Hallucinations relate to disturbances in sensory experiences, while delusions affect a person’s innate beliefs and mental constructs. These may occur due to a mental health disorder, substance use, certain medications, or other medical conditions. Both are typically treated with medications, alongside certain therapeutic modalities.
What Are Hallucinations?
Hallucinations are sensory experiences, in any sensory modality—sight, sound, taste, touch or smell—that generate a perception of things that aren’t really there. Hallucinations are different from perceptual illusions in that they occur without a sensory stimulus present, whereas illusions are misinterpretations of real sensory stimuli.
As a symptom of psychosis, hallucinations can be caused by mental illness, substances, or other medical conditions. When two or more people share a hallucination, it is referred to as shared psychosis, or folie-a-deux in the case of two people.
The most common types of hallucinations include:
- Auditory hallucinations: Hearing sounds or voices that aren’t really there, like the voice of a deceased person.
- Tactile hallucinations: Feeling that one is being touched by something that is not present. Common tactile hallucinations include feeling insects crawling on—or under—one’s skin (i.e., formication) or being tapped on the shoulder by someone who isn’t there.
- Olfactory hallucinations: Smelling a scent for which there is no real source, such as smoke, perfume or a particular food.
- Visual hallucinations: Seeing objects, people, shadows or movement in an object that are not seen by others looking at the same space. As with other symptoms, it is important to rule out other sources of perceptual distortion, including physiological conditions of the sense organs.
- Gustatory hallucinations: Experiencing taste in one’s mouth in the absence of any real source, like tasting metal or poison in one’s food in the absence of evidence. This type is more commonly drug induced.
- Kinesthetic hallucination: A faulty perception of body movement, such as feeling like one is falling when they are still, or running really fast when one is walking slowly. When this occurs with limb amputations, it is referred to as “phantom sensation,” which can involve movement, tactile or pain (i.e., phantom pain) sensation.
- Multimodal hallucinations: Sensory experiences in more than one modality at once or sequentially, such as hearing commands from a historical figure who one sees walking into their room, or seeing a creature that smells foul.1
What Causes Hallucinations?
While hallucinations are a classic symptom of certain mental illnesses, like schizophrenia and bipolar disorder, they can also occur for a number of other reasons. Those who experience medical conditions, physical and psychological stress, and vitamin deficiencies may also experience hallucinations.
Some research suggests that regardless of the trigger, hallucinatory experiences may result from altered connectivity between brain regions, thus leading a person to misattribute a self-generated thought to an external source (e.g., another’s voice).2
Hallucinations may occur as a result of:
- Substance use: A variety of substances can cause hallucinations, including prescribed medications, recreational drugs (licit and illicit), and toxins. When this occurs, it is referred to as drug-induced psychosis. Drugs of misuse can trigger hallucinations during acute intoxication, frequent use, as well as withdrawal. In most cases, symptoms will subside with detoxification and abstinence from the substance.
- Medications: Certain prescribed medications can have psychotic side effects.3
Examples include certain beta blockers, antidepressants, muscle relaxants, stimulants, ,and even certain antivirals and antibiotics.3,4,5,6
- Mental health condition: Although hallucinations are a key feature of schizophrenia (prevalence: 60-70%), they can also occur in other mental health disorders, such as schizoaffective disorder, bipolar disorder, schizotypal personality disorder, and eating disorders.2
- Neurodegenerative disease: Dysfunction of brain pathways involved with sensation and perception can cause hallucinations. Although not all cases of neurodegenerative disease present with hallucinations, they can occur in a portion of individuals with dementia, post-traumatic stress disorder (PTSD), Parkinson’s disease, Alzheimer disease, and Huntington disease.7,8
- Medical conditions: Other medical conditions that can cause hallucination include epilepsy, brain tumors, traumatic brain injury, thyroid dysfunction, Hashimoto encephalopathy, chromosomal disorders, and autoimmune disorders.9,10,11,12,13
- Sensory disorders: Although many sensory disorders do not result in hallucinatory experiences, they have been reported in cases with hearing impairment, eye disease, deafness, and tinnitus.1,15,16
- Sleep-related conditions: Research suggests that sleep deprivation or lack of sleep, sleep paralysis, and narcolepsy can produce hallucinatory experiences.17
- Physical and psychological Stress: Stress can trigger physiological changes in the brain and body. Although fairly rare, extreme cases of psychological stress incurred by sensory deprivation, fatigue, bereavement, and physical or sexual abuse can lead to hallucinations.18,7
- Vitamin deficiencies: Although the research is mixed, it has been suggested that Vitamin B12 and D may be related to hallucination proneness.19,20
What Are Delusions?
Delusions are distorted beliefs that, despite possibly having a kernel of truth, are not supported by the overwhelming evidence accessible to most typical observers. These beliefs may be persecutory, referential, grandiose, erotomanic, nihilistic or somatic in nature. They can range from clearly bizarre and implausible–such as a tracking device being implanted in one’s brain without any scar or sign of surgery–to non-bizarre but still highly unlikely–such as being surveilled by police without having done anything wrong.
Four key features that can help identify a belief as delusional:21
- The overwhelming majority of one’s non-psychotic peers agree that it has no merit.
- It’s idiosyncratic or specific to the individual.
- It’s illogical.
- It’s stubbornly maintained and unshakeable, despite evidence to the contrary.
Common types of delusions include:
- Persecutory delusions: A firm and often unshakeable belief that one is in danger of being harmed or ruined (perhaps in reputation) by another person, group, organization. As the most common delusional theme, these beliefs can range from elaborate, conspiratorial plots to the more mundane suspicion that one’s spouse is poisoning their food.
- Referential delusions: Beliefs that one is the intended recipient of certain cues, signs, and gestures from external sources, especially in media. For example, it may be a newspaper article containing secret coded instructions for a person to solve.
- Grandiose delusions: Also called delusions of grandeur, these are beliefs that one is significantly more important than they really are. These inaccurate self-assessments might concern one’s abilities or be related to wealth and fame, despite clear evidence to the contrary.
- Erotomanic delusions: Inaccurate beliefs that another person, often a highly respected person in one’s social circles, is in love with them.
- Nihilistic Delusions: Fixed beliefs that a major catastrophe will imminently occur, such as a nuclear bomb or asteroid hitting the earth, despite the lack of valid evidence.
- Jealous delusions: Persistent and even obsessive ruminations that a significant other, spouse, or friend is not being faithful in a relationship, despite no supporting evidence. These delusions may also take the form of believing that other people are jealous of them for various reasons, and that the “jealous” individuals are out to get them.
- Somatic delusions: Unshakable beliefs about one’s health or body despite a lack of medical evidence. For example, a person could be convinced of having a tumor when tests show no sign of one. In other cases, people may see deformities on their body that no one else sees.
- Mixed delusions: When a person has multiple delusions that are not specific to a single category, it is referred to as “mixed delusions” or “unspecified.” For example, a person may believe that a television news anchor is in love with him or her (i.e., erotomanic) and that this person has hired secret agents to spy on the person’s whereabouts (i.e., persecutory).
What Causes Delusions?
Delusions can be conceptualized as occurring on a spectrum. We all may experience some inaccurate thoughts about ourselves, like having a better singing voice than we do (especially when singing alone in the car). However, when these distorted beliefs interfere with daily living, relationships, and personal or vocational goals, they are considered a symptom of a mental health disorder. Delusions can also occur as a result of substance use, both recreational and medicinal.
Delusions may occur as a result of:
- Bipolar psychosis: Psychotic symptoms in bipolar disorder, including hallucinations and delusions, are more likely in the context of a manic episode than a depressive episode.
- Schizophrenia: Delusions in schizophrenia can result from numerous sources, including neurological impairments; the cumulative effects of thought disordered thinking; cognitive impairments; poor reality testing; and a rapid flight of ideas.
- Delusional disorder: Delusions within the context of delusional disorder can be related to a combination of factors, including tendencies toward obsessional thinking; social reinforcement of delusional beliefs; neurological impairment; mania or hypomania; delirium; and the exaggeration of legitimate cultural or religious beliefs.
- Mental health condition: Schizophrenia spectrum disorders (e.g., schizophrenia, delusional disorder); bipolar disorder; schizotypal personality disorder; and eating disorders can all have delusions as a symptom.
- Substance use: A variety of substances can cause delusions, including prescribed medications, recreational drugs and toxins. Drugs of misuse can trigger delusional thoughts during acute intoxication, repeated use, and withdrawal.
- Neurodegenerative disease: Brain dysfunction of the frontal lobe and the limbic areas can cause delusions. Delusions can occur for those with dementia, post-traumatic stress disorder (PTSD), Parkinson disease, Alzheimer disease, and Huntington disease.7,8
What Is the Difference Between Hallucinations & Delusions?
Hallucinations and delusions both reflect distortions of reality common to psychosis. While hallucinations are faulty sensations, delusions are faulty beliefs. They can occur simultaneously in the same person and at the same time, or they can occur individually.
Although both of these symptoms are caused by dysfunctions in the connectivity of the frontal, limbic, cortical, and subcortical brain regions, the precise neuropathology may vary depending on the cause and the content of the symptom. For example, auditory hallucinations may involve problems with the connectivity to the auditory cortex, while visual hallucinations may stem from occipital-cortex dysconnectivity.
How Are Hallucinations & Delusions Diagnosed?
There is no single diagnostic test to determine whether someone is having a hallucination or delusion. Rather, a battery that may include include projective personality measures–like the Rorschach and the Thematic Apperception Test (TAT), as well as objective personality tests, like the Minnesota Multiphasic Personality Inventory (MMPI)–is commonly used to evaluate these symptoms and may offer clues as to what might be causing them.
The diagnostic process for hallucinations and delusions may include:
- Psychiatric evaluation: A psychiatric evaluation usually consists of speaking with a psychiatrist or psychologist about what the individual is experiencing, and engaging in neuropsychological testing (i.e., series of brief activities and puzzles that are used diagnostically to assess brain function in a non-invasive way).
- Speaking with family: Delusions and hallucinations feel very real to the person experiencing them and it can be difficult for a clinician to assess the veracity of an experience in any given moment. Having a family member or friend present to provide clinicians with an additional perspective and context can be helpful for diagnosis.
- Blood tests: Diagnostic blood tests can help assess the presence of psychosis-inducing substances, hormone levels, infection, medical conditions, malnutrition, and genetic risk for schizophrenia.
- Urine & other relevant screens: Toxicology screens can help determine if drugs or other medical conditions may be underlying symptoms of psychosis.
- Imaging scans: Neuroimaging (e.g., MRI, PET, CT) scans can help detect abnormal brain tumors or cysts that may be putting pressure on surrounding brain tissue and causing psychotic symptoms.
Hallucinations & Delusions Treatment
Treatment for hallucinations and delusions will depend on the underlying cause. In the case of substance-induced symptoms, relief can come with detoxification and abstinence. However, if the substance use is part of a larger problem with misuse and dependence, an integrated treatment program for both drug misuse and mental illness may be recommended. If the underlying cause is psychiatric, medication is usually the first line of treatment, but is most effective when integrated with therapy and skills training.
Symptoms of psychosis can be very distressing and disrupting to daily life for both the individual and family. Establishing a treatment plan targeting the underlying cause is key to a positive long-term outcome. A successful treatment plan is usually multifaceted and may include individual, family and group therapy, medication management, stress management, and drug rehabilitation if applicable.
Pharmaceutical treatment is often the first and most effective means of alleviating psychotic symptoms, assuming the underlying cause is not situational or related to an external agent. A skilled psychiatrist can help figure out the best pharmaceutical regimen for the individual. If you have trouble finding a psychiatrist near you, you may want to consider online psychiatry options.
Medications that may be prescribed in the treatment of hallucinations and delusions include:
- Typical antipsychotics: First-generation or typical antipsychotic medications work by reducing dopamine levels. Typical antipsychotic medications have numerous serious adverse effects such as tardive dyskinesia, which involves involuntary movements.
- Atypical antipsychotics: Second-generation or atypical antipsychotics work differently from first-generations, modulating both serotonin and dopamine. Though they have a reduced propensity to cause certain side effects like tardive dyskinesia, they come with their own set of adverse effects, including severe weight gain and other metabolic issues.22
- Antidepressants/anti-anxiety medications: Other medications commonly used for depression and anxiety may also be used to treat anxiety and depression that can co-occur with psychotic symptoms, or to preempt positive symptoms that may be triggered by intense anxiety.
- Injectables: Since antipsychotic medications often come with unpleasant adverse effects, compliance can be a problem. Recently, clinicians have been developing longer-acting doses that can be injected by medical professionals to avoid reliance on regular daily adherence by the individual with psychosis.23
- Cannabidiol (CBD)*: There has been considerable optimism recently for the use of CBD as a relatively safe and tolerable therapeutic to treat hallucinations and delusions. In fact, a number of studies have shown CBD to be as effective as some antipsychotic drugs (e.g., amisulpride) and without as many adverse effects.24,25
*Please note that most CBD on the market is not regulated and many products have been found to have inaccurate dose information. Furthermore, CBD does have side effects as well and can interact with other medications. It is always recommended to consult with your doctor before using.
Alongside medications, therapy can be beneficial in the treatment of hallucinations and delusions. Engaging in therapy allows a person to share their distorted beliefs or sensory experiences with an objective outsider who can help them see the faults in their perceptions. This can also provide a place for family members to participate in a loved one’s treatment and provide additional support. While finding a therapist can be daunting, you can start by using this online therapist directory.
Therapy options for hallucinations and delusions may include:
- Behavior therapy (BT): BT can offer patients concrete rewards for concrete behavior successes, like achieving hygiene goals and others that can be problematic among those with psychosis and substance abuse disorders.
- Cognitive behavioral therapy (CBT): CBT can help individuals learn to perform reality testing on their hallucinations and delusions—particularly paranoid delusions.
- Family therapy: Family therapy can help family members create an environment of support and positivity that reduces anxiety, anger and confusion, thus preventing the symptoms before they arise.
- Group therapy: Realizing that one is not alone in their experience can help them to feel more comfortable addressing their symptoms. Also, recognizing and identifying paranoid thoughts in others may help in bringing perspective to one’s own thoughts of paranoia.
- Psychodynamic therapy: While not typical for certain psychotic disorders, psychodynamic therapy can sometimes be helpful with patients who have good insight to recognize how their symptoms may be related to past traumas that haven’t been fully examined or acknowledged.
- Social skills training (SST): SST can be particularly useful—especially in conjunction with psychotherapy and medication—to help the individual develop skills that are often deficient in certain psychotic disorders.26
Hallucinations and delusions can feel frightening, for both the person experiencing them and their family and friends. These symptoms can also give rise to dangerous behaviors. If someone whom you care about is at risk for harming themself or others, call 911 or go to the nearest emergency room.
The main purpose of hospitalization is to stabilize the individual and the duration will vary depending on the cause and responsiveness to acute treatment, but may last days to a couple of weeks. Once stabilized, outpatient resources–such as therapy, skills training and other services–can be provided to support the individual and their family moving forward.
Rehabilitation & Support
Support services may include online support groups, rehab, the National Alliance on Mental Illness (NAMI), and one’s local Department of Social Services. Additionally, having family members join for therapy appointments can make a big difference in the treatment outcome for individuals with psychotic symptoms, as they may be unaware of certain symptoms or the degree to which they interfere with daily functioning. Coping strategies work best when relatives are involved, educated about the illness, and equipped with coping strategies themselves.27
Hallucinations and delusions can take many forms and occur with varying frequency and intensity depending on the individual and the cause. These faulty sensory experiences and beliefs feel very real to the individual and can be quite distressing and disruptive. However, it is prudent to seek help or evaluation if you or someone you care about is struggling with these symptoms. If one’s hallucinations or delusions become severe and there is risk for harm, call 911 or go to the nearest emergency room.