A diagnosis of ‘dementia’ is not enough; the type of dementia influences the window for shared decision-making

A diagnosis of ‘dementia’ is not enough; the type of dementia influences the window for shared decision-making

Author: Professor Suzanne Timmons, Centre for Gerontology and Rehabilitation, University College Cork
Date of Publication: March 2022
Keywords: Dementia type, diagnosis, progression, anticipating symptoms, conversations, advanced care planning


When thinking about decision-making and planning care with and for a person living with advanced dementia, it may seem strange to think back to the time of diagnosis. But the reality is that things that happen around the time of diagnosis can have long-lasting effects, even to the end of life. We know that many people with dementia around the world are diagnosed too late, or never diagnosed.

Under diagnosis of dementia
Globally, dementia is undetected in 61.7% of people, most often in males, in younger people, and in ethnic minorities.1 In England, which had good baseline diagnostic rates, these declined over the Covid-19 pandemic.2

In Ireland, up to recently dementia was considerably underdiagnosed. Hospital-based studies, across 6 different hospitals in Cork city and county initially, and then in 1 hospital in Dublin, and more recently in 1 hospital in Sligo, all had remarkably similar results. These studies showed that only 36-40% of older people admitted to hospital with a diagnosis of dementia made by a research team, based on cognitive testing and collateral history, were previously known to have dementia.3-5 In the Cork study, some people first diagnosed as part of the study had moderate and even severe dementia.3

Consequences of late diagnosis
Unfortunately, not receiving a formal diagnosis, or receiving this too late, negatively impacts the person’s chance to discuss their priorities and values and to make plans for their future care. Thus, it is crucial that countries invest in the resources to ensure that everyone with dementia gets the opportunity for a timely diagnosis.

Developments in dementia diagnosis in the Republic of Ireland
In Ireland, there has been recent funding for more diagnostic services, through Memory Assessment Support Services, which can diagnose moderate complexity dementia, and through Regional Specialist Memory clinics, who have the capacity to diagnose highly complex dementia, such as where the person is younger, or has an underlying intellectual disability, or has a pre-existing neurological or other condition that impairs communication.

A forthcoming model of care (National Dementia Office, 2022) will outline the number of these services required at population level, and the staffing level and skill mix required, noting that population ageing will require increased capacity year on year to keep up with increased demand in both the Republic of Ireland and Northern Ireland (Sheehan, and O’Sullivan, 2020, p.5).

The importance of diagnosing dementia and its type
This brings us to a closely related issue. As we know, there are hundreds of different diseases that cause dementia, with about 5-6 being “common”. Being diagnosed with dementia is first step to accessing post-diagnostic information, advice, and support services, assuming these are available locally. However, being diagnosed with ‘dementia’ is not enough. The type of dementia, such as Alzheimer’s disease, or dementia with Lewy bodies, or frontotemporal dementia, profoundly influences the person’s experience of having dementia and the immediate health and social care support services they need to access.

For example, a person living with Alzheimer-type dementia would typically have early cognitive and psychological symptoms, but not particularly physical symptoms such as physical pain, difficulties with breathing, or issues with balance, until advanced dementia. In contrast, a person with dementia with Lewy bodies would usually have physical symptoms early in the course of the dementia, including falls, which could cause fracture, contracture, pressure ulcers, etc, all causing pain, or swallowing difficulties, which might lead to aspiration pneumonia and hence pain, dyspnoea, anxiety. Decisions about feeding and hydration might need to take place much earlier for this person than someone with Alzheimer-type dementia.

Moreover, the dementia type may affect a person’s ability to take part in conversations about their current care and to make decisions about future care. A person with language-variant frontotemporal dementia may lose their ability to communicate very early in their dementia course, while a person with behavioural-variant frontotemporal dementia may have impaired executive function early on, and thus struggle to make decisions and weigh up risks.

Finally, some types of dementia have a more rapid progression than others, so a person may more quickly develop symptoms and features that are common in advanced dementia (pain, dyspnoea, sarcopenia, seizures, etc.) Again, for this person, conversations about future care need to take place sooner rather than later. Thus, in order to prioritise conversations around future care, both in terms of their timing and anticipating likely future symptoms and complications, it is necessary to know the type of dementia.

Maximising the opportunity for shared decision making
While many people with dementia don’t want to focus too much on the future in very early dementia, preferring instead to focus on living life to the full in the current time, it is important that the clinician and the person knows that the window for shared decision-making and conversations about the future is more limited for some people.

This means that diagnosis needs to be made by a competent team, using adequate clinical assessment, and having access to supporting tests as required, such as brain imaging and cerebrospinal fluid analysis.

Currently in the republic of Ireland, there is insufficient access to timely neuroimaging such as Magnetic Resonance Imaging, and more so for advanced neuroimaging such as biomarker imaging studies. This can impede an accurate and timely diagnosis of the type of dementia.

To conclude, as well as improving decision-making around care in advanced dementia, let’s not forget to continue to advocate for timely and accurate diagnosis, not just of dementia, but of the type of dementia. This gives the person the best chance of taking part in decision-making in a timely manner, focussed on their likely future symptoms.

In an ideal world, research such as mySupport study would supplement prior conversations with the person living with dementia about their priorities and values, their concerns for the future, and their choices for care in advanced dementia.

To learn more about mySupport study watch this 3-minute video. Click on the language of your choice: English | Italian | Czech | Dutch | French Canadian


  1. Lang L, Clifford A, Wei L, et al (2017). Prevalence and determinants of undetected dementia in the community: a systematic literature review and a meta-analysis. BMJ Open 7: e011146.
  2. NHS Digital Dementia 65+ estimated diagnosis rate indicator. Available at: https://digital.nhs.uk/data-and-information/data-tools-and-services/data-services/general-practice-data-hub/dementia-diagnosis-rate-and-prescription-of-antipsychotic-medication-to-people-with-dementia. Accessed May 4th 2021 (includes data to 30th April 2021).
  3. Timmons S, Manning E, Barrett A, et al (2015). Dementia in older people admitted to hospital: a regional multi-hospital observational study of prevalence, associations and case recognition. Age and ageing. ;44(6):993-9.
  4. Briggs R, Dyer A, Nabeel S, et al. Dementia in the acute hospital: the prevalence and clinical outcomes of acutely unwell patients with dementia, QJM: An International Journal of Medicine, Volume 110, Issue 1, January 2017, Pages 33–37, https://doi.org/10.1093/qjmed/hcw114
  5. Dolan C, Mohd Zubir M, Melvin V, et al (2021). Delirium occurrence in older Irish adults admitted to an acute medical hospital: A prospective cohort study. Irish Journal of Psychological Medicine, 1-9. doi:10.1017/ipm.2020.133
  6. National Dementia Office. Model of Care for Dementia in Ireland (Draft for Public Consultation, August 2021)
    https://dementiapathways.ie/care-pathways/draft-model-of-care-for-dementia-in-ireland. Accessed Jan 2022.
  7. Sheehan A and O’Sullivan R (2020). Ageing and Public Health – an overview of key statistics in Ireland and Northern Ireland. Dublin: Institute of Public Health.

Meet the author:

Professor Suzanne Timmons qualified from University College Cork and trained in Ireland, the UK and the US. She is a geriatrician and works 50% clinically, in the acute hospital setting and in rehabilitation. She was the first Clinical Lead for Dementia for the Republic of Ireland, from 2017 to 2021. In UCC, she is based in the Centre for Gerontology and Rehabilitation, School of Medicine.

Her academic commitments include being Programme Director for the MSc in Older Person Rehabilitation and the MSc in Dementia, as well as the supervision of research MSc and doctoral students. She has a keen interest in postgraduate interdisciplinary education and research. Her research interests focus on neurodegenerative disease in older people, particularly dementia and Parkinson’s disease, spanning basic science translation, diagnostic tool validation, health service research (especially models of care), clinical trials, technology in rehab, exercise and risk reduction.