Can vaccines protect against dementia?

I had grown fond of an elderly patient who was living with dementia. Her family took such good care of her. Her hair was always nicely done, the grey strands glistening like silverware because of the copious petroleum jelly. Her neck, white as chalk, always seemed freshly dusted with a soothing scented powder. If I ever develop dementia, I hope this is how my loved ones will be there for me, with all the trials that will come at moments when I am nothing like my usual self, restless, unable to sleep, confused, and even hostile. Other days, I will be pleasant and lucid, greeting everyone politely.

WHAT IS DEMENTIA?

The World Health Organisation (WHO) describes dementia as a collection of signs and symptoms caused by different diseases that destroy the brain over time. There are about 10 million new cases of dementia annually worldwide. The effects include a breakdown in the ability to process one’s thoughts. Features of dementia include changes in mood, ability to control emotions and behaviour. The most common cause of dementia is Alzheimer’s disease, which results from a build-up of plaques or ‘coating’ on brain cells. Although there is no cure for dementia, a number of medications can help slow disease progression and improve quality of life. Persons are at increased risk for dementia when they are age 65 years or older, smoking, drinking too much alcohol, lacking regular exercise, overweight, or socially isolated.

Vaccine against shingles and its positive ‘side effect’ against dementia

A vaccine against shingles has been shown to decrease the risk of dementia by 20 per cent over a seven-year period. Researchers from Stanford University, USA, alongside collaborators from Germany and Austria suggest that “ the Zoster vaccine will be both far more effective as well as cost-effective in preventing or delaying dementia than existing pharmaceutical interventions.” A vaccine is usually designed to protect us from an infectious disease. Potential side effects of vaccines include pain, redness, and fever, or a more serious allergic reaction. Rare side effects include Guillain-Barré Syndrome (GBS), an excessive immune reaction that damages nerves and occurs at a rate of about one case per million persons vaccinated against flu, for example. GBS occurs more commonly after natural infection from viruses and bacteria than from vaccination.

The Stanford University researchers looked at electronic health records of over 280,000 persons in Wales to compare persons who received the vaccine against shingles and those who did not. The researchers were careful to demonstrate in their analyses that the protective effects seen were not because of better health-seeking behaviours in people who tend to get vaccinated, as health-seeking behaviours were similar between those who got the shingles vaccine and those who did not. Outside of shingles, the protection was specific to dementia, as no protective effect was demonstrated for the other ten leading causes of death in Wales.

EFFECTIVENESS OF THE SHINGLES VACCINE

‘Shingles’ or herpes zoster, caused by the same virus that causes chickenpox (the Varicella zoster virus), is common among the elderly, or persons with a weakened immune system. Shingles occurs as an itchy, burning or painful rash in a localised area of the body, and results from reactivation of the virus that stays dormant or quiet in the nerves. One in three persons who get chickenpox later develops shingles.

The shingles vaccine in this study is made from weakened live virus. The vaccine against chickenpox should not be given to someone to prevent shingles. Although the weakened virus used to make up both vaccines is the same, the amount of virus in the two vaccines is different. The 15-times higher amount of virus in the zoster vaccine makes it more effective in persons over age 50 years who have an ageing immune system. A newer shingles vaccine does not have the weakened live virus and is made of proteins resembling parts of the virus. This year the shingles vaccine became available in the private sector in Jamaica. The older shingles vaccine is about 50 per cent effective against shingles, compared to the newer vaccine that is over 90 per cent effective. The shingles vaccine can be given whether the person has had shingles before or not.

Dr Yohann White is a medical director at Para Caribe Consulting. Send feedback to columns@gleanerjm.com, yohann.white@caribewellness.com and @CaribeWellness on social media.