Wednesday, May 27, 2009

Grow old gracefully to keep dementia at bay

Amusing. Below is a recitation of popular assertions about Alzheimer's. See here for my comments on the "growing old" study that he refers to. As is usual among journalists, he has ignored all the ifs and buts in the study concerned. His recommendations are a house built on sand. Yet the article comes from "The Times", of London, which makes it likely to be widely trusted

Working until you are 70 instead of 65 is one of the ways that you can minimise the risk of brain disease in later life. The Government is rumoured to be considering raising the retirement age to 70 in an attempt to reduce the national debt — plans that will have been given a useful fillip by new research that reveals postponing retirement can delay the onset of Alzheimer’s disease.

According to researchers from the Institute of Psychiatry, at the Maudsley Hospital, southeast London, every extra year worked delays the onset of dementia by just over a month. So working until you are 70 instead of 65 is likely to give you an extra six Alzheimer-free months. I am not sure that is enough of a benefit to warrant the additional effort, but extending your working life is not the only thing you can do to protect yourself.

One person in 20 over the age of 65 in the UK has some form of dementia. Alzheimer’s disease — characterised by a loss of brain cells, shrinkage and protein deposits forming tangles and plaques throughout the brain — may be the most common form, but it is not the only one. Gradual furring up of the arteries supplying the brain accounts for at least 20 per cent of cases and causes similar impairment to Alzheimer’s with resulting loss of memory and cognitive ability, disorientation and confusion. And, while there isn’t much we can do to slow the progression of Alzheimer’s disease, there is a lot that can be done to keep our brain and its circulation healthy — and the healthier your brain the less noticeable any deficit is going to be.

Use it or lose it. The brain is often compared to a muscle in that “exercising” it can slow the damage time brings, and challenging yourself mentally every day will help to keep you sharp. The latter can include hobbies, keeping up an active social life, learning new skills, doing crosswords and puzzles and brain-training games and, as the recent research has shown, working for longer.

The brain is made up of around 100 billion nerve cells, each connected to thousands of others through synapses and it is a decrease in this interconnectivity, rather than the loss of brain cells alone, that is responsible for the slowing of mental agility that occurs with advancing years. Challenging the brain is thought to help by maintaining existing synapses and encouraging the formation of new ones...

Check for diabetes. Ask the nurse at your doctor’s surgery for a blood test if you suspect diabetes — clues include a great thirst, peeing more than normal, recurring infections such as boils or thrush, lack of energy and blurred vision. Those most at risk include the overweight, anyone with a family history of the condition and those of Asian and Afro-Caribbean origin.

Drink in moderation. While sensible drinking — the equivalent of two or three small glasses of wine on most days for a woman and three to four for a man — can protect against some forms of dementia, heavy drinking has the opposite effect. One recent review suggests that alcohol accounts for at least 10 per cent of all UK dementia cases. You don’t have to be middle-aged or elderly to be at risk: there is evidence that heavy drinkers in their thirties and forties already have significant memory impairment.

Eat oily fish. Fresh tuna and tinned salmon, or fish oil capsules, may protect against Alzheimer’s disease and improve brain function. The exact mode of this protection is now under investigation, but it is thought that the omega-3 fatty acids in fish oils may slow the formation of plaques — an effect that may be enhanced by fatty acids also seeming to protect the delicate lining of the arteries supplying the brain, thus helping to maintain good blood flow. One American study found that men and women eating at least one portion of fish a week were half as likely to develop Alzheimer’s as those who didn’t eat any.

But the case is not so strong for another popular brain supplement. It is thought that as many as one person in ten with dementia is now taking ginkgo biloba despite the latest evidence, which suggests that, while the herb may boost blood supply to the brain, this doesn’t translate into any significant benefit.

Consider hormone replacement therapy (HRT). Women who take HRT have been shown in a number of studies to be less likely to develop Alzheimer’s disease later in life. But HRT has no impact on the progression of the disease once a woman develops the condition. Bottom line? It is a useful side benefit, but concerns about Alzheimer’s disease on their own are not a strong enough indication to prescribe HRT in women who are not having menopausal symptoms.


A Low-Carb Diet Can Hurt Your Memory

As a before-and-after study, this would seem to be well-controlled research

Low-carbohydrate diets are notoriously difficult to adhere to for long periods of time. Many of my patients have tried a low-carb diet and lost weight, some over 100 pounds, but most often the weight came back... and then some. Repeatedly gaining and losing weight (yo-yo dieting) can slow metabolism and pose risks to your overall health. Now, scientific studies are questioning whether these diets are dangerous to your brain's memory function, too.

Researchers at Tufts University have found that dieters who strive to eliminate most carbohydrates from their diets scored significantly lower on memory-based tasks than did subjects who simply reduced the amount of calories they ate.

The study subjects included 19 women ages 22 to 55, 9 of whom were put on a low-carbohydrate diet and 10 on a low-calorie but balanced diet. All subjects attended 5 memory-testing sessions in which their spatial memory, attention, cognitive skills, and short and long-term memory were assessed. These sessions were conducted throughout the 3 weeks of the study.

After 1 week of severe carbohydrate restriction, memory performance among the low-carb group, especially when dealing with difficult tasks, gradually decreased compared with the low-calorie group. In addition, the low-carb dieters had slower reaction times and faltered during tests of their visual-spatial memory.

The brain uses glucose as its main fuel but has no way of storing it for future use. The nerve cells use glucose immediately for energy, and if they cannot get this fuel, they aren't able to operate at peak capacity -- potentially leaving you feeling forgetful or unable to concentrate.

I read a study recently that found students and others who continually challenge their minds actually require more carbohydrates, and thus, seem to crave carbohydrate foods in direct proportion to how much they have to exert their brains. Perhaps carbohydrate cravings in such cases are the body's way of getting the brain the fuel it needs.

This study only tracked the dieters for 3 weeks and the study's sample size was small, but the authors suggest that, although low-carb diets can affect weight, they result in a lack of glucose to the brain that may be detrimental to learning, memory, and thinking.

According to the Tufts study, the popular low-carb diets—and particularly the "no-carb" diets—have the biggest potential for decreasing the ability to think and concentrate, and may also negatively affect overall mood. This could be one of the reasons many people have a hard time sticking with a no-carb meal plan.

Although carb-free diets may seem appealing, aim for at least a moderate amount of carbohydrate in your diet. In my weight-loss/nutrition practice at Johns Hopkins Bayview Medical Center, I refer to clinical research findings that suggest that for optimal function the human brain needs a minimum of 125 grams of carbohydrate each day.


1 comment:

Lena said...

I think we need better human biology education! Instead of teaching children that sugar is bad, they should be learning that your brain runs on glucose. It is like having a nice sports car and only putting in a litre of petrol at a time. You won't get far.

There is no evidence that consuming less sugar has any effect on diabetes incidence.