Category: Dementia

Alzheimer’s causes degeneration in part of the brain that controls this function first.

Excessive napping during the day can be an early sign of Alzheimer’s, the most common form of dementia.

Scientist tended to assume that people with Alzheimer’s disease are drowsy during the day because of poor sleep at night.

Research has now shown, though, that it is due to the degeneration of neurons that maintain wakefulness.

The tau protein, one of two proteins involved in Alzheimer’s, is responsible for the critical neurodegeneration.

Alzheimer’s causes degeneration in this part of the brain first, which is why daytime napping without night time sleep problems is an early sign of dementia.

Professor Lea T. Grinberg, study co-author, said:

“We were able to prove what our previous research had been pointing to—that in Alzheimer’s patients who need to nap all the time, the disease has damaged the neurons that keep them awake.

It’s not that these patients are tired during the day because they didn’t sleep at night.

It’s that the system in their brain that would keep them awake is gone.”

Many of the key neurons are in the hypothalamus, a part of the brain that is central for wakefulness and arousal.

These neurons are so important as they affect a large number of other critical nerve cells.

Mr Joseph Oh, the study’s first author, explained:

“You can think of this system as a switch with wake-promoting neurons and sleep-promoting neurons, each tied to neurons controlling circadian rhythms.

It’s a small number of neurons but their computational capabilities are incredible.

When these cells are affected by disease, it can have a huge effect on sleep.”

The conclusions come from a study of 33 patients with Alzheimer’s that were compared to normal controls.

Dementia and sleep

Many other studies have found a link between dementia and sleep.

People who sleep for too little or too long are at a higher risk of cognitive decline and dementia.

Indeed, people who sleep more than 9 hours a night have double the risk of developing dementia, one study found.

However, those who sleep for between 5.5 and 7.5 hours per night do not see declines in their cognitive health, even when suffering the early effects of Alzheimer’s disease.

Those sleeping longer also have lower brain volumes.

Also, getting less REM sleep — the phase in which we dream — is linked to dementia.

During sleep the brain cycles between periods of deep sleep and then up towards shallower periods of sleep in which we tend to dream, whether we remember those dreams or not.

During REM sleep the eyes move rapidly from side-to-side (hence Rapid Eye Movement Sleep).

The study was published in JAMA Neurology (Oh et al., 2022).

Risk of developing dementia is one-third lower.

Memory often worsens with age — it is a normal part of the aging process.

But, when do mild memory problems signal the onset of Alzheimer’s?

Ironically, people who realise their memory is getting worse are less likely to develop Alzheimer’s disease, research finds.

Self-awareness, then, is a healthy sign.

Doctors have long suspected that people who seem unaware of their memory problems are at higher risk of dementia, but this is one of the first studies to demonstrate it.

Researchers at McGill University in Montreal, Canada, looked at data from 450 patients experiencing mild memory deficits.

The patients’ experience of their own memory was compared with the objective views of friends and family.

Patients unaware of their memory problems turned out to be in worse shape neurologically: they had metabolic dysfunction in their brains and more amyloid proteins (these are linked to Alzheimer’s).

Two years later, patients who were more unaware of their memory problems were at triple the risk of developing dementia.

Dr Serge Gauthier, study co-author, said:

“This has practical applications for clinicians: people with mild memory complaints should have an assessment that takes into account information gathered from reliable informants, such as family members or close friends.”

The study was published in the journal Neurology (Therriault et al., 2018).

The results are based on a review of over 70 different studies.

Vitamin D probably does not help protect people from dementia or other brain-related disorders, research finds.

While vitamin D is essential for the body, there is no solid clinical evidence that it benefits brain health.

Ms Krystal Iacopetta, the study’s first author, said:

“Our work counters an emerging belief held in some quarters suggesting that higher levels of vitamin D can impact positively on brain health.”

The results are based on a review of over 70 different studies.

There was no evidence vitamin D protected against Alzheimer’s, Parkinson’s or other brain diseases.

Ms Iacopetta said:

“Past studies had found that patients with a neurodegenerative disease tended to have lower levels of vitamin D compared to healthy members of the population.

This led to the hypothesis that increasing vitamin D levels, either through more UV and sun exposure or by taking vitamin D supplements, could potentially have a positive impact.

A widely held community belief is that these supplements could reduce the risk of developing brain-related disorders or limit their progression.

The results of our in-depth review and an analysis of all the scientific literature however, indicates that this is not the case and that there is no convincing evidence supporting vitamin D as a protective agent for the brain.”

However, there may be evidence that sunlight is good for the brain.

Professor Mark Hutchinson, study co-author, explained:

“We have presented critical evidence that UV light may impact molecular processes in the brain in a manner that has absolutely nothing to do with vitamin D.

It may be that sensible and safe sun exposure is good for the brain and that there are new and exciting factors at play that we have yet to identify and measure.

Unfortunately however, it appears as if vitamin D, although essential for healthy living, is not going to be the miracle ‘sunshine tablet’ solution for brain-disorders that some were actively hoping for.”

The study was published in the journal Nutritional Neuroscience (Iacopetta et al., 2018).