Delirium, Depression, or Dementia: What's the Difference?

Delirium, depression, and dementia can look similar from the outside: confusion, withdrawal, changes in memory or mood. They are not the same conditions, and telling them apart matters, because the right response is different for each one. And sometimes, a person has more than one at the same time.

More details below.

Delirium

Delirium is a medical emergency. It's a sudden, often reversible state of severe confusion and rapid changes in attention, awareness, and thinking that develops over hours or days. Delirium is not the same as dementia, but a person living with dementia can also develop delirium, and it's often mistaken for their dementia "getting worse."

Symptoms:

• Sudden confusion
• Agitation, restlessness, hallucinations
• Fluctuating alertness, thinking, perception
• Changes in sleep
• Quick changes in mood

When to see a doctor: Right away. If someone shows sudden confusion, contact their health-care provider immediately. If they're in hospital or long-term care, tell staff immediately. Older adults in these settings are at higher risk for delirium.

Depression

Depression is more than feeling sad. It's a medical condition where a person feels continuously low, loses interest in things they used to enjoy, and struggles with energy, sleep, or concentration for weeks at a time. It affects how a person thinks, feels, behaves, and even how their body feels.

Symptoms:

• Depressed mood
• Losing interest in things
• Reduced memory and concentration, low self-esteem, disturbed sleep
• Over- or under-eating
• Possible suicidal ideation

When to see a doctor: Depression should always be taken seriously. Talk to a health-care provider if you or someone you know is showing signs of depression. There are many effective treatment options.

Dementia

Dementia is a group of symptoms that can be a gradual, progressive decline in how the brain processes information. It can affect short-term memory, communication, language, judgment, reasoning, and the ability to think through complex ideas. Over time, it can also affect long-term memory and the ability to carry out familiar, everyday tasks. Changes in mood and behaviour can occur too.

Common Symptoms:

• Difficulty performing familiar tasks
• Memory loss that affects day-to-day activities
• Changes in personality, mood, or behaviour
• Difficulty thinking, problem-solving, or learning new information or language

When to see a doctor: Aging alone does not cause dementia, though it becomes more common with age. See a doctor if memory or thinking changes are new, getting worse, starting to affect daily life, or you are concerned about changes you are seeing.