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Hallucinations Vs Delusions: Differences Worth Knowing!

“Hallucination and Delusion” are two terms which may look similar to a layman, but in real they are pretty different from each other. We will know about the most crucial differences between Hallucinations and Delusions in this current article of ours.

Basic Differences Between Hallucinations and Delusions

Basic Differences Between Hallucinations and Delusions:

Hallucinations are the false or distorted sensory experiences generated by the mind rather than by any external stimuli and they appear to be veridical perceptions. These sensory experiences may be seen, felt, heard and even smelt or tasted. Hallucinations may be experienced when environmental, emotional or physical factors like stress, medication, excessive fatigue or any mental illness cause the mechanism inside the person’s brain that aids to distinguish conscious perceptions from internal, memory-based perceptions to misfire. So, it is obvious that hallucinations mostly occur during periods of consciousness.

However, Delusions are a false belief that is based on incorrect inference about external reality or the false belief that is fanciful and derived from deception. Delusions are mostly the common symptoms of certain mood and personality related mental illnesses like Schizoaffective disorder, shared psychotic disorder, schizophrenia, major depressive disorder and Bipolar disorder. They may also be symptoms of delusional disorder.

Difference Between Hallucinations and Delusions Based on Epidemiology

It is estimated that many people, i.e. about 4% experience hallucinations unrelated to mental illness. It is also estimated in a survey that the olfactory and gustatory types of hallucinations are the most common of all types of hallucinations. Also survey tells that Auditory hallucinations are commonly experienced in adolescent psychosis.

An American study of the general population reported that people with low self-esteem are more prone to develop delusions. It is found from a UK study that 39% of 1000 randomly selected people (who completed the Cardiff belief questionnaire) were reported having at least one strong delusional like belief.

Difference Between Hallucinations and Delusions Based on Symptoms

Difference Between Hallucinations and Delusions Based on Symptoms/Behaviour of the Victim

In Hallucination, the person who is affected will insist that they see things, smell or hear things that may or may not exist in real. They can also constantly look around and seem scared.

In case of delusion, the affected person may be short-tempered or aggressive. In such case, he or she may also attack you or objects believing that they may cause them harm. Such people suffering from delusions may believe certain things that are untrue. It is seen that their behaviour will change depending on the type of delusion they have.

Difference Between Hallucinations Vs Delusions Based on Causes

Various causes that can lead to Hallucination include the following:

  • Psychotic disorders like Schizophrenia, shared psychotic disorder, schizoaffective disorder, bipolar disorder, major depression with psychotic features, dementia etc may cause hallucinations.
  • Prolonged or extreme stress can impede thought processes and cause or trigger hallucinations.
  • Certain recreational drugs like cocaine and amphetamines, cannabis or marijuana, phencyclidine(PCP) etc can cause hallucinations.
  • Withdrawal from some recreational drugs, including withdrawal from sedatives, alcohol, hypnotics etc can also produce hallucinations.
  • Lack of sleep or exhaustion can also cause hallucination.
  • Brain damage or brain diseases can lead to hallucinations. Lesions or injuries to the brain can lead to an alteration in brain function and cause hallucinations.
  • Meditation and sensory deprivation may also cause hallucinations. Mostly blind and deaf individuals meet with this condition of hallucinations. Actually when the brain lacks an external stimulation to form perceptions, it may compensate by referencing the memory and form perceptions based on hallucinations.

Delusions may have the following causes:

  • Patients with mental disorders like psychotic disorders, schizophrenia, shared psychotic disorder, brief psychotic disorder, schizoaffective disorder, delusional disorder etc may suffer from delusions.
  • Apart from this, Bipolar disorder, dementia, major depression with psychotic features etc may also cause delusion in a person
  • Overvalued ideas may be present in anorexia nervosa, body dysmorphic disorder, Obsessive compulsive disorder etc.

Differences Between Hallucinations and Delusions Based on Types

Based on the types, we can differentiate between Hallucinations and Delusions as follows:

Different types of hallucinations include the following:

  1. Auditory hallucination
  2. Olfactory hallucination
  3. Gustatory hallucination
  4. Visual hallucination
  5. Somatic/tactile hallucination
  6. Mood-congruent hallucination
  7. Mood-incongruent hallucination

Different types of delusion include the following:

  1. Delusion of control
  2. Delusion of guilt or sin
  3. Delusional jealousy
  4. Religious delusion
  5. Grandiose delusion
  6. Delusion of reference
  7. Somatic delusion

Differences Between Hallucinations and Delusions Based on Diagnosis Procedures

Diagnosis of Hallucinations in a patient may require the patient’s medical history and some physical examinations done by the doctor.

  • Schizophrenic patients may encounter hallucinations. Diagnosis of patients with schizophrenia requires two positive or negative symptoms to be present for one month and signs continuing for at least 6 months of period.
  • Diagnosis also include assess for suicidal or homicidal ideations
  • The diagnosis steps also include noting the timing of hallucination(For, example; following alcohol or certain drug use, at random timing, or under stress etc)
  • There may be a requirement of some lab tests to diagnose hallucination in a patient. Initial lab tests may include electrolytes, calcium, glucose, liver function tests, creatinine, albumin, alkaline phosphate, phosphate, magnesium, CBC, ECG, urinalysis, toxicology screen, pulse oximetry, and drug levels Chest X-ray may be indicated for infectious etiologies of delirium; etc
  • There may be requirement of further tests like Vitamin B12 and folate levels, ANA, Ammonia and heavy metal screen etc in case delirium is suspected
  • EEG may be helpful in revealing slowing activity in delirium, low-voltage fast activity in alcohol withdrawal etc.
  • Once the medical causes of psychosis, leading to hallucination are ruled out; a psychiatric consult may be essential for treatments to begin.

Diagnosis for delusions may be based on the following criteria

  • Non-bizarre delusions for at least one month are present, which involve real life situations like being followed, poisoned, 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, there may be presence of tactile or auditory hallucinations in case they are related to delusional theme.
  • Apart from being affected by the delusions, the patient is not markedly impaired functionally nor is his or her behaviour bizarre or odd.
  • If mood disturbances have taken place concurrently with delusions; their total duration has been brief in relation with the duration of the delusional disturbance.
  • The disturbance doesn’t result from the direct physiologic effects of a substance or a general medical condition.

Difference Between Hallucinations and Delusions Based on their Treatment

Coming to the differences between the treatment procedures for Hallucinations and delusions; hallucinations are usually treated symptomatically by antipsychotic drugs like risperidone, laoperidol, olanzapine etc. However, treating delusions require a combination of drug therapy as well as psychotherapy. In case of delusion, drug treatment with antipsychotic agents, antidepressants and anxiolytics may be prescribed by the doctor.

Differences Between Hallucinations and Delusions Based on Prognosis

In many cases; chronic hallucinations caused by mental illness like schizophrenia or any other mental illness can be controlled by medication. It is also noted that in cases where medication do not work for treating symptoms of hallucination, psychosocial therapy can be helpful as it teaches the patient the coping skills so as to deal with them. It is found that hallucinations caused due to deprivation in sleep or because of extreme stress are generally reduced or stopped after the cause is removed.

In case of delusions; it is noted that a remission of delusional symptoms occurs in up to 50% of the affected persons. However, because of the patients’ powerful belief in the reality of their delusions and a lack of insight in to their condition, individuals with such disorder may never seek treatment or may be resistant to exploring their condition in psychotherapy.

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:February 2, 2019

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