Urinary tract infections can cause sudden confusion, known as delirium, in older people. But finding bacteria in someone’s urine does not necessarily explain their confusion, and the real cause may lie elsewhere.

An older person who was chatting normally at breakfast may, by the afternoon, not know where they are. They might be restless and distressed, unusually sleepy, or insist they can see someone who isn’t there. Families and care staff often reach for the same explanation: it must be a urine infection.

Sometimes it is. But the link between urinary tract infections (UTIs), which affect parts of the body such as the bladder or kidneys, and sudden confusion is complicated. Getting it wrong can mean missing the real problem.

Delirium is a sudden change in someone’s ability to concentrate, think clearly and understand their surroundings. It develops over hours or days, and symptoms can come and go: someone may seem alert one moment and muddled the next.

Some people become restless; others become unusually sleepy or withdrawn. This less obvious form, called “hypoactive delirium”, is easily missed.

Dementia, which affects abilities such as memory and thinking, usually develops over months or years. Someone who already has dementia can also develop delirium, becoming suddenly more confused than usual.

Delirium signals that something is interfering with how the brain works, often an illness or another physical problem. Older people and those with dementia or a serious illness are at increased........

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