“In the next 30 years, the number of people with dementia is expected to triple. We need to do everything we can to reduce our risk of dementia.”

So stated the director-general of the World Health Organization (WHO), Dr Tedros Adhanom Ghebreyesus in May.

With that in mind, WHO produced a report listing the most important things we can do to stave off the condition. . .

Risk Reduction of Cognitive Decline and Dementia, WHO Guidelines, kicks off with an assertion we’ve been making for years: “[D]ementia is not a natural or inevitable consequence of aging. The existence of potentially modifiable risk factors means that prevention of dementia is possible…”

The authors carried out a comprehensive review of the published human studies on this topic. Most of them are observational studies – meaning they are not controlled trials that look at only one variable, such as alcohol consumption.

Instead, observational studies look at associations between different factors within populations. They ferret out statistical associations, e.g. “In a group of 100,000 people, those who were obese had an XX percent greater risk of dementia.”

But such studies can’t establish how obesity causes dementia, and they even leave open the door that some third factor associated with both obesity and dementia – such as high blood sugar – is the real cause.

The authors of the WHO report also took intervention studies into account. In these, one group is assigned to one type of treatment/activity, and another to a different type or to none. The groups are then compared. The authors did not consider most of these trials to be of a high enough standard, however, so outcomes are less dependable.

Because of the limitations of the evidence they examined, the authors classified only three of their recommendations as ‘strong’, out of 13 areas they looked at.

Physical Activity Tops the List

The first relates to physical activity, with the highest levels giving you the most protection against cognitive decline. Not only is physical activity directly beneficial to brain structures, but it also helps by reducing inflammation, supporting cardiovascular health, and boosting the immune system.

They strongly advise smokers to give up the habit. However, the authors had to admit that as far as safeguarding cognition is concerned, the quality of the evidence is low. But since it has so many health benefits, no downsides, and it might reduce the risk of cognitive decline, they believe it’s an important action to take.

Their final strong recommendation is to not take multi-complex nutritional supplements, vitamins B and E, and polyunsaturated fatty acids. Findings to support taking them are, in their view, “inconsistent.”

Why this appears in their top three is a mystery. The purpose of this report is to suggest actions people can take to lower their risk of dementia. Are the authors seriously suggesting that refraining from taking nutritional supplements reduces the risk of cognitive decline?

Stupid Things People Say about Supplements

Not to beat around the bush, this recommendation is nutty.  There exists a wealth of rigorous, placebo-controlled studies to support the benefits of vitamins and omega 3 fatty acids.

Meanwhile, large-population studies do NOT tell us much regarding supplement use, because they beg the question of what supplements all those thousands of people took, whether they faithfully took them every day, and for how many years they had been taking them. They also ignore interactions among supplements.

Worst of all, these large-population studies depend on the participants’ word for what supplements they took and how often.

Research on supplements suggests that most of the benefits go to those who take the full range of vitamins, minerals, and omega 3s, not to mention selected herbs and extracts such as resveratrol or PS. And I’m talking about taking them for decades.  The longer and more faithfully you’ve been supplementing, the better off you’ll be.

Now, I want to stress that a person who is really a walking nutritional disaster (and there are a lot of them out there) may get near-miraculous results if he or she starts taking, say, B12 after learning from their doctor they’re starting to get dementia.

But, to use an old-fashioned expression, “That’s no way to run a railroad.” For the most part, supplements are foods, not quick-fix pharmaceutical drugs.

Eat Mediterranean

Getting back to the more sensible ideas from the WHO report, they prefer to focus on food instead of supplements, and they encourage a Mediterranean-style diet. This guideline, like all the rest that follow, is a conditional recommendation.

This means — as far as cognition is concerned, and ignoring for the moment the other effects a food has on the body — the authors are not sure about the balance between desirable and undesirable outcomes. And they acknowledge that different choices might be appropriate for individuals according to their circumstances.

They accept that dietary factors are involved with the development of dementia and that “a healthy diet may have a great preventive potential for cognitive impairment.” Fruit, vegetables, nuts, olive oil, and coffee are most consistently associated with decreased dementia risk, they write.

The other conditional recommendations are to:

  • Stop drinking excessive amounts of alcohol
  • Challenge the brain with cognitive stimulation or training
  • Lose weight if overweight or obese
  • Reduce high blood pressure
  • Manage diabetes with medications or lifestyle interventions
  • Correct abnormal blood fats

The authors did not find sufficient evidence for taking antidepressants, wearing a hearing aid, or engaging in social activity. The studies they examined didn’t prove that these reduce the risk of cognitive decline or dementia, so they didn’t receive even a conditional recommendation.

Again, there are smaller, more rigorous studies to suggest that hearing loss, social isolation and medications are all strongly involved in causing people to lose memory and cognitive ability.

Overall Evidence is Weak

Perhaps the most important finding from the WHO report is how meager the existing evidence is for all these interventions, with the sole exception of physical activity. (By the way, I’m on record as calling exercise “the strongest medicine discovered so far for brain health.”)

For the other factors, Robert Howard, Professor of Old Age Psychiatry, University College London, summed up the problem when he said:

“These guidelines do an important job in highlighting the weakness of the available evidence and should be a call to arms for investment in the highest quality interventional dementia prevention trials.

“We are probably decades away from treatments to slow or stop established dementia. Prevention would be so much better than a distant cure.”

  1. https://apps.who.int/iris/bitstream/handle/10665/312180/9789241550543-eng.pdf?ua=1
  2. https://www.bbc.co.uk/news/articles/clldg965yzjo