Tag Archives: Alzheimer

“Diabetes of the brain”

5 Aug

The idea that Alzheimer’s disease might be a kind of diabetes has been floating around the research community for a number of years. Now it’s beginning to garner some media attention. Here is a 2008 paper that explains the hypothesis:

‘For nearly three decades of relatively intense research on AD, the inability to interlink this constellation of abnormalities under a single primary pathogenic mechanism resulted in the emergence and propagation of various heavily debated theories, each of which focused on how one particular component of AD could trigger a cascade that contributes to the development of all other known abnormalities. However, reevaluation of the older literature revealed that impairments in cerebral glucose utilization and energy metabolism represent very early abnormalities that precede or accompany the initial stages of cognitive impairment1 and led us to the concept that impaired insulin signaling has an important role in the pathogenesis of AD and the proposal that AD represents “type 3 diabetes.”’

This suggests that the behaviors that protect against diabetes may also protect Alzheimer’s disease.

 

 

Yoga may reduce mild cognitive impairment

27 Jul

Let me state my biases right upfront, I am a yoga practitioner, so I may have a tendency to be less critical of yoga positive research. With that in mind, let me report on this study published in The Journal of Alzheimer’s Disease: “Changes in Neural Connectivity and Memory Following a Yoga Intervention for Older Adults: A Pilot Study.” Here is the abstract:

BACKGROUND:
No study has explored the effect of yoga on cognitive decline and resting-state functional connectivity.

OBJECTIVES:
This study explored the relationship between performance on memory tests and resting-state functional connectivity before and after a yoga intervention versus active control for subjects with mild cognitive impairment (MCI).

METHODS:
Participants ( ≥ 55 y) with MCI were randomized to receive a yoga intervention or active “gold-standard” control (i.e., memory enhancement training (MET)) for 12 weeks. Resting-state functional magnetic resonance imaging was used to map correlations between brain networks and memory performance changes over time. Default mode networks (DMN), language and superior parietal networks were chosen as networks of interest to analyze the association with changes in verbal and visuospatial memory performance.

RESULTS:
Fourteen yoga and 11 MET participants completed the study. The yoga group demonstrated a statistically significant improvement in depression and visuospatial memory. We observed improved verbal memory performance correlated with increased connectivity between the DMN and frontal medial cortex, pregenual anterior cingulate cortex, right middle frontal cortex, posterior cingulate cortex, and left lateral occipital cortex. Improved verbal memory performance positively correlated with increased connectivity between the language processing network and the left inferior frontal gyrus. Improved visuospatial memory performance correlated inversely with connectivity between the superior parietal network and the medial parietal cortex.

CONCLUSION:
Yoga may be as effective as MET in improving functional connectivity in relation to verbal memory performance. These findings should be confirmed in larger prospective studies.

Interesting, but I do have a few concerns. The improvement in depression for the yoga group was statistically significant but the effect size was small:

the yoga group improved significantly in depression (GDS) and in visuospatial memory (Rey-O delayed recall). The clinical improvement in GDS for the yoga group was only minimal (baseline 7.5 (5.1) and follow up 3.9 (2.5); p = 0.01).

If you look at the table you will see that the control group also experience a reduction in depression, the fact that it did not achieve significant is likely an artifact of the study’s small sample size. Moreover, the yoga group started out with much higher depression scores suggesting that the groups might not have been comparable.

Here is the authors’ descriptions of the study’s limitations:

The sample size was only powered towards rs-fMRI findings, and exploring relationships between memory and functional connectivity, not exploring multi-domain effects on cognition. Additionally, we do not have long-term follow-up, which means we are unable to explore cognitive decline towards dementia. Also, it is possible that the enhanced cognitive benefits and connectivity changes resulting from the KK yogic intervention were due to the 60 min of instruction per week, the 12 min per day of Kirtan kriya meditation (shown to positively affect blood flow in the brain [34]), or a combination of these factors. However, as previous studies only using KK meditation found activation patterns that are in-line with those from the present research, it is unlikely that the weekly classes presented a large deviation. Nevertheless, this is a fruitful area for future research studies, which may aim to parse out the effects of these various activities, or perhaps determine that for optimal benefits weekly classes in addition to a daily meditative practice is recommended.

 

Could THC prevent Alzheimer’s disease?

8 Jul

My gut response to this is that it sounds too good to be true. But one should always keep an open mind.  Here is the description from the Salk Institute press release:

“Salk Institute scientists have found preliminary evidence that tetrahydrocannabinol (THC) and other compounds found in marijuana can promote the cellular removal of amyloid beta, a toxic protein associated with Alzheimer’s disease.

While these exploratory studies were conducted in neurons grown in the laboratory, they may offer insight into the role of inflammation in Alzheimer’s disease and could provide clues to developing novel therapeutics for the disorder.”

You can read the article abstract here.

Transcranial magnetic Stimulation, improves memory. Maybe.

3 Sep

A recent paper, in the prestigious journal Science, reports that transcranial magnetic stimulation may improve memory. Unfortunately, the article is behind a pay wall so I am unable to present a critical analysis. Here is the abstract:

“The influential notion that the hippocampus supports associative memory by interacting with functionally distinct and distributed brain regions has not been directly tested in humans. We therefore used targeted noninvasive electromagnetic stimulation to modulate human cortical-hippocampal networks and tested effects of this manipulation on memory. Multiple-session stimulation increased functional connectivity among distributed cortical-hippocampal network regions and concomitantly improved associative memory performance. These alterations involved localized long-term plasticity because increases were highly selective to the targeted brain regions, and enhancements of connectivity and associative memory persisted for ~24 hours after stimulation. Targeted cortical-hippocampal networks can thus be enhanced noninvasively, demonstrating their role in associative memory.”

From Science Daily here is a journalistic account of the research:

“Stimulating a region in the brain via non-invasive delivery of electrical current using magnetic pulses, called Transcranial Magnetic Stimulation, improves memory. The discovery opens a new field of possibilities for treating memory impairments caused by conditions such as stroke, early-stage Alzheimer’s disease, traumatic brain injury, cardiac arrest and the memory problems that occur in healthy aging.”

However, there has been some criticism of these findings (hat tip to Retraction Watch)

 

Electric Current to Brain Boosts Memory from Northwestern News on Vimeo.

Vitamin D deficiency increases risk of dementia

15 Aug

A recent paper in the journal Neurology: “Vitamin D and the risk of dementia and Alzheimer disease”

From the abstract:

“Our results confirm that vitamin D deficiency is associated with a substantially increased risk of all-cause dementia and Alzheimer disease. This adds to the ongoing debate about the role of vitamin D in nonskeletal conditions.”

The entire paper can be found here.

In this video, Dr. Greger talks about Vitamin D supplements:

 

“Alzheimer’s Disease Hits Women Hardest”

22 Jul

Justin Williams reports:

“The estimated risk of a woman developing Alzheimer’s disease in her 60s is 1 in 6, the Alzheimer’s Association says, compared to 1 in 11 for breast cancer.”

According to the Alzheimer’s Association:

“Not only are women more likely to have Alzheimer’s, they are also more likely to be caregivers of those with Alzheimer’s. More than 3 in 5 unpaid Alzheimer’s caregivers are women – and there are 2.5 more women than men who provide 24-hour care for someone with Alzheimer’s.”

 

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Remaining Lifetime Risk of Women Developing Alzheimer’s Disease and Breast Cancer, source Alzheimer’s Association

Cognitive effects of Mediterranean diet differ by race

19 Jul

A potentially important finding:

‘”In a population of initially well-functioning older adults, we found a significant correlation between strong adherence to the Mediterranean diet and a slower rate of cognitive decline among African American, but not white, older adults. Our study is the first to show a possible race-specific association between the Mediterranean diet and cognitive decline,” a researcher outlines.’

The full abstract can be found here. This may explain why some studies report no cognitive benefit from the Mediterranean diet. It also reminds us of the importance of accounting for moderating factors in research.

 

 

More good news on exercise and Alzheimer’s

4 Jul

From The New York Times, “Can Exercise Reduce Alzheimer’s Risk?”

“Exercise may help to keep the brain robust in people who have an increased risk of developing Alzheimer’s disease, according to an inspiring new study. The findings suggests that even moderate amounts of physical activity may help to slow the progression of one of the most dreaded diseases of aging.”

You can read the original paper here. Here is the abstract:

“We examined the impact of physical activity (PA) on longitudinal change in hippocampal volume in cognitively intact older adults at varying genetic risk for the sporadic form of Alzheimer’s disease (AD). Hippocampal volume was measured from structural magnetic resonance imaging (MRI) scans administered at baseline and at an 18-month follow-up in 97 healthy, cognitively intact older adults. Participants were classified as High or Low PA based on a self-report questionnaire of frequency and intensity of exercise. Risk status was defined by the presence or absence of the apolipoprotein E-epsilon 4 (APOE-ε4) allele. Four subgroups were studied: Low Risk/High PA (n = 24), Low Risk/Low PA (n = 34), High Risk/High PA (n = 22), and High Risk/Low PA (n = 17). Over the 18 month follow-up interval, hippocampal volume decreased by 3% in the High Risk/Low PA group, but remained stable in the three remaining groups. No main effects or interactions between genetic risk and PA were observed in control brain regions, including the caudate, amygdala, thalamus, pre-central gyrus, caudal middle frontal gyrus, cortical white matter (WM), and total gray matter (GM). These findings suggest that PA may help to preserve hippocampal volume in individuals at increased genetic risk for AD. The protective effects of PA on hippocampal atrophy were not observed in individuals at low risk for AD. These data suggest that individuals at genetic risk for AD should be targeted for increased levels of PA as a means of reducing atrophy in a brain region critical for the formation of episodic memories.”

brainex

Nelson Dellis at APS

25 May

I had the great pleasure of seeing memory champion Nelson Dellis performing last night. Dellis, who is also an avid mountain climber, is sponsoring a charity called Climb for Memory that raises funds for Alzheimer’s disease.

I post the full video if makes it available. In the mean time here is a short video of Dellis:

 

 

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Magnesium – Alzheimer study retracted

19 Apr

Some months ago I blogged about research that suggested that magnesium might help prevent Alzheimer’s dementia. At the time I wrote:

“This is an interesting result but please note that the research was funded by a pharmaceutical company that might have an interest in the outcome. In addition, the sample size was small. There is a recurring arc for this type of claim; initial studies with small sample sizes show large effects while later, better designed, research finds no or little effect. Best to keep an open mind but be willing to re-evaluate in the face of new evidence.”

Now the site Retraction Watch reports that The Journal of Neuroscience has retracted one of these papers. You can read the retraction statement here. The authors report methodological errors that will require them to rewrite the paper. But they claim:

“Despite these errors, the major conclusions of the paper remain substantiated”

So, in fairness, the question of magnesium role in preventing Alzheimer’s remains open. I repeat what I wrote in an earlier post:

“I certainly cannot dismiss the claims that magnesium may have cognitive benefits, but I would like to evidence independent of a researcher with a stake in the outcome.”

 

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