Symptoms or conditions mistaken for dementia

Expert reviewers, Dr Pravir Sharma, Consultant in Mental Health and Old Age Psychiatry and Dr Adrian Raby, General Practitioner
Next review due December 2024

Dementia can sometimes be difficult to spot because it develops slowly, especially in the early stages. It’s also easy for people to mistake dementia signs for another problem or health condition and to mistake the signs of a different problem for dementia.

This page gives an overview of problems that may cause similar symptoms to dementia.

Hands of an elderly woman

Why dementia can be difficult to spot

There are several reasons why dementia can be difficult to spot.

There are many different signs and symptoms of dementia and quite a few of them are non-specific. That means they’re general symptoms such as disturbed sleep, forgetfulness and low mood. Many of these are found in conditions other than dementia. Symptoms also appear slowly and develop gradually, making them difficult to spot.

A doctor won’t be able to diagnose dementia based on one specific symptom. They do several tests to find out if someone’s symptoms are caused by dementia or something else. Tests include:

  • a physical examination
  • questions about general health and symptoms and how these have changed over time
  • blood and urine tests to rule out other conditions and causes
  • cognitive assessments – these tests look at mental abilities, including memory and language

As we get older, it’s common to become a little forgetful especially if we’re stressed or have been ill. Although dementia is closely linked to age, it’s different from this normal age-related memory loss.

In older age, we’re also more likely to develop other conditions that can easily be mistaken for dementia. These include conditions such as depression and delirium. If someone with dementia develops another condition, that can sometimes be missed if the symptoms are similar.

If someone has symptoms that may be dementia, it’s important that a correct diagnosis is obtained or dementia be ruled out. This page explains some of the conditions and situations that can be mistaken for dementia. You might find it helpful to learn about rarer causes of dementia too.

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Conditions that may be mistaken for dementia


Delirium is a change in mental state or consciousness. It develops quickly and can become very serious. As with dementia, people with delirium often become confused and may have problems with memory and understanding. Sometimes their personality changes too.

Delirium is more likely to develop in older people and those who live in residential or nursing homes. It’s often caused by a sudden illness such as an infection, severe pain or heart attack. It’s usually temporary and it can be treated if it’s found quickly.


Depression is an illness where you have a continuous low mood and/or a loss of interest and enjoyment in your life. It’s probably the condition that is most mistaken for dementia. Symptoms such as disturbed sleep, low mood and not taking care of yourself are common for both. Many people with depression, especially older people, also have memory loss and feel disorientated.

Doctors can find it hard to distinguish between the two conditions. It’s also possible to have depression and dementia at the same time, and for depression to appear before dementia develops.


Everyone feels anxious from time to time. But generalised anxiety disorder is a more extreme and long-lasting kind of anxiety. Symptoms can be like those of dementia. They include restlessness, finding it hard to concentrate and having disturbed sleep. People with dementia often have anxiety too, which can make the situation more unclear.

Your doctor may suggest a treatment called cognitive behavioural therapy for anxiety. It’s a way of talking about thoughts, behaviours and feelings. There are also many things people can do to help themselves, including relaxation or meditation and being active.

Mild cognitive impairment (MCI)

Mild cognitive impairment is common, especially in older people. It’s when you become forgetful and your thinking is affected, but usually not enough to affect day-to-day life. The symptoms are usually worse than you might have naturally as you age, but not severe enough to be dementia.

The symptoms can look like the early stages of dementia, but they can be subtle and hard to spot. People affected by this condition may have problems with:

  • thinking and focusing; for example, following conversations
  • language; for example, finding words
  • memory loss
  • becoming disorientated or getting lost in familiar places

People with MCI are more likely to develop dementia, but it doesn’t mean they will. Some people get better because their symptoms were caused by an underlying health problem. Some find their symptoms stay the same and others will find the symptoms get worse and progress to dementia.

There is no specific medical treatment for MCI. But your doctor may suggest activities and lifestyle changes that may slow or prevent the progression to dementia. These include eating healthily and being physically and mentally active.

Hormone (gland) conditions

Some hormone conditions can cause dementia-like symptoms. These include:

  • underactive thyroid gland (hypothyroidism)
  • overactive thyroid gland (hyperthyroidism)
  • Cushing’s syndrome (a condition caused by having too much cortisol hormone in your body)
  • underactive pituitary gland
  • porphyria (when your body is unable to produce enough of a substance called haem)

Other problems that may be mistaken for dementia

Memory changes that happen with age

As we get older, our memory naturally starts to get a little worse. But there is a difference between these expected memory problems and dementia symptoms. Forgetting your keys or walking into a room and forgetting what you went in there for are normal memory lapses. But if memory lapses are starting to affect everyday life and are getting worse, they may be a sign of dementia.

Reactions to medication

Many medicines can affect the way the brain works. This can cause side-effects that are like the symptoms of dementia. Groups of medicines that can do this include:

Older people often take several different medicines together to treat different conditions. They’re more likely to have side-effects because these medicines can interact with each other. Older people may also be more likely to develop side-effects because their bodies can’t process and get rid of medicines very well. Confusion is one of the most common side-effects. These interactions are easy to mistake for some of the symptoms of dementia.

When a doctor is assessing someone to see if they have dementia, they should ask about the medicines they’re taking.

Lack of vitamin B12 and lack of thiamine (Vitamin deficiency)

Vitamin B12 is found in meat, fish, eggs and cheese. Thiamine is also a B vitamin and is found in whole-grain foods, some breakfast cereals, beans and peas, nuts and seeds.

Both are important for a healthy nervous system. If someone doesn’t get enough of either of these vitamins, they can have symptoms that could be mistaken for dementia. These include confusion, memory loss, irritability and a change in mental state.

Head injury

An injury caused by a major blow to the head, such as during a car accident, can cause dementia-like symptoms. These can also develop if someone is having repeated smaller head injuries over time. This can happen playing contact sports where there is a collision between people, such as rugby and ice hockey. Symptoms include memory problems, mental slowness, feeling emotionally up and down and a bit ‘foggy’.

Hearing or eyesight problems

Problems with hearing or eyesight reduce someone’s ability to take in information. That can make it look like their mental ability is affected.


Drinking too much alcohol can also lead to the development of similar symptoms to dementia. In the long term, regularly drinking too much causes brain damage that can lead to dementia. It can also cause a lack of thiamine, which can cause dementia-like symptoms. Following sensible drinking advice before this becomes a problem may help.

Going for an assessment

The list of conditions and problems above isn’t everything. There’s a whole range of things that can occasionally cause dementia-like symptoms for some people.

There isn’t always a quick answer to the question, Is it dementia or something else? If someone has dementia-like symptoms, the most important thing to do is see their GP for a full assessment.

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Related information

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  • Expert reviewers, Dr Pravir Sharma, Consultant in Mental Health and Old Age Psychiatry and Dr Adrian Raby, General Practitioner
    Next review due December 2024