When psychotic symptoms are not psychosis

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Psychiatrists spend a lot of time talking with people who have unusual sensory experiences and thought processes. Some, but not all, will have a disorder of the mind we call psychosis. How we differentiate people into categories of psychosis and non-psychosis is not straightforward but feels clinically intuitive.

Below, I will describe examples of ‘non-psychosis’ psychotic symptoms and how these might affect our conceptualisation of the psychosis continuum.

What we mean by psychosis

Psychosis is an umbrella term for a number of conditions, akin to how ‘dementia’ encompasses Alzheimer’s disease, vascular dementia and Lewy body disease. When psychiatrists talk about psychosis we are really referring to a range of different psychotic disorders.

At the heart are disorders like schizophrenia and schizoaffective disorder, as well as less specific diagnoses like nonorganic psychosis or first episode psychosis.

We sometimes include other disorders like depression and bipolar disorder when they have specific psychotic features. We may also include psychotic episodes that are specifically caused by a drug, such as methamphetamine or cannabis.

When we talk about psychotic symptoms, we are most commonly referring to hallucinations and delusions - see this description from the NHS:

The two main symptoms of psychosis are:

• hallucinations – where a person hears, sees and, in some cases, feels, smells or tastes things that do not exist outside their mind but can feel very real to the person affected by them; a common hallucination is hearing voices

• delusions – where a person has strong beliefs that are not shared by others; a common delusion is someone believing there's a conspiracy to harm them

We can be even more specific and define a hallucination as a sensory perception in the absence of stimulus and a delusion as a fixed, false, idiosyncratic belief.

You may think experiencing hallucinations and delusions are specific to the psychotic disorders I mentioned above but they are remarkably common in other circumstances.

Psychotic symptoms in physical illness

Consider an 80-year-old lady, a retired teacher, who is admitted to hospital for a hip replacement. She is usually in good health and has no past history of mental illness.

While recovering from the operation, she reports that the nurses are trying to harm her by switching her medication for poison. At night she becomes agitated, shouting that the doctors are imposters. She can’t be convinced otherwise; despite being shown the medical staff’s ID cards.

In this scenario, the patient may have textbook symptoms of psychosis, but you’d get strange looks from hospital doctors if you described her as experiencing a psychotic episode.

This is a case of delirium, a fluctuating confusional state which can often be accompanied by paranoia and conspiratorial beliefs as described above. Here, the underlying cause could be post-operative infection, pain, or changes in medication. Older people are particularly vulnerable to delirium but it can occur in younger age groups too.

Psychotic symptoms in alcohol withdrawal

Now imagine a 50-year-old man who is admitted to hospital after being involved in a car accident. Over the next couple of days he develops a tremor, reports seeing small animals in his room and feels like something is crawling under his skin. At this point it is noted that he is a heavy, daily drinker and is treated for alcohol withdrawal with benzodiazepines.

In this case, the patient experienced these symptoms after abruptly stopping drinking. His brain had developed a tolerance of alcohol, through down-regulation of GABA-A receptors.

Although technically experiencing symptoms of psychosis, the clinical picture should immediately point to the diagnosis of ‘delirium tremens’, a medical emergency that requires prompt treatment with GABA-A agonists to prevent seizures and death.

Diagnostic classification systems tend to get round the above scenarios by stipulating that psychotic disorders do not occur exclusively in the course of a delirium.

Clinicians should always keep in mind the potential physical causes of psychosis. What about psychotic symptoms caused by other mental disorders that we wouldn’t consider ‘psychotic’.

Psychotic symptoms in other mental disorders

There are various disorders that are associated with hallucinations that we wouldn’t categorise as psychosis. A good example is borderline personality disorder, in which patients commonly hear voices. One survey published in Scientific Reports found 43% of patients with this disorder reported hallucinations, usually in the form of derogatory voices.

At this point, it is worth pointing out the importance of phenomenology (the descriptive assessment of a patient’s subjective symptoms). Classically, the auditory hallucinations of disorders like schizophrenia are vivid, concrete and indistinguishable from a true perception. They occur in ‘external space’, as if they are being heard through the patient’s ears.

By contrast, the voices heard in borderline personality disorder will often be recognised as coming from the patient’s own mind and will not have the quality of a true perception. Sometimes, they are disparagingly described as pseudohallucinations, as if they are not proper hallucinations.

However, there are limits to categorisation based on symptoms alone. In reality, psychopathology is often reported by the patient in vague terms that do not neatly fall into textbook definitions. It is often the context of the symptoms that will determine how we interpret them.

For example, a patient reporting a voice as: ‘coming from inside my head, telling me to harm myself’ would be interpreted differently if it was reported by a 20-year-old who had recently dropped out of university and was spending increasing amounts of time isolated in their room, compared with a 35-year-old who was reporting it in the context of repeated overdoses, self-harm, relationship breakdowns and chronic feelings of emptiness.

Even without knowing other details like developmental history, family history or drug use, the first patient would be more likely to be categorised as having a psychotic disorder, while the second is more likely to be experiencing auditory hallucinations associated with borderline personality disorder.

Neurodevelopmental disorders like autism can result in auditory hallucinations too. We would seldom categorise these as psychosis, unless they are associated with other features of a psychotic illness like a deterioration in functioning.

As I have previously described, we can’t diagnose psychosis with a brain scan or any other investigation. So ascribing psychotic symptoms to one disorder or another is not an exact science. Like many areas of medicine, categories are blurred, overlapping and open to disagreement between clinicians.

Psychotic symptoms in healthy people

Psychotic symptoms are surprisingly common in people who are in good physical and mental health. More than a third of people experience hallucinations (often visual) in the sleep transition: hypnagogic hallucinations when falling asleep and hypnopompic hallucinations on wakening. They are regarded as a non-pathological and have no relation to mental or physical illness.

There is a proportion of healthy individuals who experience ‘psychotic like experiences’ unrelated to sleep. One large study by John McGrath and colleagues estimated the lifetime prevalence of these experiences at 6%. Hallucinations were reported more commonly than delusions; in 5% and 1% of participants, respectively.¹

Interpretation of these experiences may be dependent on cultural background. Hearing voices can have a spiritual or religious meaning in some traditions. Shamanism, for example, views voice-hearers as having a connection to the spirit world. Groups like the hearing voices network seek to de-pathologise the experience of auditory hallucinations, interpreting these as part of human variation rather than illness. Some of the people involved in this movement will have previously received a psychiatric diagnosis, but many have not.

The continuum of psychosis

In recent years the idea of the psychosis continuum has become influential. This supposes that psychotic symptoms exist as a distribution, with the more severe end representing disorders like schizophrenia and the less severe representing normal human experience. The big implication from this model is that psychosis is not a category in itself but is more like an extreme variant.

Are all psychotic symptoms on the same continuum as schizophrenia though?

As an analogy, we might think about chest pain as a spectrum from no pain to the most severe central crushing chest pain of a myocardial infarction. Certainly on that continuum would be other less severe cardiac conditions, like angina, causing milder pain. But there would also be other causes of chest pain, unrelated to the heart, such as pulmonary embolism. There may be benign conditions like costochondritis (inflammation of the rib joints), which although presenting with chest pain, is really nothing to worry about.

I wonder if psychotic symptoms should be seen in a similar way; some being part of severe mental illness like schizophrenia, some being part of other conditions like borderline personality disorder or a delirium, and some being a benign symptom. This would imply that, although superficially similar in their presentation, they have distinct origins in the brain.

Perhaps the strongest evidence against this view and in favour of the psychosis continuum would be finding subtle biological changes in healthy people experiencing psychotic like experiences similar to the changes seen in people with schizophrenia. There have been some studies suggesting genetic and brain abnormalities relating to schizophrenia are associated with psychotic like experiences in healthy individuals. But our understanding of the mechanisms underlying psychosis are still too rudimentary to make definitive conclusions.

Praecox feeling

Everyday clinical practice involves interpreting which psychotic symptoms are indicative of an underlying psychotic illness and which are not. The process of doing so, like many clinical decisions in medicine, owes a lot to experience and intuition.

From clinical experience, psychotic symptoms aren’t on a straightforward continuum from normal to severe mental illness. Some are indicative of a physical illness, others are a result of neurodevelopmental or personality disorders, others are due to intoxication or withdrawal of a substance.

On the flip side, there is something about the category of schizophrenia that is more than simply delusions and hallucinations. It may be the presence of thought disorder (where a patient’s speech seems jumbled and difficult to follow). Or the negative syndrome (lack of motivation, social withdrawal, reduced range of emotion). Or cognitive dysfunction. Or a dissolution in boundaries between the self and environment.

The Dutch psychiatrist Hernicus Rümke argued that most diagnosticians are unable to articulate how they reach a diagnosis of schizophrenia. He coined the term, ‘praecox feeling’,² for the dissonance felt within the clinician when interviewing someone with schizophrenia - a sense of being unable to fully connect with the patient’s personality. It implies that there may be something about a patient’s experience of psychosis that, for the clinician, is fundamentally un-understandable.

1. Note that the lifetime prevalence of schizophrenia and related disorders is around 0.5%

2. The ‘praecox’ part comes from the old term for schizophrenia, dementia praecox, meaning precocious dementia