Many different causes of aboulia have been suggested. While there is some debate about the validity of aboulia as a separate disease, experts mostly agree that aboulia is the result of frontal lesions and not with cerebellar or brainstem lesions. As a result of more and more evidence showing that the mesolimbic and the mesocortical dopamine system are key to motivation and responsiveness to reward, aboulia may be a dopamine-related dysfunction. Aboulia may also result from a variety of brain injuries which cause personality change, such as dementing illnesses, trauma, or intracerebral hemorrhage (stroke), especially stroke causing diffuse injury to the right hemisphere.

Injuries to the frontal lobe and/or the basal ganglia can interfere with an individual's ability to initiate speech, movement, and social interaction. Studies have shown that 5-67% of all patients with traumatic brain injuries and 13% of patients with lesions on their basal ganglia suffer from some form of diminished motivation.

Aboulia has also been associated with amphetamine withdrawal. It may complicate rehabilitation when a stroke patient is uninterested in performing tasks like walking despite being capable of doing so. It should be differentiated from apraxia, when a brain injured patient has impairment in comprehending the movements necessary to perform a motor task despite not having any paralysis that prevents performing the task; that condition can also result in lack of initiation of activity.

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.

People with avolition often want to complete certain tasks but lack the ability to initiate behaviours necessary to complete them. Avolition is most commonly seen as a symptom of some other disorder, but might be considered a primary clinical disturbance of itself (or as a coexisting second disorder) related to disorders of diminished motivation. In 2006, avolition was identified as a negative symptom of schizophrenia by the National Institute of Mental Health (NIMH), and has been observed in patients with bipolar disorder as well as resulting from trauma.

Avolition is sometimes mistaken for other, similar symptoms also affecting motivation, such as aboulia, anhedonia and asociality, or strong general disinterest. For example, aboulia is also a restriction in motivation and initiation, but characterized by an inability to set goals or make decisions and considered a disorder of diminished motivation. In order to provide effective treatment, the underlying cause of avolition (if any) has to be identified and it is important to properly differentiate it from other symptoms, even though they might reflect similar aspects of mental illness.

There is no known single cause or causes of schizophrenia, however, it is a heritable disorder.

Several environmental factors, including perinatal complications and prenatal maternal infections could cause schizophrenia. These factors in a greater severity or frequency could result in an earlier onset of schizophrenia. Maybe a genetic predisposition is a important factor too, familial illness reported for childhood-onset schizophrenic patients.

Schizophrenia disorders in children are rare. Boys are twice as likely to be diagnosed with childhood schizophrenia. There is often an disproportionately large number of males with childhood schizophrenia, because the age of onset of the disorder is earlier in males than females by about 5 years. People have been and still are reluctant to diagnose schizophrenia early on, primarily due to the stigma attached to it.

While very early-onset schizophrenia is a rare event, with prevalence of about 1:10,000, early-onset schizophrenia is manifests more often with an estimated prevalence of 0.5 %.

Allochiria (from the Greek meaning "other hand") is a neurological disorder in which the patient responds to stimuli presented to one side of their body as if the stimuli had been presented at the opposite side. It is associated with spatial s, usually symmetrical, of stimuli from one side of the body (or of the space) to the opposite one. Thus a touch to the left side of the body will be reported as a touch to the right side, which is also known as somatosensory allochiria. If the auditory or visual senses are affected, sounds (a person's voice for instance) will be reported as being heard on the opposite side to that on which they occur and objects presented visually will be reported as having been presented on the opposite side. Often patients may express allochiria in their drawing while copying an image. Allochiria often co-occurs with unilateral neglect and, like hemispatial neglect, the disorder arises commonly from damage to the right parietal lobe.

Allochiria is often confused with alloesthesia, also known as false allochiria. True allochiria is a symptom of dyschiria and unilateral neglect. Dyschiria is a disorder in the localization of sensation due to various degrees of dissociation and cause impairment in one side causing the inability to tell which side of the body was touched.

Dysprosody, which may manifest as pseudo-foreign accent syndrome, refers to a disorder in which one or more of the prosodic functions are either compromised or eliminated completely.

Prosody refers to the variations in melody, intonation, pauses, stresses, intensity, vocal quality, and accents of speech. As a result, prosody has a wide array of functions, including expression on linguistic, attitudinal, pragmatic, affective and personal levels of speech. People diagnosed with dysprosody most commonly experience difficulties in pitch or timing control. Essentially, people diagnosed with the disease can comprehend language and vocalize what they intend to say, however, they are not able to control the way in which the words come out of their mouths. Since dysprosody is the rarest neurological speech disorder discovered, not much is conclusively known or understood about the disorder. The most obvious expression of dysprosody is when a person starts speaking in an accent which is not their own. Speaking in a foreign accent is only one type of dysprosody, as the disease can also manifest itself in other ways, such as changes in pitch, volume, and rhythm of speech. It is still very unclear as to how damage to the brain causes the disruption of prosodic function. The only form of effective treatment developed for dysprosody is speech therapy.

Dysprosody is usually attributed to neurological damage, such as brain tumors, brain trauma, brain vascular damage, stroke and severe head injury. To better understand the causes of the disease, 25 cases of dysprosody diagnosed between 1907-1978 were examined more closely. It was found that the majority developed dysprosody after a cerebrovascular accident, while another 6 cases developed after a head trauma. In that same study, 16 of the patients were female, while 9 were male. However, there has been no conclusive evidence that gender affects the onset of dysprosody. There has been no evidence that ethnicity, age, or genetics has any impact on the development of dysprosody.

In another reported case in 2004, a patient presented with dysprosody under interesting circumstances. The patient underwent surgery to correct a Reinke's edema, which originates in the vocal folds of the larynx. After the surgery, however, she began speaking in a foreign German accent. Neurological examinations were carried out on the patient through magnetic resonance imaging, but the results were completely normal. The only conclusion the doctors could make was that the surgery somehow changed the patient's vocal identification causing the new voice pattern. It was possible that the patient suffered a lack of oxygen to the brain during the surgery, which would have gone undetected by the resonance imaging, causing dysprosody. Although most causes of dysprosody are due to neurological damage, this case study shows that there can be other causes which are not necessarily neurologically based.

Allochiria has been observed mainly in the context of neglect which is usually due to a lesion that affects the right parietal lobe. In patients with allochiria, their sensibility is retained completely but the patient is not clear as to which side of the body has been touched. Their power of localization is retained but error exists to the side touched and they often refer the irritation to the corresponding part of the limb. In the patients' mind there is doubt or error as to which side of the body is touched.

There are multiple definitions of allochiria. According to Musser, allochiria is the reference of a sensory stimulus to the corresponding location on the opposite location on the opposite side of the body. Judson Bury says that a patient may refer to an impression on one side to a corresponding place on the opposite side of the body. Thus, if a patient is pricked on one limb, he may say that he feels it on the other. Overall, even though different author's definition differs on points such as the type of stimulus, and the symmetry between the site of the stimulus and the seat of its localization, they all agree that an essential feature of allochiria is the deflection of a sensation to the wrong side of the body, which is true allochiria. In none of these definitions is any stress laid on the state of the patient's knowledge of a right or left side and the symptoms are seen as an error in localization.

Obsersteiner laid stress that there is in allochiria no defect in vertical localization but merely confusion in the patient's mind between the opposite sides of the body and come to look upon the symptom as simply any form of bad mistake in localization.

There is in the patient's mind doubt or error as to the side touched while sensibility including the power of localization is otherwise retained. Allochiria has been described as occurring in nerve lesions, Hemiplegia, disseminated sclerosis Multiple sclerosis, tabes dorsalis, unilateral injury to the spinal cord, Ménière's disease, hysteria, symmetrical gangrene, and in connection with touch, pain, the "muscle sense," the temperature sense, sight, smell, taste, hearing, and the electrical reactions.

Allochiria can occur in relation to any or every segment of the body. In some cases allochiria may be , and in others it may be restricted to certain regions of the body, or even only to one part of the body. Allochiria is marked to have connections with a variety of senses and sometimes only certain kinds of stimuli can arouse the appropriate feeling of one sidedness.

Pick's disease is a term that can be used in two different ways. It has traditionally been used as a term for a group of neurodegenerative diseases with symptoms attributable to frontal and temporal lobe dysfunction. Common symptoms that are noticed early are personality and emotional changes, as well as deterioration of language. This condition is now more commonly called frontotemporal dementia by professionals, and the use of "Pick's disease" as a clinical diagnosis has fallen out of fashion. The second use of the term (and the one now used among professionals) is to mean a specific pathology that is one of the causes of frontotemporal lobar degeneration. These two uses have previously led to confusion among professionals and patients and so its use should be restricted to the specific pathological subtype described below. It is also known as Pick disease and PiD (not to be confused with pelvic inflammatory disease (PID) or Parkinson's disease (PD)). A defining characteristic of the disease is build-up of tau proteins in neurons, accumulating into silver-staining, spherical aggregations known as "Pick bodies".

The symptoms of Pick's disease include difficulty in language and thinking, efforts to dissociate from family, behavioral changes, unwarranted anxiety, irrational fears, CBD (Compulsive buying disorder, or oniomania), impaired regulation of social conduct (e.g., breaches of etiquette, vulgar language, tactlessness, , misperception), passivity, low motivation (aboulia), inertia, over-activity, pacing and wandering. It is a characteristic of Pick’s disease that dysfunctional, argumentative, or hostile social conduct is initially exhibited towards family members and not initially exhibited in a workplace or neutral environment. The changes in personality allow doctors to distinguish between Pick's disease and Alzheimer's disease. Pick's disease is one of the causes of the clinical syndrome of frontotemporal lobar degeneration which has three subtypes. Pick's disease pathology is associated more with the frontotemporal dementia and progressive nonfluent aphasia subtypes than the semantic dementia subtype.