July 29, 2013

12 important things to know about wind farms, health and nocebo effects, by Simon Chapman

Simon Chapman, the Australian misocapnist, has just posted a video lecture outlining his thoughts about wind turbines and health, titled "12 things you need to know about wind farms and health". It's more than 26 minutes long, and seemingly designed to bore the viewer so much that they will give up and take his thesis on faith. Your editor, however, sat through the whole thing and here raises some issues with Professor Chapman's presentation.

1. Modern wind farms have existed since early 1980s.

2. Health objections to wind farms are relatively recent [since 2002].

The obvious question is, has anything in the nature of wind farms changed?

The numbers of wind turbines have increased steadily over the past decade, so it is not surprising to find that they have affected more people.

(source: Garrad Hassan, 2008)

(source: National Renewable Energy Laboratory, 2012)

Furthermore, the size of wind turbines made a distinctive leap around the year 2000. Larger sizes and higher towers mean more noise travelling farther, and particularly more low-frequency noise, which travels even farther and does not stop at — in fact, often resonates with — walls and windows.

3. Opponents claim there are immediate and long-term health impacts.

Chapman illogically presents examples of no effects reported as proof that instances of reported effects are false and again dodges the obvious question of mechanism: size and number of turbines, distance from homes, nature of noise that affects some people and not others. Nina Pierpont suggested an inner ear disturbance (like motion sickness) caused by low-frequency noise from large (post-2000) wind turbines sited within 1-2 km from homes. Before then, low frequencies were not considered in noise measurements. Since then, low-frequency noise has indeed been measured in the homes of affected individuals. See, e.g.:

"Dynamic measurements of wind turbine acoustic signals"
"The Bruce McPherson Infrasound and Low Frequency Noise Study"
"Cooperative Measurement Survey and Analysis of Low-Frequency and Infrasound at the Shirley Wind Farm"

4. Even a majority of wind farms with large turbines have zero complaint history.

This claim has been critiqued elsewhere.

5. The number of people complaining about health or noise is very small.

There is no actual registry of such complaints. Chapman is making it up. Companies do not report such complaints. Leases and easements typically prevent public disclosure of complaints if the person wants payments to continue. Chapman's "study" relies on parliamentary testimony, which would represent a very small fraction of affected people (he makes no attempt to estimate the degree of such sampling), media coverage, which of course varies tremendously in interest and bias and can not be comprehensive, and records of the wind companies themselves, apparently accepted without question or verification.

6. The "susceptibility" analogy with motion sickness does not stack up.

Actually, it does, but such nuance doesn't fit Chapman's neat theories. Update, August 4: This just in!

7. You name it ... they say wind farms cause it: 223 and growing!!

Since the primary vectors are stress and disturbed sleep, the broad range of effects — on all animals, not just humans — is not surprising. Chapman then picks out a few of the most extreme, ignoring exacerbation, to discount all reported effects. He also (in typical fashion) misreports them: for example, the "sudden death of 400 goats" he mocks as "seriously a report that was on the web attributed to wind turbines"; in fact, the story from Taiwan was the death of 400 goats over 3 years, beginning when a neighboring wind farm started operation, as reported by the Taiwan Council of Agriculture.

8. Many of the most commonly named problems are very common in any community.

And are more common after wind turbines start operating.

9. Complainants have refused to provide their medical records.

This charge is based on one appeal of a project approval in Ontario — Zephyr Farms in the township of Brooke-Alvinston, Lambton County — where the appellant was told to hand over the complete private health records of 20 individuals, despite their existing sworn testimony, within 1 week — which would then be considered only for "serious" harm to human health. Faced with this impossibility (not to mention the invasiveness), the appellant withdrew (the case was not "thrown out" as Chapman says). Since that project was erected, the adverse health effects warned of by the appellant have indeed occurred. Later such requests in Ontario for medical records have been met (e.g., at the hearing for Ostrander Point), as appellants know what to expect and have time to collect them.

10. Most complaints occur at wind farms targeted by anti-wind farm groups, mostly post 2009.

Duh. The groups provide a medium for publicizing complaints that are otherwise ignored or mocked. And the groups can not be active everywhere at once.

11. There have been 19 reviews of the evidence on wind farms, noise and health since 2003.

Actually, there seem to have been 28 so far, almost all of them, even some of those sponsored by the industry itself, recognizing the need for more research. Update, November 13, 2013:  Make that 35. But only 10 non-industry, non-government reviews.

12. Money may be a magic antidote to complaints.

With the use of the word "magic", Chapman shatters his whole charade of objective inquiry. It must be again noted that the receipt of money from wind companies typically requires silence about problems, a kind of inverse extortion. Chapman has been reassured by wind companies that there are no such gag clauses (which of course are illegal). Nevertheless, many individuals who lease their land for wind turbines do in fact complain of ill effects.

Conclusion:  "What we're seeing is what we call ah um an incidence of psych psychogenic illness." (nervous artifacts transcribed to indicate possible deliberate dishonesty)

Chapman defines psychogenic illness as "a constellation of symptoms suggestive of organic illness, but without an identifiable cause, that occurs between two or more people who share beliefs about those symptoms".

But adverse health effects from wind turbines are not "suggestive" of illness, they are illness. And nearby wind turbines are the easily identifiable cause. As for "shared beliefs", that applies to any illness, but in the case of wind turbines it is well documented that just as many people with a prior favorable view of them get sick as those with a previously more skeptical view. (An early example [2007] is Jane Davis of Deeping St Nicholas, England, and similar testimony of prior support and subsequent distress is indeed common.)

Chapman's suggested cure is apparently to suppress the issue in public and professional discourse, because the only real solution is to keep giant wind turbines an adequate distance from homes, workplaces, and recreational areas.

He quotes Francis Bacon (the alchemist): "Infections ... if you fear them, you call them upon you." The germ theory of infection has long proven that to be nonsense, just as continuing research in the physiological effects of low-frequency noise is validating the connection between giant wind turbines and adverse health effects.

(Chapman also takes the Bacon quote far out of context. It is from an essay on envy published in 1625:
Now, to speak of Public Envy :  There is yet some good in Public Envy, whereas in Private, there is none.  For Public Envy is as an ostracism, that eclipseth Men when they grow too great :  and therefore it is a bridle also to Great Ones, to keep them within Bounds.

This Envy, being in the Latin word Invidia, goeth in the Modern Languages by the name of Discontentment ;  of which we shall speak in handling Sedition.  It is a Disease in a State like to Infection ;  For as Infection spreadeth upon that which is sound, and tainteth it ;  so when Envy is gotten once into a State, it traduceth even the best Actions thereof, and turneth them into an ill Odour.  And therefore there is little won by intermingling of plausible Actions :  for that doth argue but a Weakness and Fear of Envy ;  which hurteth so much the more, as it is likewise usual in Infections, which, if you fear them, you call them upon you.
(Bacon seems to be saying that if you act in fear of envy, you invite it; but also that if you fear not envy, it will find you out anyway. His use of infection is clumsy as a metaphor, especially as he considers public envy a worthwhile check on power.)

Chapman goes on to present his "nocebo" thesis, despite the fact that people are not barraged with "fear mongering", but rather the opposite, with government, media, nonprofits, and educational institutions pitching industrial wind turbines as utterly benign. If he insists on the existence of a nocebo effect, then he has to explain the failure of this "placebo" innoculation against ill effects.

Chapman then moves on to attack Nina Pierpont, who described the consistent set of symptoms that she called "wind turbine syndrome", and proposed a mechanism that elegantly fits the facts, as mentioned above.

After a bit more mockery of complaints and advocates, he explains why this issue is so serious. No, it's not because the effect of low-frequency and pulsating noise from industrial wind turbines on public health needs to be more seriously studied. Simon Chapman, of the University of Sydney School of Public Health, is concerned instead that developers can not erect wind turbines anywhere they want. For example, he inaccurately describes the state of Victoria's designation of a 2-km buffer zone around wind turbines as a ban on erecting them closer to homes. In fact, Victoria simply allows a resident within that distance to say "no, thank you". These are not "no go zones", as Chapman claims. If he and his industry cronies were convincing about the lack of adverse health effects, they would have no worries. But unfortunately for their (publicly subsidized) business, the facts speak louder than their denial of them.

wind power, wind energy, wind turbines, wind farms, environment, environmentalism, human rights, animal rights

July 27, 2013

Bipartisan war on civil liberties

Glenn Greenwald writes on the congressional failure to rein in NSA spying:

... But perhaps the most significant and enduring change will be the erosion of the trite, tired prism of partisan simplicity through which American politics has been understood over the last decade. What one sees in this debate is not Democrat v. Republican or left v. right. One sees authoritarianism v. individualism, fealty to The National Security State v. a belief in the need to constrain and check it, insider Washington loyalty v. outsider independence.

That's why the only defenders of the NSA at this point are the decaying establishment leadership of both political parties whose allegiance is to the sprawling permanent power faction in Washington and the private industry that owns and controls it. They're aligned against long-time liberals, the new breed of small government conservatives, the ACLU and other civil liberties groups, many of their own members, and increasingly the American people, who have grown tired of, and immune to, the relentless fear-mongering.

The sooner the myth of "intractable partisan warfare" is dispelled, the better. The establishment leadership of the two parties collaborate on far more than they fight. That is a basic truth that needs to be understood. As John Boehner joined with Nancy Peolsi, as Eric Cantor whipped support for the Obama White House, as Michele Bachmann and Peter King stood with Steny Hoyer to attack NSA critics as Terrorist-Lovers, yesterday was a significant step toward accomplishing that.

human rights, anarchism

July 23, 2013

The descent of book design

I have just enjoyed reading John Saturnall’s Feast by Lawrence Norfolk, but I was troubled by some aspects of the book design.

First, the title font seemed incongruous, evoking 1890s art nouveau rather than the 1630s and following decades of the book’s setting, particularly when used as large drop caps after the floral “woodcut” initial caps of the excerpts of “The Book of John Saturnall” that precede each chapter. The opening page of each chapter also sports the chapter’s running title, which is unusual and looks like a mistake, since the large drop cap indicates that it is an opening, not a running, page.

Second, The drop caps are set as if by a word processor, i.e., by lazily clicking “Drop Cap” in the layout program without regard to design or readability.

There were also some other glaring typesetting and layout errors, though overall the text itself was well set. Finally, the dust cover curled so badly that it had to be taken off while reading (which some people do anyway, but more usually to preserve the cover of an old book, not one that’s brand new).

Then I realized my mistake: I had bought the U.S. edition, forgetting to seek out the original British edition first. Bloomsbury first published the book in the U.K., and Grove published it in the U.S. Following are the first few pages of each edition side by side. The Bloomsbury images are screen captures from Amazon UK, and the Grove images are my own scans. (Although the Bloomsbury drop caps do not conform to the modern ideal, they are actually true to how books were set in the late 17th century, which those pages successfully evoke. The Grove edition sets these sections just like the rest of the text, only ragged right.)

Note, the British paperback appears to use the Grove edition, which suggests the driving aesthetic behind the latter: to be trade paperback ready. Note the larger text font, ready for photo-reduction. And the gaudy cover.

[[[[ ]]]]

Apart from its degraded vessel, John Saturnall’s Feast is a compelling fantasy about the power of cooking, representing alchemical wizardry and creativity to woo, mock, and sustain in lean times as well as flush. And ultimately to cross barriers, to subvert orders, to assert an older magic, older gods, a natural order.

Land use and solar power

Here is a list of a few solar "farms", i.e., fields of photovoltaic panels, in Ontario

Amherstburg: 10 MW on 196 acres (79 ha)
Belmont: 20 MW on 448 acres (181 ha)
St Clair: Moore Solar Farm: 20 MW on 297 acres (120 ha)
St Clair: Sombra Solar Farm: 20 MW on 347 acres (140 ha)
Walpole: 20 MW on 344 acres (139 ha)

The average is 18.1 acres (7.3 ha) per MW of installed capacity.

Granting a generous average capacity factor of 15%, that comes to 121 acres (49 ha) per MW of average output.

The average per-capita electricity load is about 1.9 kW in Canada, which comes to almost a quarter-acre of solar panels per person.

But the sun doesn't shine brightly all the time, and not at all at night. So, even with more favorable numbers, all of that acreage paved over with solar panels is sacrificed in addition to continuing reliance on other sources.

environment, environmentalism

July 21, 2013

Slate notices the misapplication of climate action

From a couple of recent articles at Slate.com ...

Mark Hertsgaard, Tuesday, July 2, 2013:
Eating beef is particularly environmentally damaging: Cows are less efficient than chickens or pigs at converting corn (or other feed) into body weight, so they consume more of it than other livestock do. As a result, the industrial agriculture system employs 55 calories of fossil fuel energy to produce 1 calorie of beef. Meanwhile, livestock production is responsible for much of the carbon footprint of global agriculture, which accounts for at least 25 percent of humanity’s annual greenhouse gas emissions, according to the U.N. Food and Agriculture Organization.

Despite its large carbon footprint, the agricultural sector is invariably overlooked in climate policy discussions. The latest example: In his 50-minute speech on climate change last week, President Barack Obama did not even mention agriculture except for a half-sentence reference to how farmers will have to adapt to more extreme weather.
(The rest of Hertsgaard’s article delves into the “responsible meat” fantasies of Michael Pollan, in denial of the facts just spelled out here.)

David Biello, Tuesday, July 16, 2013:
Few would have to change their livelihoods as radically as American farmers if efforts to combat climate change became more serious. ... [T]he biggest change delivered by science to farming in the past century is ... the advent of fossil-fuel-powered machinery and fertilizer wrested from the air by chemistry. That, along with cutting down forests to make room for farms around the world, makes agriculture the second-largest cause of the greenhouse gas emissions changing the climate. There's methane from massive meat farms and manure lagoons. There's nitrous oxide — yes, the stuff used at the dentist’s office — seeping out of the soil thanks to all that nitrogen fertilizer, and it's no laughing matter since N₂O is nearly 300 times more powerful as a greenhouse gas than CO₂ over a century [and persists in the atmosphere less than a tenth as long as CO₂, making it ~170-fold a more effective target for action. And methane is more than 20 times more powerful as a greenhouse gas than CO₂ over a century and persists in the atmosphere only 10 years, making it ~200-fold a more more effective target for action.]
(The rest of Biello’s article mostly describes only reducing tillage, but with the example of using herbicides instead.)

Also noticing the misapplication of climate action is the National Academy of Sciences, in its recent report “Effects of U.S. Tax Policy on Greenhouse Gas Emissions”:
[T]he combined effect of current energy-sector tax expenditures on GHG emissions is very small and could be negative or positive. The most comprehensive study available suggests that their combined impact is less than 1 percent of total U.S. emissions. If we consider the estimates of the effects of the provisions we analyzed using more robust models, they are in the same range. We cannot say with confidence whether the overall effect of energy-sector tax expenditures is to reduce or increase GHG emissions.
environment, environmentalism, human rights, animal rights, vegetarianism, veganism

July 20, 2013

How to set a proper drop cap

A Proper Drop Cap

It is crucial to remember that the drop cap is part of the first line of text. It should therefore be set to be clearly attached to the first word, unless it is a single-letter word in itself, in which case the first line of text should be closer than the subsequent lines to the drop cap. After a drop cap, it is also customary to set the rest of the first word in caps or a few words in small caps.

The space between the drop cap and the lines after the first should be visually equal to the space between lines. That is, except for its connection to the first line, a drop cap should have equal space around it, both to the right and below.

A drop cap usually looks better balanced if it overhangs the left text margin slightly. The amount varies with the shape of the letter.

How to Set a Proper Drop Cap

Do not use the automatic “Drop Caps” feature in the paragraph style. This is typography, not word processing.

Delete the first letter of the text and set the paragraph without opening indentation.

Set the initial cap in its own frame or text box, or picture box if it is a graphic.

Size and style the drop cap as desired.

Make sure the drop cap box is in front of the text box.

Set the runaround or text wrap of the drop cap box to 0.

Position the drop cap box as desired.

Size the drop cap box to create the desired space around it (to the right and below).

Add a space at the start of the text, and tighten the kern space after it to move the text of the first line closer to the drop cap. The text should be close enough that it is clearly attached to the drop cap as a single word. If the drop cap is itself a single-letter word, the space should be visually consistent with the wordspaces of the rest of the line. If more kern-space adjustment is required than allowed by the typesetting program, repeat with another space to move the text further to the left.

If the bottom of the drop cap box interferes with the text below it, set the runaround or text wrap of its bottom edge to a negative value so that the text is not affected.

Example from Essays, or Counsels Civil and Moral [1812 and 1825] by Francis Bacon, George Bell and Sons, London, 1881:

July 17, 2013

This week in Windpower Monthly

12 July 2013: French wind industry in disarray following ECJ conclusion
The Advocate General of the European Court of Justice has concluded that the French tariff system for wind power falls within the concept of state aid.

12 July 2013: Uncertainty could derail Euro offshore growth, warns EWEA
Market uncertainty in Europe could lead to problems financing offshore projects and derail the growth in the sector, according to European Wind Energy Association.

15 July 2013: Spanish reform to deliver further blows
Spain's wind sector predicts "a torrent of financial problems" following Friday's approval of the Spanish government's power sector law, retroactively slashing returns on wind power generation.

16 July 2013: Greek draft law could break wind sector
The Greek government is drafting a law to push back the determination of a feed-in tariff (FIT) to the moment when a project is connected to the grid.

17 July 2013:
Forecast or pay penalties, India tells wind power producers

Wind farm operators in India now face fines if they fail to accurately predict their output for the following day under a new directive that came into force on 15 July.

10 July 2013: Iberdrola sells Turkish wind portfolio
Turkish engineering firm Guris has confirmed that it has acquired 100% of Spanish utility Iberdrola's wind portfolio in Turkey, totalling 133MW.

16 July 2013: Iberdrola seeks buyer for Romanian wind farms
Iberdrola has put Romanian wind assets on the sales block, as as the Spanish power company continues with the disposal of non-strategic assets.

1 January 2013: GE leads deal to buy Iberdrola wind farms
Iberdrola, the owner of Scottishpower, is selling its French wind farm business to a consortium led by American industrial giant General Electric for about €400 million (£326.4m) in its drive to cut debt and maintain an investment grade credit rating.

9 January 2013: Wind company leaves Hammond [New York]
Iberdrola Renewables has confirmed that the meteorological test towers have been disabled and the company will no longer pursue developing the Stone Church industrial wind farm in Hammond, a project the company has been courting for the past several years.

15 January 2013: Iberdrola: Uncertainty continues for wind project development
Iberdrola Renewables is again confirming its commitment to the U.S. market — and the Pacific Northwest — after reports that the company is abandoning wind projects in the face of a continued weak market for renewable energy. After a New York news weekly reported that Iberdrola was canceling 100 projects in the U.S., the company came out in news reports to reaffirm its plans to remain active developing renewable energy projects here, while acknowledging the pipeline will be "rightsized."

24 June 2013: Wind developer abandons Ellis County [Kansas] project
In a registered letter delivered to many residents in the area today, Iberdrola Renewables, LLC said, “A variety of circumstances have led the company to the conclusion that it cannot move forward with developing the wind resources on the Property. As such, pursuant to the terms of the Agreement, Iberdrola Renewables, LLC is terminating the Agreement effective July 20, 2013.”

wind power, wind energy, wind turbines, wind farms

July 12, 2013

Comments on July North American Windpower

A friend sent us a copy of this month’s issue of the trade journal North American Windpower, and it contains a couple of items that demand comment.

On page 20, the journal’s editor, Mark del Franco, reports “Obama Addresses Climate Change”:
The plan calls on the U.S. Department of the Interior to permit enough renewables projects on public lands by 2020 to power more than 6 million homes. According to the American Wind energy Association (AWEA), such an undertaking would require the construction of more than 11,000 wind turbines assuming a 35% capacity factor and an average turbine size of 2 MW.
Del Franco does not provide a critique of that plan, so here it is.

First, 11,000 2-MW wind turbines would require 1,000,000 acres, more than 1,500 square miles, not to mention massive new power lines (the cover story of this issue is about the 8-billion-dollar, 3,600-mile transmission project that will carry wind output from west Texas to the state’s load centers in the east).

Second, 11,000 2-MW wind turbines would cost more than 40 billion dollars, two-thirds of which would be public funds to ensure the enrichment of private energy investors. And the turbines last only 10-20 years, so such a cost would be recurring.

Third, “6 million homes” in the U.S. represents about 4% of residential use, 1.5% of total electricity use, 0.6% of total energy use, and 0.2% of total CO₂ emissions. (As calculated using data from the U.S. Department of Energy’s Energy Information Administration.)

In short: Obama’s climate action plan calls for 40+ billion dollars to industrialize 1,000,000 acres of public land to (theoretically) reduce CO₂ by 0.2%. (And if consumption continues to grow? Then that figure becomes even more insignificant. And if wind, an intermittent and highly variable source, makes other plants run less efficiently, ie, emit more CO₂ per unit of electricity fed into the grid? — Whoops!)

Also in this article, del Franco calls the AWEA an environmental and conservation group. From their own web site: “AWEA is a national trade association representing wind power project developers, equipment suppliers, services providers, parts manufacturers, utilities, researchers, and others involved in the wind industry.” It should be obvious that industrial-scale energy development that requires large areas of rural and wild land stands firmly against the concerns of environmental and conservation groups.

Finally, another piece by del Franco requires a quick comment, “How Wind Can Aid In Climate Change”, page 6:
He [Larry Schweiger, president and CEO of the National Wildlife Federation] says scientists are also studying the link between May’s deadly Oklahoma tornadoes and climate change, but at this moment scientists do not have sufficient data to conclusively link tornado frequency and intensity to a warming planet. “The point is we are changing the climate with carbon pollution, and that is triggering unprecedented and dangerous weather conditions around the world,” he says.
Wasn’t the point, “scientists do not have sufficient data” to conclusively link weather conditions to a warming planet? Never mind. The point for such industry apologists must always be that we need to promote extensive industrial wind development in our last remaining rural and wild places to reduce human emissions of CO₂ — by, maybe, 0.2%.

OK, one more: “Campaign Combats Anti-Wind Myths”, page 8:
“The wind industry is being attacked by media-savvy and politically influential adversaries who often display a brazen disregard for factual information ...,” comments Morten Albaek, Vestas Group senior vice president.
That is, comments a media-savvy and politically influential industry flack who often displays a brazen disregard for factual information. Not to mention the absurdity of well funded full-time developers, lobbyists, and consultants painting themselves as victims as they expand their campaigns against for the most part spare-time volunteer citizens’ groups.

wind power, wind energy, environment, environmentalism

July 9, 2013

Wishful thinking of wind energy proponents

To the Editor, Vermont Standard [July 3, 2013]:

Kurt Staudter claims knowledge from a quarter-century of working in the electric industry, but one big fact seems to have passed him by (“Not in My Back Yard, but OK in Yours,” While We Were Sleeping, June 27). It’s been decades since the U.S. has burned any significant amount of oil for electricity. While 9/11 may have been about oil, particularly that in Saudi Arabia, the U.S. seems to have invaded and remained in Afghanistan to gain uncontested access to central Asian gas fields. Wind energy has nothing to do with oil, which is used for transport and heating, but it depends a great deal on natural gas.

As Staudter knows, the electric grid has to maintain a steady flow of power equal to demand second by second. Since wind is highly variable, it needs to be balanced by generators that can ramp quickly up or down as needed to maintain steady power. Such generators are fueled by natural gas. So wind energy, rather than moving us away from the causes of 9/11, contributes instead to the “reasons” for continuing U.S. aggression in central Asia that makes another 9/11 more, not less, likely.

Staudter must also know that operating a generating plant with frequent rapid ons and offs wastes fuel and wears down the machinery faster. Several analyses have found that combined-cycle gas turbines alone — which are more efficient and possible without the balancing needs of wind — would have no more, or would have even less, emissions than open-cycle gas turbines required to work with wind.

Finally, Staudter says wind is cheap. If that’s his “trump card,” then we should all welcome fracking, tar sands, and mountaintop-removal coal. But in fact, turning wind into electricity is not cheap. It is a diffuse source of energy, so it requires a massive sprawling infrastructure to collect any meaningful amount — in addition to the balancing generators to make it useful to the grid. The simple fact is that wind energy requires subsidies covering two-thirds of the cost (thank you, ratepayers and taxpayers) to make any profit.

At best, wind turbines represent wishful thinking. But the industrialization of wild and rural places at such great public and ecological cost makes them much worse: a symbol of waste, folly, and profiteering. In other words, business as usual.

wind power, wind energy, wind turbines, wind farms, environment, environmentalism, Vermont

July 2, 2013

Vascular Contributions to Cognitive Impairment and Dementia

A Statement for Healthcare Professionals from the American Heart Association/American Stroke Association, by the American Heart Association Stroke Council, Council on Epidemiology and Prevention, Council on Cardiovascular Nursing, Council on Cardiovascular Radiology and Intervention, and Council on Cardiovascular Surgery and Anesthesia

Stroke. Published on line July 21, 2011. doi:10.1161/STR.0b013e3182299496


Background and Purpose — This scientific statement provides an overview of the evidence on vascular contributions to cognitive impairment and dementia. Vascular contributions to cognitive impairment and dementia of later life are common. Definitions of vascular cognitive impairment (VCI), neuropathology, basic science and pathophysiological aspects, role of neuroimaging and vascular and other associated risk factors, and potential opportunities for prevention and treatment are reviewed. This statement serves as an overall guide for practitioners to gain a better understanding of VCI and dementia, prevention, and treatment.

Methods — Writing group members were nominated by the writing group co-chairs on the basis of their previous work in relevant topic areas and were approved by the American Heart Association Stroke Council Scientific Statement Oversight Committee, the Council on Epidemiology and Prevention, and the Manuscript Oversight Committee. The writing group used systematic literature reviews (primarily covering publications from 1990 to May 1, 2010), previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and, when appropriate, formulate recommendations using standard American Heart Association criteria. All members of the writing group had the opportunity to comment on the recommendations and approved the final version of this document. After peer review by the American Heart Association, as well as review by the Stroke Council leadership, Council on Epidemiology and Prevention Council, and Scientific Statements Oversight Committee, the statement was approved by the American Heart Association Science Advisory and Coordinating Committee.

Results — The construct of VCI has been introduced to capture the entire spectrum of cognitive disorders associated with all forms of cerebral vascular brain injury—not solely stroke—ranging from mild cognitive impairment through fully developed dementia. Dysfunction of the neurovascular unit and mechanisms regulating cerebral blood flow are likely to be important components of the pathophysiological processes underlying VCI. Cerebral amyloid angiopathy is emerging as an important marker of risk for Alzheimer disease, microinfarction, microhemorrhage and macrohemorrhage of the brain, and VCI. The neuropathology of cognitive impairment in later life is often a mixture of Alzheimer disease and microvascular brain damage, which may overlap and synergize to heighten the risk of cognitive impairment. In this regard, magnetic resonance imaging and other neuroimaging techniques play an important role in the definition and detection of VCI and provide evidence that subcortical forms of VCI with white matter hyperintensities and small deep infarcts are common. In many cases, risk markers for VCI are the same as traditional risk factors for stroke. These risks may include but are not limited to atrial fibrillation, hypertension, diabetes mellitus, and hypercholesterolemia. Furthermore, these same vascular risk factors may be risk markers for Alzheimer disease. Carotid intimal-medial thickness and arterial stiffness are emerging as markers of arterial aging and may serve as risk markers for VCI. Currently, no specific treatments for VCI have been approved by the US Food and Drug Administration. However, detection and control of the traditional risk factors for stroke and cardiovascular disease may be effective in the prevention of VCI, even in older people.

Conclusions — Vascular contributions to cognitive impairment and dementia are important. Understanding of VCI has evolved substantially in recent years, based on preclinical, neuropathologic, neuroimaging, physiological, and epidemiological studies. Transdisciplinary, translational, and transactional approaches are recommended to further our understanding of this entity and to better characterize its neuropsychological profile. There is a need for prospective, quantitative, clinical-pathological-neuroimaging studies to improve knowledge of the pathological basis of neuroimaging change and the complex interplay between vascular and Alzheimer disease pathologies in the evolution of clinical VCI and Alzheimer disease. Long-term vascular risk marker interventional studies beginning as early as midlife may be required to prevent or postpone the onset of VCI and Alzheimer disease. Studies of intensive reduction of vascular risk factors in high-risk groups are another important avenue of research.

Click here for full text.

[The Alzheimer's Association: Some autopsy studies show that as many as 80% of individuals with Alzheimer disease also have cardiovascular disease. Autopsies of dementia patients diagnosed with Alzheimer disease showed that 54% had coexisting pathology. The most common coexisting abnormality was previously undetected blood clots or other evidence of vascular disease.]