Daytime sleepiness and Alzheimer's, best-practice care for children, intrauterine insemination and improving the diagnosis of mystery illnesses

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What is excessive daytime sleepiness and how is it linked to Alzheimer’s disease?

Dr. Norman Swan 0:00

Hello and welcome to this week's Health Report with me, Norman Swan. Today, a less traumatic alternative to in vitro fertilisation for couples having trouble conceiving. The quality of medical care for Australian children is falling short. A new way of diagnosing mystery illnesses, and sometimes you may not want to know the answer. And are you dropping off a lot during the day? Well, there are a lot of causes, but a recent study suggests there may be a link between what's called excessive daytime sleepiness and the physical changes in the brain which are associated with Alzheimer's disease. One of the researchers was Prashanthi Vemuri, who's Associate Professor of Radiology at the Mayo Clinic in Rochester, Minnesota, and I spoke to Prashanthi earlier.

Prashanthi Vemuri 0:39

Thank you for having me over.

Dr. Norman Swan 0:41

So what is excessive daytime sleepiness? How do we know if we've got it?

Prashanthi Vemuri 0:44

Excessive daytime sleepiness is generally difficulty in maintaining desired wakefulness and inability to stay awake during the day.

Dr. Norman Swan 0:53

So how do people with excessive daytime sleepiness sleep at night?

Prashanthi Vemuri 0:56

Excessive daytime sleepiness could be due to multiple different issues. It could be untreated sleep apnea. It could be because of insufficient sleep at night, a lot of stress, depression, due to which they have a difficulty staying awake during the day.

Dr. Norman Swan 1:11

So before you did your study, what was the evidence that there was any relationship at all between excessive daytime sleepiness and Alzheimer's disease or dementia, I should say?

Prashanthi Vemuri 1:21

We've always known that poor sleep is associated with increased risk of dementia. It's because sleep is really important for clearing toxins and beta amyloid in the brain.

Dr. Norman Swan 1:31

And I should just say beta amyloid is one of the chemicals that seems to build up in the brain in people with Alzheimer's disease, although its role in Alzheimer's disease is a little bit complicated and maybe controversial.

Prashanthi Vemuri 1:42

Yes, absolutely. But it's assumed to be one of the earliest hallmarks of Alzheimer's disease. And people with amyloid in their brain have increased risk of getting Alzheimer's disease.

Dr. Norman Swan 1:52

And of course, the problem here is that Alzheimer's disease causes sleep problems. It's like the depression story, which we've covered before. It used to be thought that depression caused dementia. But in fact, what's happening is when you've got early dementia, you tend to be depressed rather than there being a causal link. So presumably that's the conundrum with sleepiness as well.

Prashanthi Vemuri 2:11

Absolutely. You said it right, that sleep is necessary for clearing of toxins and beta amyloid. And beta amyloid also causes sleep disruptions.

Dr. Norman Swan 2:20

So you were trying to do the chicken and egg, horse and cart study?

Prashanthi Vemuri 2:24

Yes, absolutely.

Dr. Norman Swan 2:25

What did you do?

Prashanthi Vemuri 2:26

We identified about 300 people from our Mayo Clinic study of aging with an average age of 77. And we measured beta amyloid buildup in their brains over two years.

Dr. Norman Swan 2:37

So these are people that you've recruited in Olmstead County in Minnesota around the Mayo Clinic. And you've been watching them for several years and they started off really quite healthy.

Cindy Farquhar 2:46

Yes.

Dr. Norman Swan 2:47

Okay, so you followed them, you were doing scans of their brain looking for beta amyloid and you presumably were measuring the sleepiness.

Prashanthi Vemuri 2:53

Yes, we measured self-reported excessive daytime sleepiness at baseline. And we said the people who have excessive daytime sleepiness have increased amyloid over two years in order to actually attempt to answer the chicken and egg problem. So does baseline excessive daytime sleepiness predict future deposition of amyloid? And the answer was yes.

Dr. Norman Swan 3:14

How strong was that relationship?

Prashanthi Vemuri 3:16

I would say it was moderate. It was not extremely high because deposition of amyloid is a really slow process and it takes about 15 years to really build up to the levels of Alzheimer's disease. So given our short period of follow-up, which was two years, it was moderate.

Dr. Norman Swan 3:33

And were there any clinical signs of dementia or cognitive impairment in these people compared to people who didn't have excessive daytime sleepiness? No. So cause and effect is a really difficult thing to ascertain.