Differentiating organic from functional psychosis

Differentiating organic from functional psychosis

Steven C. Dilsaver

Psychosis should be the concern of physicians in all clinical specialties. First, psychosis can be associated with diseases of every organ system and therefore may be a sign of an illness requiring medical rather than psychiatric treatment. Second, psychosis can be induced by pharmacologic treatments used in almost every area of medicine. It can also be caused by substances of abuse or by the withdrawal of a variety of drugs. Third, patients with psychosis of ten have concerns about their health and are likely to seek help from a family physician or an internist. Finally, individuals with psychiatric illnesses have the same health-care needs as the rest of the population and thus require the services of nonpsychiatrists. Consequently, an understanding of the nature of psychosis and a knowledge of its causes and treatment are fundamental to the practice of medicine.


Psychosis is characterized by an adherence to fixed, false beliefs outside the normal range for a person’s subculture, by a hallucinatory experience that is not recognized as such or by a formally defined disorder of thought.(1-3)

False beliefs that cause a person to suffer, that produce conflict with others or that render a person unable to comfortably adapt to the demands of life are delusions if they are not relinquished when the person is presented with adequate evidence to the contrary. This definition allows for idiosyncrasy and for differences in the beliefs of a person’s subculture from those of the majority of the population.

Organic vs. Functional Psychoses

Psychoses may be classified as organic or functional.(1-3) In organic psychoses, structural or physiologic dysfunction directly or indirectly affecting the brain is known to cause the psychosis.(3,4) In functional psychosis, behavior or experience is altered, but the cause of the pathologic state is not yet identifiable.

Distinguishing organic from functional psychoses is essential. If the cause of psychosis is not recognized quickly, a patient may die because a potentially effective treatment is not given. For example, delirium, which is of ten accompanied by hallucinations and delusions, may be caused by a severe infection that is responsive to antibiotics. Affective vs. Nonaffective Psychoses

Psychosis is a syndrome, and the predominant characteristics of the syndrome are used in determining its classification. The two major classes of psychosis are termed “affective” and “nonaffective.” Both classes include organic and functional disorders.

Affective psychoses are characterized by prominent disturbance of mood. Examples of the affective psychoses are major depression and mania with psychotic features. In contrast, schizophrenia is a nonaffective psychosis. Patients with schizophrenia may experience depression, but mood disturbance is not a core element in the clinical course of their illness.(1-3) Prescription agents and drugs of abuse may cause either affective or nonaffective psychoses. (5,6)

It may be very difficult to distinguish an affective psychosis from a nonaffective psychosis based on the signs and symptoms at the time of presentation. For example, schizophreniform disorder is a functional psychosis characterized by delusions, hallucinations, confusion and disorganization of thought processes for a period of less than six months.(3) It may be very difficult, if not impossible, for astute clinicians to confidently distinguish schizophreniform disorder from mania based on the clinical features observed at the time of presentation.(7-9)

Knowledge of the course of the illness, the family history and the patient’s previous response to treatment may be critical factors in determining treatment. For example, a manic episode is more likely in a patient who has in the past exhibited signs of mania (e.g., euphoric or irritable mood, pressured speech, flight of ideas, heightened level of energy, decreased need for sleep, indefatigability, increased involvement in goal-directed activity, increased self-esteem or delusions of grandeur), has a family history of affective illness or has a history of good response to lithium carbonate (Eskalith, Lithane, Lithobid), carbamazepine (Tegretol) or valproic acid (Depakene).


Certain types of delusions are characteristic of psychosis in the context of affective illness. These are referred to as mood-congruent delusions(l-3)(Table 1). A person’s belief that he or she has committed an egregious act for which condemnation to hell is deserved, even though his or her religious beliefs do not support this conclusion, is a typical mood-congruent delusion. This is a delusion of guilt. Since the time of Hippocrates, irrational feelings of guilt have been recognized as characteristic of depressive illness. Guilt is included among the many items on standardized instruments used to quantify the severity of depression, such as the rating scales developed by Carroll and associates(10) and by Hamilton.

A person’s belief that his or her thoughts are controlled by an external force is a classic example of a mood-incongruent delusion. Although patients with affective psychosis sometimes have mood-incongruent delusions, delusions of this type are much more common in nonaffective psychoses.


Hallucinations are auditory, visual, tactile, olfactory or gustatory experiences that occur in the absence of a stimulus. While nonauditory hallucinations are more characteristic of organic psychoses, they may also occur in functional psychoses (Table 2).

The occurrence of a hallucination does not necessarily indicate that a person is psychotic. For example, a person with a migraine headache may have a visual hallucination, but if the person recognizes that the hallucination is the product of a neurologic disorder, he or she is not psychotic. A person who is psychotic fails to appreciate that a perception occurs despite the absence of an adequate stimulus. Hallucinations must be distinguished from illusions. An illusion is a perception that occurs in response to a stimulus, but the person reaches an erroneous conclusion about the cause of the perception. For example, a person may glance at windruffled foliage and perceive a deer running through the forest. Although illusions are normal experiences, they may occur with a high degree of frequency in some psychotic individuals. Illusions are particularly common in patients with dementia and delirium.

Thought Disorders

Distinct patterns of cognitive impairment occur in organic and functional psychoses. The technical phrase for this type of cognitive impairment is formal thought disorder.”

Characteristics of this type of disorder include speech that cannot be understood because of inadequate connections between words (“word salad”) or phrases and sentences (loose associations); the use of illogical meaningless language; the creation of useless novel terms neologisms); the failure to complete sentences or phrases (thought blocking); the intrusion of irrelevancies into conversation; abrupt changes in subject matter; distorted grammar or syntax; the idiosyncratic use of words, or the use of empty, stereotyped or obscure phrases(1,2) (Table 3).

Formal thought disorder is an autonomous, independent attribute of psychosis. By definition, it cannot be caused by extreme psychomotor retardation (which can create the appearance of thought blocking), hallucinations or delusions. Treatment of Functional Psychoses

It is critical to make a preliminary decision about whether a patient has an affective or nonaffective psychosis, since the type of psychosis determines the pharmacologic agents to be used.(15,16) Many patients with affective psychoses can be treated without antipsychotic agents.

Antipsychotic agents are a class of drugs that block dopamine receptors. They are often referred to as neuroleptics because of their tendency to produce catalepsy. Antipsychotic agents are aversive: they act on networks in the brain, mediating the experience of pleasure. (17) Antidopaminergic drugs decrease drive-reduction behavior in animals.(18,19) This is exhibited by substantial decrements in positively reinfor-ced behavior such as the self-administration of cocaine and amphetamine, self-induced electrical stimulation of a region that, in the absence of dopamine receptor blockade, produces pleasure,(19) and the work expended to obtain food and water. (A review of this subject can be found in an article by Ettenberg.(21))

Antipsychotic agents carry a high risk of annoying and sometimes frightening side effects, such as parkinsonism, (22) dystonia and akathisia. Akathisia, which is characterized by a subjective sense of restlessness and a strong drive to continually move, can be refractory to treatment. Tardive dyskinesia, a long-term adverse effect of antipsychotics, is an irreversible hyperkinetic disorder of movement involving the lips, the tongue, and the facial and orbicular musculature.(25) Dystonia of multiple muscle groups, dysphagia and impairment of the synchronous function of intercostal muscles sometimes occur. Patients with mood disorders are thought to be at particularly high risk for tardive dyskinesia.

Schizophrenia is the prototype of a nonaffective psychosis. Antipsychotic agents are the treatment of choice for this disorder. Depression with psychotic features is frequently treated with the combination of an antidepressant and an antipsychotic. Mania with psychosis often responds to lithium carbonate,(26) carbamazepine(27) or valproic acid.(28) These drugs are not included in the class formally referred to as antipsychotic agents, but they do have antipsychotic properties. They also decrease the frequency of the recurrence of manic and depressive episodes in patients with bipolar disorder.

Dopamine receptor antagonists do not have appreciable value as prophylactic agents in patients with mood disorders. However, continued treatment with antipsychotics does decrease the probability of the recurrence of psychosis in patients with schizophrenia.

Organic Mental Disorders

Many nonpsychiatric disorders or their treatments can produce psychosis. Such disorders are termed “organic mental disorders.”(3) Organic mental disorders include psychotic and nonpsychotic disorders, as well as affective and nonaffective psychoses. The organic mental disorders associated with prominent disturbance of mood are labeled “organic mood disorders.” Reserpine (Serpalan, Serpasil) and methyldopa (Aldomet) are examples of drugs that can produce an organic mood disorder with psychotic features.

Delirium, one of the organic mental disorders, is a disorder of mentation marked by clouding of consciousness (level of alertness), inattention, and impairment of memory and other cognitive abilities.(30) Delirium is often associated with agitation, incoherence, illusions or hallucinations. Paranoia may be prominent. Delirium is always regarded as an emergency, because it is often associated with drug intoxications or with certain diseases, any of which may be fatal if not rapidly treated. Lithium toxicity may, for example, initially manifest as delirium, followed by coma, cardiovascular collapse and death in the absence of proper care.

Diseases that produce organic mental disorder with psychotic features are listed in Table 4.(31-39) Commonly used drugs that can produce psychosis are listed in Table 5.(36,37,39)

Evaluation of Patients with Psychosis

Organic etiologies should always be suspected when a patient presents with psychosis. Clues to nonpsychiatric causes of psychosis include the following: the onset of the first episode of psychosis after age 40; the absence of a family history of a functional disorder associated with psychosis; the presence of systemic disease; the occurrence of delirium; the treatment of systemic disease with centrally acting drugs; a temporal association of psychosis with the withdrawal of a drug; substance abuse; any evidence of increased intracranial pressure; the patient’s report of nonauditory hallucinations; the occurrence of autonomic dysfunction (hypertension, hypotension, hyperpyrexia, tachycardia, bradycardia, tachypnea or shallow, decreased rate of respiration), and a history of good premorbid function.

Evaluation of psychotic patients is designed to identify the presence of drugs, physiologic dysfunction or anatomic lesions that are likely to produce psychosis. The evaluation includes a physical and neurologic examination and laboratory screening tests selected in part on the basis of the presentation and initial findings. Components of the routine evaluation of psychotic patients and contingencies for ordering specific procedures are listed in Table 6.


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