Encyclopedia of Psychology and Law

Finally, there is some evidence that auditory halluci-

nations may be related to tissue loss in the primary

auditory cortex. The receptors in the auditory cortex

process information and then send it to the thalamus,

which filters the information before sending it to be

decoded in the brain. These complex processes trans-

form abstract sensory information such as sound and

light waves into recognizable images and voices of the

world around us. While dysfunctions in any of these

structures alone would not explain the presence of hal-

lucinations, it is possible that patients with schizophre-

nia may experience the malfunction of several of these

neurotransmitter and receptors networks simultane-

ously. None of these defects alone would cause schizo-

phrenia or trigger a psychotic episode; however, they

do confer a predisposition for developing schizophre-

nia. Thus, individuals with these defects would be more

likely to experience auditory or visual misperceptions,

which would present themselves as auditory or visual

hallucinations.

Hallucinations and Posttraumatic

Stress Disorder

Trauma survivors who develop PTSD often report

visual and auditory hallucinations. Hallucinations in

trauma survivors are often referred to as flashbacks.

During these flashbacks, the person relives the trau-

matic experience as if they were really there. Although

these flashbacks can be described as hallucinations,

they are nonpsychotic in nature. It is believed that flash-

backs in patients with PTSD occur following abnormal

memory formation patterns that occur during the trau-

matic experience. In cases of trauma, it is hypothesized

that instead of being processed in the hippocampus,

where memories are described using language, trau-

matic memories are stored in the amygdala, which

stores the memory as an emotional experience. As a

consequence, the traumatic memories are stored in the

amygdala without words but only with intense emo-

tions, and the memories are associated with vivid sen-

sations and sensory perceptions that can manifest

themselves as hallucinations during stressful situations.

Hallucinations and Substance Abuse

Hallucinations can be caused by overdoses of prescrip-

tion drugs, illegal drugs, and alcohol or drug with-

drawal. Substance-induced hallucinations seem to

occur because of blocking of the action of serotonin,

while phencyclidine induces hallucinations by block-

ing glutamate receptors. Interestingly, individuals who

have used lysergic acid diethylamide (LSD) have

reported flashbacks, or spontaneous hallucinations,

which occur when the person is no longer taking the

drug. This phenomenon is referred to as hallucinogen

persisting perception disorder.

Withdrawal from alcohol can also result in halluci-

nations. These types of hallucinations usually occur if a

chronic alcoholic suddenly stops drinking alcohol.

Initially, on withdrawal, patients report auditory hallu-

cinations, such as hearing threatening or accusatory

voices. After several days of withdrawal, patients can

experience delirium tremens, a condition in which they

feel disoriented, depressed, and feverish and experience

visual hallucinations.

Hallucinations and Mood Disorder

Hallucinations have also been associated with mood

disorders. Approximately 20% of patients in the manic

phase of bipolar disorder and almost 10% of patients

with major depressive disorder experience auditory

hallucinations. It is not clear what causes patients with

mood disorders to experience hallucinations. There

appears to be a genetic link, as psychotic mood states

have been found to run in families. Additionally, ele-

vated levels of the hormone cortisol have been found

in patients who experience depression with psychosis.

Assessment of Hallucinations

To assess hallucinations, the general physician, psychi-

atrist, or psychologist should conduct a thorough med-

ical and psychosocial examination to rule out possible

organic, environmental, or psychological causes.

Depending on the patient’s symptoms and medical his-

tory, such an evaluation may also involve laboratory

tests and imaging studies. If a psychological cause

such as schizophrenia is suspected, a psychologist will

typically conduct an interview with the patient and his

or her family and administer one of several clinical

inventories, or tests, to evaluate the mental status of the

patient. This could include the Mini-Mental Status

Exam (MMSE), the Psychotic Symptom Rating Scales,

the Positive and Negative Syndrome Scale, or the

Scale for Assessment of Positive Symptoms. A total

score of 20 or lower on the MMSE is generally indica-

tive of delirium, dementia, schizophrenia, or severe

depression.

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