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Guide 1 of 5 · Diagnosis

Signs of dementia

About 3 minutes to read · Last checked September 2026

The main points

  • Early signs include forgetting recent events, getting lost, and struggling with everyday tasks.
  • Mood and behaviour can change too.
  • If you notice these signs, the person should see a health worker.
  • Other illnesses can cause similar signs, and some of them can be treated.

Changes to look out for

Everyone forgets things sometimes, but dementia is more than this. Look for changes that keep happening and get worse over months. These changes happen because the illness affects memory, thinking and judgement. The person may:

  • forget things that happened recently
  • lose or misplace things
  • get lost, even in places they know well
  • lose track of the day, month or year
  • find it hard to follow a conversation or find the right words
  • struggle with tasks they used to do easily, like cooking or handling money
  • find it hard to make decisions or solve problems
  • have trouble judging distances or steps

Changes in mood and behaviour

Dementia can change how a person feels and behaves, not only their memory. Families often notice these changes before the memory problems. This is because the illness also affects the parts of the brain that control feelings. The person may:

  • feel worried, sad or angry about their memory
  • seem like a different person
  • behave in ways that are not like them
  • stop seeing friends, or stop doing things they enjoyed

Important: sudden confusion

Sudden confusion is not usually dementia. If someone becomes confused over hours or a few days, it may be an infection or another illness. These problems can become serious quickly, but they can often be treated. Get medical help straight away.

What to do if you are worried

  • Write down what you notice. Note what happened and when. Our checklist to take to the health worker gives you a place to write it all down.
  • Talk gently with the person. They may be worried too.
  • Go with them to see a health worker. A clinic or hospital is a good place to start.

Not all memory problems are caused by dementia. Infections, low vitamin levels, thyroid problems, depression and side effects of medicines can cause similar signs. Many of these can be treated once they are found. This is why getting checked matters.

Read the next guide: getting checked by a health worker

This guide gives general information about dementia. It is not medical advice for any one person. A doctor, nurse or health worker who knows the person can give advice that fits them. Please speak to them about any worries.