Dementia epidemiology

Neurodegenerative conditions are predicted by the World Health Organisation (WHO) to become the world’s leading cause of death by 2040. This class of disease constitutes a group of progressively debilitating conditions with unique disease-specific profiles, characterised by the selective loss of distinctive neuronal groups.

What is dementia?

Neurodegenerative dementias represent a class of pathologies that have varying degrees of, but unarguably, the progressive decline in cognitive functions such that there is interference in an individual’s ability to perform everyday duties, impacting on their social function and/or their capacity to perform usual occupational tasks.

Types of dementia

The most common forms of dementia include Alzheimer’s disease (AD), Lewy body dementia (DLB), frontotemporal dementia (FTD) and vascular dementia. Both AD and DLB continue to be the leading cause of degenerative dementia in the elderly population (Figure 1).

Figure 1 – Dementia subtypes and prevalence

Representative data from the Alzheimer’s society’s (UK) envisaged proportions of the subtypes of dementia and their prevalence in the UK alone. Adapted from (, published September 2014.

Dementia epidemiology

Dementia has emerged as an epidemic with aging being the predominant risk factor. By 2050, the number of people aged ≥60 years will have increased by 1.25 billion, accounting for approximately 22% of the total global population, with 79% living in less developed regions. Whilst the observed and projected increase in the number of people affected by dementia has largely been explained by the increase in population longevity, specifically in the developing world, dementia per seis not a natural part of the aging process.

Those affected by neurodegenerative dementias are principally aged 65 years and over with early-onset dementia accounting for only 2-5% of all cases, furthermore the prevalence nearly doubles with every additional 5 years of age following the age of 65 underscoring an increase in an age-related risk of developing neurodegeneration, in parallel with an increase in longevity.

In 2015 WHO reported 47.5 million people were afflicted worldwide by dementia, increasing from 35.6 million people in 2012 (WHO April 2012) and cases are predicted to rise by 7.7 million each year. It has been forecast that by 2050 the worldwide prevalence of dementia will reach 137.5 million. In the UK alone, 850,000 people are affected, this bestows a substantial burden on the economy with the cost of health care in the region of £26 billion, annually.

The broad-spectrum of dementia produces a gender bias with a predisposition towards females, 61% of dementia cases are seen in the female population when compared to 39% of males. This is a consistent observation that could be explained by the protracted longevity in females when compared to males. 

Global distribution of dementia

A systematic review contemplates the global prevalence of dementia and identifies a higher incidence in Latin-America and lowest in Sub-Saharan Africa with the greater proportion of dementia cases, being affiliated with low-middle range incomes. To corroborate this, more recent population-based studies on “high-income” countries have contradicted previous projections regarding dementia prevalence, indicating a decline in the age-associated risk of dementia. This has been attributed to various factors, largely surrounding the fact that higher levels of education and advances in treatment and diagnostics may lead to the early intervention of dementia indicators; these include cardiovascular risk factors such as obesity and diabetes. A recent UK based study on dementia has reported a 20% decrease in dementia incidence over the last two decades in males. If the previous projections are proving variable, then it is possible that the predicted figures may be regionally modulated in accordance with the scope of social health care support available and attainable by the general population.


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McKeith, I.G., et al., Diagnosis and management of dementia with Lewy bodies: third report of the DLB Consortium. Neurology, 2005. 65(12): p. 1863-72.

Sousa, R.M., et al., Contribution of chronic diseases to disability in elderly people in countries with low and middle incomes: a 10/66 Dementia Research Group population-based survey. Lancet, 2009. 374(9704): p. 1821-1830.

van der Flier, W.M. and P. Scheltens, Epidemiology and risk factors of dementia. Journal of Neurology, Neurosurgery & Psychiatry, 2005. 76(suppl 5): p. v2.

Prince, M., et al., The global prevalence of dementia: a systematic review and metaanalysis. Alzheimers Dement, 2013. 9(1): p. 63-75.e2.

Langa, K.M., Is the risk of Alzheimer’s disease and dementia declining? Alzheimer’s Research & Therapy, 2015. 7(1): p. 34.

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Matthews, F.E., et al., A two decade dementia incidence comparison from the Cognitive Function and Ageing Studies I and II. 2016. 7: p. 11398.

Introducing the Coronavirus

In December 2019, a new virus emerged that was named coronavirus 2019 (COVID-19) by the World Health Organisation (WHO) in February. The virus has been classified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is preceded by two other coronaviruses: severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). The knowledge collected from previous outbreaks along with data collection for COVID-19 will continue to provide sources of information for vaccination/drug development.

What is a coronavirus?

Coronaviruses are approximately 120 nm in diameter and are enveloped [1]. The virus particles contain strands of RNA – RNA gives the instructions for making proteins. For the viruses, these strands provide all the information needed to make multiple copies of themselves, including the spikes on the surface of the virus, the envelope, nucleocapsid that houses the RNA and the viral membrane. In order to do this, they need to gain entry into our cells and once inside our cell, they will hijack our own cellular machinery so they can make proteins from their RNA molecule and build more viruses.

How does coronavirus spread?

In order to make copies of itself, the virus needs to find a way to enter a host’s cell. It can do this by attaching itself to molecules on the cell surface of cells in the lungs. Scientists in China have shown that in the case of COVID-19 (and SARS) the virus binds to angiotensin-converting enzyme II (ACE2) which acts as a receptor [2] for the spikes on the viral envelope. From here it gains entry into the cytoplasm of the cell, and will access the machinery to replicate itself. Once the virus has replicated itself, its particles are released from the cells, and this is where coughing, for example, will release these new particles from the lungs into the air in droplets, ready to be picked up by a new unsuspecting host.

Why is there not a cure?

When a new infection occurs that has not been seen before, the immune system will not be prepared to fight it. This is the same with any new disease, whether viral or bacterial. Targeting the virus means getting to know everything about it before a cure can be found and even then, it takes months or years to develop a vaccine. WHO is presently working with Chinese scientists to get over 80 clinical trials up and running so the pressure is on and I have no doubt, everything that can be done, is being done.


1.            Li, X., et al., Molecular immune pathogenesis and diagnosis of COVID-19. Journal of Pharmaceutical Analysis, 2020.

2.            Zhou, P., et al., A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature, 2020. 579 (7798): p. 270-273.

Scientific Writing

What is scientific writing

Scientific writing is an essential part of science with the documentation of ideas and demonstrable evidence of findings from qualitative and quantitative studies. How we gather, process and then communicate information is changing at the same time as technology is evolving, providing more platforms for scientific knowledge to be shared. This information needs to be delivered in a manner that is appropriate for its audience, thus, enabling its distribution and interpretation accordingly.

Styles of scientific writing

Scientific writing may be in a technical format, for example, the reporting of scientific observations and findings as a result of a study or notes in a lab book including methodology, research ideas and results. Conversely, scientific writing may include conveying information in a non-technical manner for a wider audience, for example, those that do not work in the science industry

Technical scientific writing

This is an example from a paper I published, written specifically for a scientific audience:

Non-technical scientific writing

Delivering complex scientific information to a non-scientific audience can be a difficult task and requires the breaking down of the information into bite-size and understandable chunks. Taking an extract from the example above, it has been re-written for a non-scientific audience:


‘Dementia with Lewy bodies (DLB) is the second most prevalent neurodegenerative dementia, where an accumulation of aggregated fibrillar alpha-synuclein in neurons of limbic and forebrain regions of the brain leads to visual hallucination, cognitive impairment of a fluctuating nature and extrapyramidal motor disturbances. Beta-synuclein counteracts aggregation of alpha-synuclein in vitro and in animal models; however, it is not clear whether this effect occurs in human Lewy body dementia (LBD) diseases.’


Dementia with Lewy bodies (DLB) is a common form of dementia caused by gradual loss of brain cells. The cells affected are in the cortex and regions involved in memory. DLB sees protein aggregates formed from the sticking together of proteins into clumps inside the cells; the loss of these brain cells leads to the changes that characterise dementia such as memory loss, behavioural and personality changes. Beta synuclein and alpha-synuclein are proteins in the brain; alpha-synuclein is found in the protein aggregates – called Lewy bodies and beta-synuclein is a similar protein that can prevent the aggregation of alpha-synuclein. It is not known whether this effect is seen in humans also.’

Essentially, the pitch of the writing will be appropriate to those that will be reading it; however, it is imperative, when conveying such information that the information is interpreted correctly before disseminating.

Tracey Evans Writing Services

To conclude, be aware of the audience and write the piece accordingly. Scientific writing can be fun and light-hearted, journalistic or formal. If you would like some help with scientific writing please contact me.