October 19, 2018

expert reaction to review on the role of herpes in Alzheimer’s

Research published in Frontiers in Ageing Neuroscience shows the herpes virus may be linked to an increased risk of Alzheimer’s disease.

Prof Tara Spires-Jones, UK Dementia Research Institute Programme Lead, University of Edinburgh, said:

“This paper by Prof Ruth Itzhaki summarizes the scientific evidence for a potential role of herpes in increasing risk of developing Alzheimer’s disease.  This is a literature review and does not add new data to the field. The kind of studies discussed in this paper cannot determine whether the infection causes Alzheimer’s. The association between Alzheimer’s and herpes infections in the brain could be due to the damage to the blood brain barrier that occurs in Alzheimer’s which allow this common type of virus to infect the brain.”

Prof Clive Ballard, Medical School Pro-Vice-Chancellor and Executive Dean, University of Exeter Medical School, said:

“For many years the field was at a bit of an impasse with case control studies indicating an association between HSV (Herpes Simplex Virus) and Alzheimer’s.  Recently there have been two major steps forward in this area of research. First, an excellent study in Neuron showing a mechanistic link between HSV and processes important in Alzheimer’s disease. Second, a population based study in Taiwan, referenced in this review, demonstrating the association between dementia and HSV in a much larger group, but also highlighting the potential benefits of anti-viral therapy.”

Dr David Reynolds, Chief Scientific Officer at Alzheimer’s Research UK, said:

“This review article discusses previous research linking the herpes viruses to Alzheimer’s disease and as such, adds no new evidence to support a link between the two.

“Research into a link between the herpes virus and Alzheimer’s is so far very limited, with only a few scientists studying the association. This review presents mainly correlative studies that do not give clear evidence of cause and effect. The evidence presented in this review is not sufficient to suggest that Alzheimer’s disease is contagious and be passed from person to person like a virus and neither does it mean that having cold sores increases your risk of getting dementia.

“A growing body of evidence is linking the immune system with Alzheimer’s disease, and it’s important to explore the role that inflammation might play in the development and progression of the disease.”

Prof John Hardy FMedSci, Professor of Neuroscience, UCL, said:

“Dr Itzhaki has been ploughing a lonely furrow based on her belief that herpes infection is a risk factor for Alzheimer’s disease for a long time and most scientists, including me, have been sceptical.

“None of the evidence she cites is, on its own, convincing, but her work, and the recent work of others on the putative role of infections in disease, does suggest that this idea is worthy of some systematic study.  Certainly, there is clear evidence than there are direct links between inflammatory processes and Alzheimer’s disease”

Dr James Pickett, Head of Research at Alzheimer’s Society, said:

“Herpes is a hot topic in dementia research, as the infection appears to be more common in the brains of people with Alzheimer’s compared to healthy brains – but we don’t yet know enough about the relationship between the two.

“The link between herpes and dementia isn’t something that we feel people should worry about, although it’s sensible general advice to seek treatment for persistent cold sores. Dementia is not contagious and shouldn’t be thought of as an infectious disease.

“More research is needed to find out whether antiviral drugs can reduce dementia risk. Someone in the UK develops dementia every three minutes, and our scientists at the UK Dementia Research Institute are working hard to understand why, so that we can find ways to beat it.”

* ‘Corroboration of a major role for herpes simplex virus type 1 in Alzheimer’s disease’ by Ruth Itzhaki et al. was published in Frontiers in Ageing Neuroscience at 10:00am UK time on Friday 19th October.

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/tag/alzheimers/

Declared interests

Prof Tara Spires-Jones: No conflicts of interest.   

Dr David Reynolds: No conflicts of interest.

 Prof John Hardy: John is a member of the SMC Advisory Board Committee. No conflicts of interest.

Dr James Pickett: No conflicts of interest.

 None others received.