Noticeable shifts in usual behaviour or emotions
In some neurological conditions such as dementia, personality changes can occur because parts of the brain that control judgement, emotions, empathy and social behaviour are affected. A person may seem ‘not like themself’.
Family and friends may notice:
- apathy – less motivation, less interest in hobbies or reduced initiative
- changes in habits – new rigid routines, reduced flexibility or changes in food preferences
- disinhibition – saying or doing things that are rude, risky or out of character
- mood changes – irritability, depression, anxiety or rapid mood shifts
- reduced empathy – less caring or awareness of others’ feelings
- social withdrawal – avoiding people, speaking less or making less eye contact
- suspicion or paranoia – believing others are stealing or lying.
Personality changes may be associated with:
- alcohol or drug use
- delirium (sudden confusion due to illness or infection)
- dementias including Alzheimer’s disease and frontotemporal dementia
- hearing or vision problems (these can increase withdrawal or irritability)
- poor sleep and sleep disorders
- stress or anxiety
- stroke and other neurological conditions.
When to seek help
You should seek medical assessment if personality changes:
- affect relationships, work or daily functioning
- appear suddenly over hours or days, especially with:
- a new medicine
- dehydration
- fever
- illness.
- are new, persistent or worsening
- include risk-taking, unsafe behaviour or aggression
- occur with memory loss, confusion, poor judgement or language problems.
Sudden changes can be delirium and may need urgent medical care.
Common patient questions
No. People may become a little quieter or slower with age, but clear changes in personality or social behaviour are not considered a normal part of ageing, especially if they interfere with daily life.
Yes, anxiety and depression can cause changes in personality (eg increased irritability, withdrawal or loss of interest). Sleep problems, alcohol, pain and some medicines can also affect mood and behaviour.
If changes persist or progress, it is important to get assessed.
They can be. In some dementias, personality and behaviour changes may appear early, sometimes even before obvious memory problems. This is particularly common in frontotemporal dementia.
In Alzheimer’s disease, personality changes can occur as well, often alongside changes in memory and thinking.