Dementia and Delirium



The term ‘organic mental disorder/syndrome’ in psychiatry is used when there is a ‘disease of the body’ which present with psychiatric symptoms. In contrast, ‘functional mental disorders’ are considered to be ‘disease of the mind’. Classifying psychiatric disorders in this way is becoming outdated now that more is known about the ‘organic’ basis of functional illnesses, such as abnormal brain structure in schizophrenia. However, the term organic is still commonly used in clinical practice and communication and is included in the ICD 10.

In the next section we will focus on two ‘organic disorders’ which effect cognitive function. Other organic disorders for example:

Organic hallucinosis Organic delusional disorders Organic mood disorders Organic anxiety disorders will not be mentioned here, as they present almost similar to their ‘functional’ counterpart.


Delirium and Dementia:

In both delirium and dementia, there is a generalized impairment of brain function which causes global impairment in cognitive function and altered mood and behaviour. The difference between the two is that delirium is an acute syndrome characterized by fluctuating levels of consciousness and attention whereas dementia is a chronic syndrome which occurs in clear consciousness without rapid fluctuations. Both conditions are more common in older people, but the diagnoses need to be considered in any patient who presents with a generalized impairment of brain function.


  1. Delirium:

Delirium is more likely to occur in children, the elderly and individuals with brain insult when the brain ‘vulnerable’. People with dementia are particularly at risk and so it is always important to rule out superimposed delirium if the cognitive function of people with dementia deteriorates acutely. Another high risk group are people admitted to medical ward-studies have found 15-50% evidence of delirium.

The features of delirium will be summarized and contrasted with typical symptoms of dementia in a table below.


Management of delirium:

The primary goal is to investigate and treat the underlying cause. Some causes of delirium are:

Medications and drugs: Anticholinergic, anticonvulsant, anxiolytic, digoxin, corticosteroids, Alcohol , solvents, illicit drugs Infection Endocrine: hypoglycemia, hyperparathyroidism, Addison’s disease, thyroid disease. Metabolic: electrolyte imbalance, hypoxia, organ failure, vitamins deficiency (esp. thiamine), prophyria. Neurological: infection such as encephalitis or meningitis, raised intracranial pressure, space occupying lesions, head injury, epilepsy.

While trying to find the primary underlying cause, it will be necessary to manage the patient symptomatically.

Ø The patient should be nursed in a well lit room by as few people as possible, in order to reduce confusion. Ø Sedation with low doses of antipsychotic drugs may be required (prescriber should have knowledge about the prescribed medication( its side effect, its metabolism, half-life, dosage etc) Ø Orient the patient by gently calming them down and use cues to indicate time of day (window, clock). Avoid excessive ‘reminders’ if this cause patient’s distress.

  1. Dementia:

Dementia is a chronic usually progressive generalized impairment of the brain function. The risk increase with age: 5% >65 and 20% >80

Typical symptoms of dementia include:

Memory (amnesia): is virtually always affected, with short term-memory and memory for recent events being lost first. Memory of events from the distant past is usually preserved until the very late stages of the illness. Orientation in time and place: are lost relatively early in the illness which may result in the person becoming lost and wandering aimlessly. In the later stages of the illness, orientation in person may be lost with the person not recognizing familiar people or themselves. Praxis: the ability to coordinate complex motor function is affected. The person may not be able to perform acts on command but still perform spontaneously., or may be unable to carry out a sequence of tasks despite being able to perform each task individually. Language function (Dysphasia): is impaired, initially with finding words(nominal dysphasia or anomia), progressing to difficulties generating speech (expressive dysphasia), comprehending speech (receptive dysphasia) or combination of the two (mixed dysphasia). Abstract thinking and judgment: are impaired, leaving the person unable to deal with problems or unfamiliar situations. Personality changes: are common, often involving a coarsening of pre-existing personality traits. Social behaviour: deteriorates, often becoming shallow or inappropriate. Mood changes: are common with depression irritability and anxiety all occurring in some cases

The above are just some of the symptoms and the presentation will depend largely on the cause and type of dementia. It is important to attempt to establish the type of dementia as this will influence treatment and prognosis. The four commonest causes are:

Alzheimer’s disease, Vascular dementia, Mixed dementia (usually vascular & Alzheimer’s) and Lewy body dementia

Other causes and types:

Degenerative: Parkinson’s dementia, Huntington’s dementia, Pick’s disease, Normal pressure hydrocephalus Infections: Creutzfeld-Jacob Disease (CJD), HIV, Neurosyphilis, cerebral abscess, UTI Space-occupying lesions: tumors, subdural hematoma Traumatic: severe head injury, boxing Endocrine: hypothyroidism, Cushing’s disease, hypopituitarism Metabolic: anemia, hypoxia, organ failure Toxic: heavy metals (lead, mercury, iron), chronic alcohol abuse (alcohol dementia), medication with anticholinergic propensity. Autoimmune: SLE, sarcoidosis.

The above list (like in delirium) is short and by no means extensive as the causes are many and the above are only a short examples ( think common sense: any insult to the brain can cause you to have any number of psychiatric symptoms be it dementia, psychosis, depression or any other)

Management of dementia:

Ø History & mental state examination: as the patient with dementia is often unable to give a full account of their problems, an informant presence is important. Scales such as the Mini-Mental State Examination (MMSE) are useful screening tests and quick to administer. Much detailed scales and psychological testing may be needed to confirm or establish the diagnosis. Ø Physical examination & investigations: are important to establish cause and therefore treatment (reversible or irreversible). Ø Medications: the current drugs can be divided into two groups. First the drugs which increase acetylcholine (Aricept, Galantamine). The second group is the works through receptors affecting GABA (Memantine). Both groups are licensed for Alzheimer’s, but in practice are worth trying in the most of the dementias. The clinical effect appears after months and monitoring done by history taking and MMSE score. Antidepressants may be useful, as well as antipsychotic (but due to anticholinergic side effect, they showed be used by a person aware of their advantages and disadvantages). Ø Psychological & social treatment: simple behavioural techniques such as prompts can be useful for mild memory impairments. Revalidation and reminiscent therapy also could be tried. Social support especially for carer is extremely important and is one of the major management targets

Features of delirium and dementia (comparison):

In the next table a simplified approach comparing delirium vs. dementia (remember that the two can co-exist esp. in the elderly)





Acute, usually within hours or days

Gradual, usually within months

Diurnal variation

Yes, usually worse at night

Maybe worse at night


Days or weeks, usually less than 6 month

Months or years


Drowsy or hypervigilant



Usually poor

Usually maintained


Disoriented in time, often place and person

Disorientation usually in time then place, in person much later

Instant recall


Usually intact until late


Impaired STM & LTM

Impaired STM, LTM much later


Muddled, confused

Reduced, slow



Less common


Common usually visual

Only in later stages


Reversal of sleep-wake cycle


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