Delusions in dementia and mental health conditions

A delusion is a belief that has no basis in reality. Along with hallucinations, they can be a key sign that someone is in a state of psychosis, which is when they lose their grip of reality. People may have delusions if they are living with dementia.

Having a delusion doesn’t necessarily mean someone is mentally ill or has memory problems. It’s human nature to believe what we want to believe, and to seek out evidence to support that belief while avoiding or dismissing evidence to the contrary.

It’s hard to pinpoint exactly when a belief becomes a delusion. We wouldn’t call someone who believed in ghosts deluded or children who believe in Father Christmas delusional. A belief is considered a delusion when it has no basis in reality and is not part of the person’s culture, subculture or education.

Delusions and dementia

People living with dementia may experience delusions due to their poor memory, false memories (confabulation) or hallucinations.

Memory loss can cause events to become simplified and blended in a person’s mind. If they experience confabulation, their brain can create false memories to fill the gaps left by lost true memories. Memory loss can create a patchwork effect. The person may unconsciously piece together a few distorted memories to create something new and believe this patchwork memory is the true course of events.

People living with dementia can lose the ability to apply rational thought and reasoning to a false belief. 

Delusions and mental health problems

Mental health issues that can carry delusions as a symptom include:

• Schizophrenia
• Bipolar disorder
• Anxiety disorder
• Depression

Delusions in people with mental health issues are often related to emotions rather than memories. They can occur in someone who does not have a mental health condition but has generally poor mental health. 

Various studies have recognised that delusions are more common in people who have low self-esteem. These can be negative beliefs borne from their low opinion of themselves, such as believing their friends meet up without them to laugh at them, or quite the opposite. Sometimes people with low self-esteem can experience delusion as a defence.

Types of delusions

These are common types of delusions in people with dementia and/mental health problems.

Grandiose delusions

Grandiose delusions are when a person has false beliefs that they are superior to others. This usually comes across as self-absorbed behaviour and being deluded about their own intelligence, skills or looks. Grandiose delusions can cause somebody a lot of problems in their social life, particularly if they mistreat or patronise others.

Symptoms of grandiose delusions overlap greatly with narcissistic personality disorder.

They can include:

• Boasting about their own achievements or past experiences, often largely exaggerating them to make themselves look better
• Dismissing or criticising the achievements or strengths of others, and being overly critical of their character/looks etc
• Reacting angrily and defensively to any challenge to their behaviour or beliefs
• Being unable to see how their words and behaviour affect others, or not caring 
• People with grandiose delusions can be automatically selfish, it may not cross their mind to put somebody else first
• Believing their own delusions, when everyone around them can see the beliefs have no basis in reality
• Breaking the law (or other rules) and believing they won’t get caught because they are more intelligent than the police/entire British legal system
• Believing they are more intelligent than others, often than those who disagree with them

The key difference between delusions of grandeur and narcissistic personality disorder is that delusions are more likely to be temporary and accompanied by reckless behaviour, while a narcissist will show these behaviours for years on end, without ever maturing out of them or having the self-awareness to see that the behaviours are problematic and seek help.

Grandiosity is common in people with bipolar disorder, with around two-thirds of people with the condition experiencing grandiose delusions during an ‘up’ or manic episode.

Erotomania

Also called De Clérambault syndrome, erotomania is when somebody has the delusional conviction that someone is in love with them.

It is common for people to mistakenly believe someone they are romantically interested in likes them back. It can be hard to believe that intense romantic feelings are one-sided, and it’s easy to overanalyse conversations and look for signs of reciprocation, while ignoring the glaringly obvious truth that they’re not into you. In erotomania, however, the delusion of love has no basis in reality and the person usually acts on the delusion with irrational behaviour.

In erotomania, the object of the person’s affections may not even know who they are. They are usually somehow out of reach, such as they are not at all romantically interested in the person, they are much older or younger, they are married or even they are a celebrity or public figure.

The person becomes utterly convinced that their love is reciprocated, showing symptoms such as:

• Planning their future together as if they are a couple, such as planning their wedding, where they’ll live and their children’s names
• Believing the reason they are not together is that it is forbidden by someone or something, not because the other person isn’t interested
• Harassing the person with messages, gifts, letters or showing up at their door
• Other stalking behaviour, such as spying on them or hacking into their social media accounts
• Unreasonably jealous behaviour if the person is seeing someone else or is married, such as insisting the person is cheating on them or that their partner is an abuser, forcing them to be in a relationship against their will
• Looking for signs everywhere that the person is trying to communicate with them

Paranoid and persecutory delusions

These are founded in worry and anxiety. They are a key characteristic of paranoid schizophrenia but can happen in people without the condition as well.

Paranoid delusions are beliefs that the person is in some form of danger, when in reality they aren’t or are at very low risk. For example, worrying that the aeroplane you’re on could crash is pretty normal, but a paranoid delusion might be the unwavering belief that it will. 
Persecutory delusions are a little more specific, they involve an unfounded belief that someone (or a group of people or organisation) is conspiring to harm them in some way. They are a form of paranoia that include a perpetrator.

Symptoms of paranoid and persecutory delusions include:

• False beliefs of others out to get the person
• Ruminating beliefs/worries that something will happen, like a break-in
• Feeling suspicious of others in public, having thoughts that they aren’t safe around others
• Thinking that food or medicine is poisoned 
• Not trusting others
• Thinking others have an ulterior motive
• Accusing people of spying, or partners of cheating
• ‘Splitting’ on people – going from trusting and feeling safe with them to having thoughts that they are bad or that they want to hurt them
• Strange beliefs, like the world will end
• Thinking that people in the streets or cars driving behind them are following them

Paranoid delusions are different from paranoid personality disorder. People with this disorder are usually hypersensitive, cannot accept criticism, are generally mistrusting or suspicious of others and cannot comprehend anything being their own fault.

Somatic delusions

Somatic delusions are false beliefs that the person is ill, injured or their body is otherwise irregular. They are not the same as somatic hallucinations, but the person may experience both.

Somatic delusions are very rare. Even rarer, but in some ways a more extreme version of these, are nihilistic delusions. People with nihilistic delusions believe that part or all of their body is dead or not real.

There are two main types of somatic delusion – non-bizarre and bizarre.

Non-bizarre somatic delusions are about things that could feasibly happen but there is no evidence that they are happening, like someone believing they have cancer despite having no symptoms or any other evidence to suggest as such.
Bizarre delusions have no basis in reality and could never be true under any circumstances, for example, if someone believes that insects have crawled into their head and laid eggs in their brain.

Treatment for delusions in dementia and mental health conditions

Delusions can be treated by treating their underlying cause. This could be:

• Treating their psychosis with antipsychotic medication
• Treating a mental health condition with various therapies and medications
• While dementia is not treatable, therapies such as cognitive behavioural therapy can improve symptoms of delusions caused by dementia
• Addressing factors that are exacerbating symptoms, such as treatment programmes for people abusing drugs or alcohol