Hallucinations are false or distorted sensory experiences that appear to be veridical perceptions. These sensory impressions are generated by the mind rather than by any external stimuli, and may be seen, heard, felt, and even smelled or tasted.
A delusion is a false belief based on incorrect inference about external reality that is firmly sustained despite what almost everybody else believes and despite what constitutes incontrovertible and obvious proof or evidence to the contrary. The belief is not one ordinarily accepted by other members of the person's culture or subculture (e.g., it is not an article of religious faith).
A hallucination occurs when environmental, emotional, or physical factors such as stress, medication, extreme fatigue, or mental illness cause the mechanism within the brain that helps to distinguish conscious perceptions from internal, memory-based perceptions to misfire. As a result, hallucinations occur during periods of consciousness. They can appear in the form of visions, voices or sounds, tactile feelings (known as haptic hallucinations), smells, or tastes.
Delusions are a common symptom of several mood and personality-related mental illnesses, including schizoaffective disorder, schizophrenia, shared psychotic disorder, major depressive disorder, and bipolar disorder. They are also the major feature of delusional disorder. Individuals with delusional disorder suffer from long-term, complex delusions that fall into one of six categories: persecutory, grandiose, jealousy, erotomanic, somatic, or mixed.
Delusions are erroneous beliefs and hallucinations are perceptions of stimuli that don't actually exist. For example, a delusion may be a belief that the government is controlled by reptilian men who are poisoning the water supply to enslave the masses. A hallucination may be hearing "voices" or seeing ghosts.
It is common for many people to hold a shared delusion that stems from their paranoia or belief system. People in cults may all believe that their leader is a messiah or that the end of the world is nigh. In fact, some atheists believe that all organized religion and faith in God is a delusion. In contrast, it is quite rare for two people to share a hallucination.
- Somatic/tactile hallucination
- Visual hallucination
- Mood-congruent hallucination
- Mood-incongruent hallucination
- Delusion of control
- Delusional jealousy (or delusion of infidelity)
- Delusion of guilt or sin (or delusion of self-accusation)
- Delusion of reference
- Grandiose delusion
- Religious delusion
- Somatic delusion
- Psychotic disorders:
- includes schizophrenia, schizoaffective disorder, schizophreniform disorder, shared psychotic disorder, brief psychotic disorder, substance-induced psychotic disorder, bipolar disorder, major depression with psychotic features, delirium, or dementia. Auditory hallucinations, in particular, are common in psychotic disorders such as schizophrenia.
- Use of certain recreational drugs may induce hallucinations, including amphetamines and cocaine, hallucinogens (such as lysergic acid diethylamide or LSD), phencyclidine (PCP), and cannabis or marijuana.
- Withdrawal from some recreational drugs can produce hallucinations, including withdrawal from alcohol, sedatives, hypnotics, or anxiolytics.
- Stress. Prolonged or extreme stress can impede thought processes and trigger hallucinations.
- Sleep deprivation and/or exhaustion. Physical and emotional exhaustion can induce hallucinations by blurring the line between sleep and wakefulness.
- Meditation and/or sensory deprivation. When the brain lacks external stimulation to form perceptions, it may compensate by referencing the memory and form hallucinatory perceptions. This condition is commonly found in blind and deaf individuals.
- Electrical or neurochemical activity in the brain. A hallucinatory sensation-usually involving touch-called an aura, often appears before, and gives warning of, a migraine. Also, auras involving smell and touch (tactile) are known to warn of the onset of an epileptic attack.
- Brain damage or disease. Lesions or injuries to the brain may alter brain function and produce hallucinations.
Delusions may be present in any of the following mental disorders:
- psychotic disorders, or disorders in which the affected person has a diminished or distorted sense of reality and cannot distinguish the real from the unreal, including schizophrenia, schizoaffective disorder, delusional disorder, schizophreniform disorder, shared psychotic disorder, brief psychotic disorder, and substance-induced psychotic disorder
- bipolar disorder
- major depressive disorder with psychotic features
- Overvalued ideas may be present in anorexia nervosa, obsessive-compulsive disorder, body dysmorphic disorder, or hypochondriasis.
In many cases, chronic hallucinations caused by schizophrenia or some other mental illness can be controlled by medication. If hallucinations persist, psychosocial therapy can be helpful in teaching the patient the coping skills to deal with them. Hallucinations due to sleep deprivation or extreme stress generally stop after the cause is removed.
Delusional disorder is typically a chronic condition, but with appropriate treatment, a remission of delusional symptoms occurs in up to 50% of patients. However, because of their strong belief in the reality of their delusions and a lack of insight into their condition, individuals with this disorder may never seek treatment, or may be resistant to exploring their condition in psychotherapy.
Work up and diagnosis
- History and physical examination
- In caring for patients with major psychiatric illness, follow three important principles: Know the patient's drug regimen, work with psychiatrist if changes are needed, and remember that chronic psychiatric patients have difficulty communicating medical history and needs
- Diagnosis of schizophrenia requires two positive or negative symptoms present for 1 month and signs continuing for at least 6 months (DSM-IV criteria)
- Assess for suicidal/homicidal ideations
- Note timing of hallucinations (e.g., following alcohol or drug use, at random, under stress)
Initial labs may include electrolytes, glucose, calcium, BUN/creatinine, albumin, liver function tests, alkaline phosphatase, magnesium, phosphate, CBC, ECG, pulse oximetry, urinalysis, toxicology screen, and drug levels
Chest X-ray may be indicated for infectious etiologies of delirium; lumbar puncture may be indicated
- Further tests, if delirium is suspected, include vitamin B12 and folate levels, ANA, ammonia, and heavy metal screen
- EEG may reveal slowing activity in delirium, low-voltage fast activity in alcohol withdrawal. A psychiatric consult after medical causes of psychosis are ruled out.
The examiner bases the diagnosis of delusion on the following criteria set forth in the Diagnostic and Statistical manual of Mental Disorders, 4th edition-text revision:
- Nonbizarre delusions of at least 1 month's duration are present, involving real life situations, such as being followed, poisoned, infected, loved at a distance or deceived by one’s lover.
- The patient’s symptoms have never met the criteria known as characteristic symptoms of schizophrenia.However, tactile and auditory hallucinations may be present if they are related to delusional theme.
- Apart from being affected by the delusions or its ramifications, the patient isn’t markedly impaired functionally nor is his behavior odd or bizarre.
- If mood disturbances have occurred concurrently with delusions, their total duration has been brief relative to the duration of the delusional disturbance.
- The disturbance doesn’t result from the direct physiologic effects of a substance or a general medical condition.
Treat hallucinations symptomatically with antipsychotic drugs (e.g., haloperidol, risperidone, olanzapine)
- Combination of drug therapy and psychotherapy.
- Drug treatment with antipsychotic agents,antidepressants and anxiolytics may be prescribed