Urgent considerations
See Differentials for more details
Patients with altered mental status should be evaluated for conditions which can mimic dementia and require urgent treatment.
Patients with dementia who become agitated may require urgent management to prevent harm to themselves or others, or to alleviate severe distress.
Delirium
Delirium is an acute (hours to days), usually reversible, metabolically induced state of fluctuating consciousness. It involves rapid changes in the level of consciousness, and in level of orientation rather than a slow progression of memory and functioning as is found in dementia.
History or signs indicative of a general medical condition, such as infection, metabolic disturbance, or pharmacological toxicity, can sometimes be elucidated.[29]
If delirium is suspected, assessment should be based on the Diagnostic and Statistical Manual of Mental Disorders, 5th ed., text revision (DSM-5-TR) criteria or 4AT tool.[1][30] For critical care and post-surgical settings, the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) and Intensive Care Delirium Screening Checklist (ICDSC) are appropriate assessment tools.[30][31][32]
Initial tests to order include FBC, metabolic panel, fasting blood glucose, urinalysis, and urine culture. Further investigations and management are guided by clinical history and examination.
Herpes simplex virus encephalitis
Herpes simplex virus is the most commonly recognised single aetiology of sporadic encephalitis.[33] HSV encephalitis presents with acute onset of a febrile illness and altered mental status; typical features include headache, seizures, and focal neurological signs. A variety of cognitive deficits may persist after the acute stage, and they are often the sole cause of disability.[33] Aciclovir should be given in all cases of suspected viral encephalitis.
Wernicke's encephalopathy
Patients with acute thiamine deficiency may present with clinical features of Wernicke's encephalopathy (WE) including a subacute onset of the classic triad of ocular abnormalities, gait ataxia, and mental status changes. It is most commonly seen in nutritionally depleted people with a history of alcohol misuse. Mental status changes are the most constant component of the disease and include inability to concentrate, apathy, impaired awareness of the immediate situation, spatial disorientation, confusion, delirium, frank psychosis, and coma. It is important to recognise that the intoxicated patient who does not recover fully and spontaneously may have WE. Treatment with parenteral thiamine is indicated as soon as the disorder is suspected.[34]
Depression
Dementia and its relation to depression in older people requires particular attention, especially with regard to the accuracy of diagnosis. These two conditions can easily mimic each other. Dementia of depression (previously called pseudodementia) refers to reversible cognitive impairment seen in the setting of a depressive episode that improves with the treatment of that episode. Conversely, depression can be an early presenting symptom of dementia. It is unclear whether such an episode of depression is a prodrome for the onset of dementia, a risk factor for dementia, or an independent event. However, it appears most likely that the relationship between affective abnormality and cognitive decline is patient-dependent. Care must also be taken when making the proper diagnosis, as both the treatment and prognosis differ greatly between depression and dementia.[35]
Agitation
Agitation is common among individuals with dementia. It can occur at any time during the illness. Secondary causes of agitation among older adults must be ruled out, including underlying medical disorders, pain and drug effects. Initial management should include environmental and psychosocial interventions. Pharmacological interventions may be considered if these are unsuccessful.[9] Meta-analysis has demonstrated that risperidone is more effective than placebo at achieving 50% reduction in agitation after 8 weeks’ treatment.[36]
Antipsychotic drugs are associated with serious adverse effects and increased mortality in patients with dementia.[37] Therefore they should only be considered if symptoms are severe, are dangerous, and/or cause significant distress to the patient. The American Psychiatric Association and the National Institute for Health and Care Excellence have published guidelines on the use of antipsychotics to treat agitation or psychosis in dementia.[9][38] Treatment should be time-limited and regularly reviewed. No advantages in terms of efficacy or safety have been identified for any specific antipsychotic drug for the treatment of behavioural and psychological symptoms of dementia.[39] In order to avoid polypharmacy, antipsychotics that can be used safely by both the oral route and by injection are sometimes preferred. Initial doses of an antipsychotic should aim to achieve optimum benefit at the minimum possible dose.
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