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Delirium or dementia and does it matter?

  • Jun 09 / 2021
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Current Affairs, David McMahon

Delirium or dementia and does it matter?

Delirium and dementia are both conditions which result in a persons altered conscious. Delirium is a short term and sudden onset (hours or days) disturbance in cognition, with usually treatable causes. It is often linked to infections such as chest infections, urine infections or dehydration. This contrasts with dementia which has a slow and insidious onset (several months to years) and sadly to date has no proven cure.

So why would it be important for both researchers and health professionals to not be confused themselves about why a patient is confused?

The truth is by being clear ourselves about what an aetiology or process is, we are creating a research environment with the correct nomenclature, discourse, and standards to meaningfully make contributions to research, and communicate with fellow researchers in the field. The ultimate aim being to push our knowledge of the processes and pathophysiology forward. This is a real and present need in both delirium research and dementia research[1] [2].

As part of my MD, I looked at how delirium and dementia are clinically assessed in real healthcare settings by reviewing the current international clinical practice guidelines (CPGs) on this.  To do this we performed a systematic review of the literature and had pre-defined criteria for data extraction which yielded our CPGs to analysis. The current field had a relatively small number of CPGs addressing these important topics, and many drew on expert opinion rather than higher standards of evidence for their recommendations to clinicians.

Apart from the intrinsic value that research itself has, and the duty of clinicians to improve upon, and offer the best care, there are also compelling demographic and socio-economic reasons which I’ll discuss below.

Person/patient benefits:

While it is true that there are no current cures available for dementia, it is nonetheless still worth identifying. Diagnosing the disease or risk of disease early is still valuable, as it means that the individual and their carers have time to make choices and plan for the future, and allows access to treatments that can help manage symptoms such as the pharmacological intervention for depression, or agents designed to retard the dementias progression  [7]. It can also enable vital support for their carers.

Specifically, the detection of delirium (an acute disturbance in cognition) on its own, or superimposed with the others, allows a treatable condition (i.e., infection), or iatrogenic effect to be addressed.  This is critical, as for every 48 hours of delirium that pass, there is an 11% increase in mortality. This also enhances the likelihood a person returning to their prior functioning [8].


There is a rising ageing population (i.e., those adults aged 65 years old and above) in Scotland, the rest of UK, and internationally [3]. This rise is fuelling escalating rates of dementia globally, in a linear fashion in high income countries and exponentially in low and middle income countries [4]. Equally, although delirium can affect anyone it primarily affects older patients [2].

Socio-health economics:

The costs to society, and not just to the person with dementia, is stark. The total estimated worldwide costs of dementia were US$604 billion in 2010. Roughly 70% of the costs occurred in western Europe and North America. Within high-income regions, costs of informal care and the direct costs of social care contribute similar proportions of total costs with direct medical costs accounting for a much smaller share. On the other hand, in low- and middle-income countries, informal care accounts for the majority of total costs with direct social care costs being negligible [5]. What these economic costs do not factor in is the huge human costs of caring for a relative or friend with dementia.

The same review went on to say that “Despite first being described more than 2500 years ago, delirium remains frequently unrecognised and poorly understood”. In 2011 delirium “affect[ed as many] as 50% of elderly people (i.e., those aged 65 years or older) in hospital, and cost more than US$164 billion per year in the USA and more than $182 billion per year in 18 European countries combined.”.  Again, the metrics are glaring – delirium presents a huge financial challenge to healthcare systems.

Methods and Results:

Given its importance in these conditions, clinicians look to guidelines to inform the care they offer which should be drawn from evidence-based medicine​ (i.e., research). Below details the methods we use to search the relevant literature and the quality score the results before combining those results into a synthesis:

The stacked polar chart shows which CPGs scored on which domains of the AGREE quality tool (generally Scottish & UK guidelines scored well, whereas the Royal College of Physicians CPG did not):

Results-AGREE scored CPGs:  

Below is  a table of all the guidelines – what they recommend to do, broken up by how to use the recommendations into 3 categories and the grade of the evidence used to make that recommendation i.e green high, yellow moderate and red poor quality CPG. This is presented for delirium in table 1 and for dementia in table 2.

Table 1: CPG synthesis for delirium


Table 2: CPG synthesis for dementia

– Answers to key clinical questions vague or not addressed
– Quality of evidence for recommendation predominantly expert opinion
– Discord between number dementia CPGs v importance of disease/prevalence & healthcare burden
– Limited geographic spread of dementia CPGs V delirium CPGs

Looking at the conclusions of our work, there are not many CPGs around how to assess cognition in dementia compared to delirium despite this huge global health burden; policy makers and public involvement in research priorities needed. There is a lack of primary research to base most recommendations on, and CPGs are not standard operating procedures for doctors to follow.    


1.  The search for a cure for dementia is not going well but behavioural changes can reduce the risk of developing it: The Economist; 2020 [cited 2021 18/05/2021]; Aug 29th 2020 edition:[Available from: https://www.economist.com/special-report/2020/08/27/the-search-for-a-cure-for-dementia-is-not-going-well

2.  Delirium is prevalent in older hospital inpatients and associated with adverse outcomes: results of a prospective multi-centre study on World Delirium Awareness Day. BMC medicine. 2019;17:1-11.

3.  Economic UNDo, Affairs S. World Population Prospects: The 2010 Revision, Volume II-Demographic Profiles. UN; 2013.

4.  Nichols E, Szoeke CE, Vollset SE, et al. Global, regional, and national burden of Alzheimer’s disease and other dementias, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. The Lancet Neurology. 2019;18(1):88-106.

5.  Wimo A, Jönsson L, Bond J, et al. The worldwide economic impact of dementia 2010. Alzheimers Dement. 2013 Jan;9(1):1-11.e3.

6. Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet. 2014 Mar 8;383(9920):911-22.

7. Rasmussen J, Langerman H. Alzheimer’s Disease – Why We Need Early Diagnosis. Degenerative neurological and neuromuscular disease. 2019;9:123-130.

8.  González M, Martínez G, Calderón J, et al. Impact of delirium on short-term mortality in elderly inpatients: a prospective cohort study. Psychosomatics. 2009 May-Jun;50(3):234-8.

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