics are less favourable than for positive symptoms. As a result, psychotherapy might be an alternative for the treatment of these symptoms, even if medication has a good effect on other manifestations of the disorder.

Cognitive behavioural therapy (CBT), is the kind of psychotherapy that shows most promise in treating avolition (and other negative symptoms of schizophrenia), but more research is needed in the area. CBT focuses on understanding how thoughts and feelings influence behaviour, in order to help individuals develop methods and strategies to better handle the implications of their disorder. Some research suggests that CBT focusing on social skills and practice of interpersonal situations, like job interviews, seeing a doctor (to discuss medication, for example), or interacting with friends and co-workers, as well as seemingly simple things like riding a bus, might reduce negative symptoms of schizophrenia and be beneficial to patients with avolition.

Other forms of psychotherapy might also complement the role of medication and help patients, their families, and friends to work through emotional and other challenges of living with a chronic psychological disorder, including avolition.

The 2004 WHO report "Prevention of Mental Disorders" stated that "Prevention of these disorders is obviously one of the most effective ways to reduce the [disease] burden."

The 2011 European Psychiatric Association (EPA) guidance on prevention of mental disorders states "There is considerable evidence that various psychiatric conditions can be prevented through the implementation of effective evidence-based interventions."

A 2011 UK Department of Health report on the economic case for mental health promotion and mental illness prevention found that "many interventions are outstandingly good value for money, low in cost and often become self-financing over time, saving public expenditure".

In 2016, the National Institute of Mental Health re-affirmed prevention as a research priority area.

Parenting may affect the child's mental health, and evidence suggests that helping parents to be more effective with their children can address mental health needs.

Universal prevention (aimed at a population that has no increased risk for developing a mental disorder, such as school programs or mass media campaigns) need very high numbers of people to show effect (sometimes known as the "power" problem). Approaches to overcome this are (1) focus on high-incidence groups (e.g. by targeting groups with high risk factors), (2) use multiple interventions to achieve greater, and thus more statistically valid, effects, (3) use cumulative meta-analyses of many trials, and (4) run very large trials.

Risk factors for mental illness include genetic inheritance, such as parents having depression, or a propensity for high neuroticism or "emotional instability".

In depression, parenting risk factors include parental unequal treatment, and there is association with high cannabis use.

In schizophrenia and psychosis, risk factors include migration and discrimination, childhood trauma, bereavement or separation in families, and abuse of drugs, including cannabis, and urbanicity.

In anxiety, risk factors may include family history (e.g. of anxiety), temperament and attitudes (e.g. pessimism), and parenting factors including parental rejection, lack of parental warmth, high hostility, harsh discipline, high maternal negative affect, anxious childrearing, modelling of dysfunctional and drug-abusing behaviour, and child abuse (emotional, physical and sexual).

Environmental events surrounding pregnancy and birth have also been implicated. Traumatic brain injury may increase the risk of developing certain mental disorders. There have been some tentative inconsistent links found to certain viral infections, to substance misuse, and to general physical health.

Social influences have been found to be important, including abuse, neglect, bullying, social stress, traumatic events and other negative or overwhelming life experiences. For bipolar disorder, stress (such as childhood adversity) is not a specific cause, but does place genetically and biologically vulnerable individuals at risk for a more severe course of illness. The specific risks and pathways to particular disorders are less clear, however. Aspects of the wider community have also been implicated, including employment problems, socioeconomic inequality, lack of social cohesion, problems linked to migration, and features of particular societies and cultures.

It is possible for this disorder to progress over time. A patient suffering from the disorder can improve the condition with treatments. There are several types of therapies that may improve the condition, but depending on a patient’s experience of the disorder or the cause of the disorder, treatments will vary.

- Psychotherapy including behaviour therapy, Gestalt therapy, Adlerian therapy, psychoanalytic therapy and existential therapy.

- Pharmacotherapy through medications including antidepressants.

The self-medication theory suggests that people with severe mental illnesses misuse substances in order to relieve a specific set of symptoms and counter the negative side-effects of antipsychotic medication.

Khantizan proposes that substances are not randomly chosen, but are specifically selected for their effects. For example, using stimulants such as nicotine or amphetamines can be used to combat the sedation that can be caused by higher doses of certain types of (usually typical) antipsychotic medication. Conversely, some people taking medications with a stimulant effect such as the SNRI antidepressants Effexor (venlafaxine) or Wellbutrin (bupropion) may seek out benzodiazepines or opioid narcotics to counter the anxiety and insomnia that such medications sometimes evoke.

Some studies show that nicotine administration can be effective for reducing motor side-effects of antipsychotics, with both bradykinesia (stiff muscles) and dyskinesia(involuntary movement) being prevented.

Currently, genetic research for the understanding of the development of personality disorders is severely lacking. However, there are a few possible risk factors currently in discovery. Researchers are currently looking into genetic mechanisms for traits such as aggression, fear and anxiety, which are associated with diagnosed individuals. More research is being conducted into disorder specific mechanisms.

The past exposure theory suggests that exposure to psychiatric medication alters neural synapses, introducing an that was not previously present. Discontinuation of the drug is expected to result in symptoms of psychiatric illness which resolve once the drug is restarted. This theory suggests that while it may appear that the medication is working, it is only treating a disorder caused by the medication itself. New exposure to psychiatric medication may lead to heightened sensitivity to the effects of drugs and alcohol, which has a deteriorating effect on the patient.

Psychotherapy, more specifically, cognitive behavioral therapy (CBT), is the most widely used form of treatment for Somatic symptom disorder. In 2016, a randomized 12-week study suggested steady and significant improvement in health anxiety measures with cognitive behavioral therapy compared to the control group.

CBT can help in some of the following ways:

- Learn to reduce stress

- Learn to cope with physical symptoms

- Learn to deal with depression and other psychological issues

- Improve quality of life

- Reduce preoccupation with symptom

Moreover, brief psychodynamic interpersonal psychotherapy (PIT) for patients with multisomatoform disorder has shown its long-term efficacy for improving the physical quality of life in patients with multiple, difficult-to-treat, medically unexplained symptoms.

Antidepressant medication has also been used to treat some of the symptoms of depression and anxiety that are common among people who have somatic symptom disorder. Medications will not cure somatic symptom disorder, but can help the treatment process when combined with CBT.

There are many different forms (modalities) of treatment used for personality disorders:

- Individual psychotherapy has been a mainstay of treatment. There are long-term and short-term (brief) forms.

- Family therapy, including couples therapy.

- Group therapy for personality dysfunction is probably the second most used.

- Psychological-education may be used as an addition.

- Self-help groups may provide resources for personality disorders.

- Psychiatric medications for treating symptoms of personality dysfunction or co-occurring conditions.

- Milieu therapy, a kind of group-based residential approach, has a history of use in treating personality disorders, including therapeutic communities.

- The practice of mindfulness that includes developing the ability to be nonjudgmentally aware of unpleasant emotions appears to be a promising clinical tool for managing different types of personality disorders.

There are different specific theories or schools of therapy within many of these modalities. They may, for example, emphasize psychodynamic techniques, or cognitive or behavioral techniques. In clinical practice, many therapists use an 'eclectic' approach, taking elements of different schools as and when they seem to fit to an individual client. There is also often a focus on common themes that seem to be beneficial regardless of techniques, including attributes of the therapist (e.g. trustworthiness, competence, caring), processes afforded to the client (e.g. ability to express and confide difficulties and emotions), and the match between the two (e.g. aiming for mutual respect, trust and boundaries).

Avolition, as a symptom of various forms of psychopathology, is the decrease in the motivation to initiate and perform self-directed purposeful activities. Such activities that appear to be neglected usually include routine activities, including hobbies, going to work and/or school, and most notably, engaging in social activities. A person experiencing avolition may stay at home for long periods of time, rather than seeking out work or peer relations.

Before delirium treatment, the cause must be established. Medication such as antipsychotics or benzodiazepines can help reduce the symptoms for some cases. For alcohol or malnourished cases, vitamin B supplements are recommended and for extreme cases, life-support can be used.

As it has already been mentioned, the organic personality disorder is included in a wide group of personality and behavioural disorders. This mental health disorder can be caused by disease, brain damages or dysfunctions in specific brain areas in frontal lobe. The most common reason for this profound change in personality is the traumatic brain injury (TBI). Children, whose brain areas have injured or damaged, may present Attention Deficit Hyperactivity Disorder (ADHD), oppositional defiant disorder (ODD) and organic personality disorder. Moreover, this disorder is characterised as "frontal lobe syndrome". This characteristic name shows that the organic personality disorder can usually be caused by lesions in three brain areas of frontal lobe. Specifically, the symptoms of organic personality disorder can also be caused by traumatic brain injuries in orbitofrontal cortex, anterior cingulate cortex and dorsolateral prefrontal cortex. It is worth to be mentioned that organic personality disorder may also be caused by lesions in other circumscribed brain areas.

There is no cure for neurocognitive disorder or the diseases that cause it. Antidepressants, antipsychotics, and other medications that treat memory loss and behavioral symptoms are available and may help to treat the diseases. Ongoing psychotherapy and psychosocial support for patients and families are usually necessary for clear understanding and proper management of the disorder and to maintain a better quality of life for everyone involved. Speech therapy has been shown to help with language impairment.

Studies suggest that diets with high Omega 3 content, low in saturated fats and sugars, along with regular exercise can increase the level of brain plasticity. Other studies have shown that mental exercise such a newly developed “computerized brain training programs” can also help build and maintain targeted specific areas of the brain. These studies have been very successful for those diagnosed with schizophrenia and can improve fluid intelligence, the ability to adapt and deal with new problems or challenges the first time encountered, and in young people, it can still be effective in later life.

A person with amnesia may slowly be able to recall their memories or work with an occupational therapist to learn new information to replace what was lost, or to use intact memories as a basis for taking in new information. If it is caused by an underlying cause such as Alzheimer's disease or infections, the cause may be treated but the amnesia may not be.

Among the psychological assessments for identifying whether or not children and adolescents are experiencing depression and/or depressive symptoms is the Children's Depression Inventory. In early 2016, the USPSTF released an updated recommendation for the screening of adolescents ages 12 to 18 years for major depressive disorder (MDD). Appropriate treatment and follow-up should be provided for adolescents who screen positive.

Cognitive-behavioural therapy (CBT) is a frequently suggested treatment for executive dysfunction, but has shown limited effectiveness. However, a study of CBT in a group rehabilitation setting showed a significant increase in positive treatment outcome compared with individual therapy. Patients' self-reported symptoms on 16 different ADHD/executive-related items were reduced following the treatment period.

Dependent personality disorder occurs in about 0.6% of the general population. The disorder is diagnosed more often in females than males; however, research suggests that this is largely due to behavioural differences in interviews and self-reporting rather than a difference in prevalence between the sexes. A 2004 twin study suggests a heritability of 0.81 for developing dependent personality disorder. Because of this, there is significant evidence that this disorder runs in families. Children and adolescents with a history of anxiety disorders and physical illnesses are more susceptible to acquiring this disorder.

Professionals first became aware of child abuse in the early 1980s, so it is possible that some of the young people identified with depressive disorders may have had a history of sexual abuse, which was not disclosed. This raises the question of what the outcome would have been in those young people if they had disclosed the abuse and received appropriate therapeutic interventions. It is well-known that childhood sexual abuse is a significant factor in the history of some adults with depressive syndromes.

In the past, attention deficit hyperactivity disorder (ADHD) was not recognized, and hyperkinetic disorder was only rarely diagnosed. Some young people, especially those with co-morbid conduct disorder and major depressive disorder, may have had undiagnosed and untreated ADHD. Before the use of psycho-stimulants, some young people may have been more vulnerable to development of depressive syndromes because of untreated attentional and other behavioural problems which reduce their self-esteem.

Although antidepressants were used by child and adolescent psychiatrists to treat major depressive disorder, they may not always have been used in young people with a comorbid conduct disorder because of the risks of overdose in such a population. Tricyclic antidepressant were the predominant antidepressants used at that time in this population. With the advent of selective serotonin re-uptake inhibitors (SSRIs), child and adolescent psychiatrists probably began prescribing more anti-depressants in the co-morbid conduct disorder/major depressive group because of the lower risk of serious harm in overdose. This raises the possibility that more effective treatment of these young people might also improve their outcomes in adult life.

Impulse-control disorders have two treatment options: psychosocial and pharmacological. Treatment methodology is informed by the presence of comorbid conditions.

Treatment requires a firm and transparent diagnosis based on positive features which both health professionals and patients can feel confident about. It is essential that the health professional confirms that this is a common problem which is genuine, not imagined and not a diagnosis of exclusion.

Confidence in the diagnosis does not improve symptoms, but appears to improve the efficacy of treatments such as physiotherapy which require altering established abnormal patterns of movement.

A multi-disciplinary approach to treating functional neurological disorder is recommended.

Treatment options can include:

- Physiotherapy and occupational therapy

- Medication such as sleeping tablets, painkillers, anti-epileptic medications and anti-depressants (for patients suffering with depresssion co-morbid or for pain relief)

Physiotherapy with someone who understands functional disorders may be the initial treatment of choice for patients with motor symptoms such as weakness, gait (walking) disorder and movement disorders. Nielsen et al. have reviewed the medical literature on physiotherapy for functional motor disorders up to 2012 and concluded that the available studies, although limited, mainly report positive results. Since then several studies have shown positive outcomes. In one study, up to 65% of patients were very much or much improved after five days of intensive physiotherapy even though 55% of patients were thought to have poor prognosis. In a randomised controlled trial of physiotherapy there was significant improvement in mobility which was sustained on one year follow up. In multidisciplinary settings 69% of patients markedly improved even with short rehabilitation programmes. Benefit from treatment continued even when patients were contacted up 25months after treatment.

For patients with severe and chronic FND a combination of physiotherapy, occupational therapy and cognitive behavioural therapy may be the best combination with positive studies being published in patients who have had symptoms for up to three years before treatment.

Cognitive behavioural therapy (CBT) alone may be beneficial in treating patients with dissociative (non-epileptic) seizures. A randomised controlled trial of patients who undertook 12 sessions of CBT which taught patients how to interrupt warning signs before seizure onset, challenged unhelpful thoughts and helped patients start activities they had been avoiding found a reduction in the seizure frequency with positive outcomes sustained at six month follow up. A large multicentre trial of CBT for dissociative (non-epileptic) seizures started in 2015 in the UK.

For many patients with FND, accessing treatment can be difficult. Availability of expertise is limited and they may feel that they are being dismissed or told 'it's all in your head' especially if psychological input is part of the treatment plan. Some medical professionals are uncomfortable explaining and treating patients with functional symptoms. Changes in the diagnostic criteria, increasing evidence, literature about how to make the diagnosis and how to explain it and changes in medical training is slowly changing this

After a diagnosis of functional neurological disorder has been made, it is important that the neurologist explains the illness fully to the patient to ensure the patient understands the diagnosis.

Some, but not all patients with FND may experience low moods or anxiety due to their condition. However, they will often not seek treatment due being worried that a doctor will blame their symptoms on their anxiety or depression.

It is recommended that the treatment of functional neurological disorder should be balanced and involve a whole-person approach. This means that it should include professionals from multiple departments, including neurologists, general practitioners (or primary health care providers), physiotherapists, occupational therapists. At the same time, ruling out secondary gain, malingering, conversion disorder and other factors, including the time and financial resources involved in assessing and treating patients who demand hospital resources but would be better served in psychological settings, must all be balanced.

In the case of pathological gambling, along with fluvoxamine, clomipramine has been shown effective in the treatment, with reducing the problems of pathological gambling in a subject by up to 90%. Whereas in trichotillomania, the use of clomipramine has again been found to be effective, fluoxetine has not produced consistent positive results. Fluoxetine, however, has produced positive results in the treatment of pathological skin picking disorder, although more research is needed to conclude this information. Fluoxetine has also been evaluated in treating IED and demonstrated significant improvement in reducing frequency and severity of impulsive aggression and irritability in a sample of 100 subjects who were randomized into a 14-week, double-blind study. Despite a large decrease in impulsive aggression behavior from baseline, only 44% of fluoxetine responders and 29% of all fluoxetine subjects were considered to be in full remission at the end of the study. Paroxetine has shown to be somewhat effective although the results are inconsistent. Another medication, escitalopram, has shown to improve the condition of the subjects of pathological gambling with anxiety symptoms. The results suggest that although SSRIs have shown positive results in the treatment of pathological gambling, inconsistent results with the use of SSRIs have been obtained which might suggest a neurological heterogeneity in the impulse-control disorder spectrum.