Difference Between Delirium and Dementia

Delirium and dementia are two old age disorders. With old age, gradual loss or impairment of cognitive abilities is a natural phenomenon. However, when there are improper and often abnormal changes in thinking and behavior they may be indicative of an underlying disease or ailment. Delirium and dementia are two ailments that have many similarities and often spoken of in interchangeable manner though they are separate and different diseases. This article will highlight the differences between delirium and dementia by bringing out their features so as to enable readers to find out what they are their close ones are suffering from.

Abnormal changes in a person’s behavior and thinking are often indicative of physiological changes taking place inside the brain. There may be events in life that have deep impact on the higher functions of brain directly affecting a person’s thinking, memory, outlook and interaction with others and environment.


This is a term that refers to an umbrella of symptoms associated with a cluster of underlying disorders rather than being a disease in itself. When a person suffers from delirium, he is said to be in an acute state of confusion. The onset of delirium is due to many reasons such as addiction to alcohol, drug abuse, dehydration, medication side effects or any other reason. The person becomes hyperactive, hallucinates and becomes difficult to calm down. However, there are cases of delirium where the person can be drowsy, lethargic, and unable to follow instructions. Delirium usually occurs in very old age and the patient is confused about himself as well as those surrounding him. If a person has delirium symptoms in hospital settings where he is getting medication and care, it is necessary to diagnose the underlying causes or it becomes fatal. If diagnosed properly, it is possible to provide relief from symptoms of delirium.


Dementia refers to loss or impairment in cognitive abilities, particularly of memory and the ability of a person to perform a task in correct motor sequence. Patient also experiences difficulty in speech and understanding what others are saying. His sentences become incoherent and he cannot speak in a right manner. Dementia is also a cluster of symptoms and can have many underlying reasons. The most common cause of onset of dementia is Alzheimer’s disease in the country which has increased alarmingly in the last few decades.

Talking of differences,

• While dementia causes a change in a person’s behavior and thinking in a slow and gradual manner that takes years to show up, delirium causes sudden onset of symptoms that are characterized by hallucination and incoherent speech that is easily recognizable.

• While delirium is curable and reversible, dementia is progressive and often incurable.

• While delirium lasts for days to weeks, dementia is permanent in nature.

• The person is hyper alert in delirium, while in dementia the patient shows little change in condition until the condition becomes worse.

• Ability to focus is greatly reduced in delirium while a person can concentrate in dementia