Does PTSD cause hallucinations?

Hallucinations are sensory experiences, where an individual feels or senses something that isn’t really there. They are technically classed as a symptom of psychosis, however, there is evidence of a relationship between PTSD and psychosis.  ^[1]

Types of hallucinations

Hallucinations can be broken down into five categories:

• Auditory – when an individual can hear sounds that are not there(g. music, voices, sound effects) 
• Visual – when an individual sees things that aren’t there (g. people, lights, objects)
• Olfactory – when an individual smells something which is not there
• Gustatory – Tasting something without eating or drinking anything
• Tactile – feeling that something is on or under your skin when there is nothing there

The link between PTSD and hallucinations

Auditory hallucinations are typically the type of hallucinations experienced by someone with PTSD. Almost all veterans and approximately two-thirds of civilians with a diagnosis of PTSD have reported experiencing auditory hallucinations ^[3].

Not much is known about why PTSD sufferers experience hallucinations. However, researchers believe that the trauma may influence how hallucinations are experienced in a few ways:

• Insights from predictive coding – Predictive coding is when the brain actively tries to predict what is about to happen. For someone with PTSD, this predictive ability may have been changed due to a traumatic event. This could leave the predictions to become substantially different from reality, causing confusion and, in some cases, ^[1]
• Changes in mindset – A negative change of mindset for an individual will affect cognitive decisions and general mood, increasing the body’s stress response. As the mind interprets reality through an increasing negative lens, it can start to separate from reality increasing the likelihood of hallucinations. ^[3]
• Intrusive thoughts – Hallucinations may occur because of intrusive thoughts that haven’t been contextualised. Intrusive thoughts provoke fear as a response to trauma. As these mix with current memories, they can consolidate and alter the memory and emotional well-being of the individual and potentially cause hallucinations. ^[3]

The likelihood of hallucinations is increased depending on the following factors ^[3]:

• Certain traumatic experiences – such as child abuse or war trauma, may increase the risk of experiencing hallucinations.
• Avoidance behaviours – If the individual avoids thinking about or emotionally distances themselves from their traumatic experience, they are more likely to suffer from intrusive thoughts increasing the risk of hallucinations.
• Emotional dysregulation – Individuals who become extremely upset when reliving a traumatic event are four times more likely to experience auditory hallucinations.
• Anxiety and depressive symptoms
• Delusional beliefs – These are beliefs that are not founded in reality and believed by the individual even in the face of contrary evidence. These false ideas can be about themselves, others, or their environment.
• Dissociation – When an individual enters a psychological state that disrupts or discontinues consciousness.

Delusions are another positive psychosis symptom, and if experienced, increases the likelihood of hallucinatory episodes, while dissociation is also associated with psychosis.