Alzheimer’s disease, familial hypercholesterolemia, and clinical trials

Welcome Jesse Ballenger to the blogosphere.  Jesse is a historian who specializes in the history of medicine and is the author of Self, Senility and Alzheimer’s Disease in Modern AmericaGary Schwitzer alerted me to Jesse’s post on Gina Kolata’s recent Sunday New York Times piece, How Do You Live Knowing You Might Have an Alzheimer’s Gene?, as well as to the existence of his blog, To Conquer Confusion:  A Historian’s Perspective on the Science and Experience of Alzheimer’s Disease and Dementia.  Jesse has both praise and criticism for Kolata’s story, and his post brings needed perspective on the history of research on Alzheimer’s as well as on the choice on Kolata’s part to present only the very optimistic views of certain Alzheimer’s researchers who “say that within a decade there could be a drug that staves off brain destruction and death.”  I agree with him that “Kolata should have raised questions about this claim, and talked to experts not directly involved in the research who are far less optimistic about its potential to so quickly lead to effective treatments.”  So please go read his post.

Kolata describes an American family in which many members are afflicted with early-onset Alzheimer’s caused by an autosomal dominant mutation.  Because the mutation is dominant, each affected family member has a 50% chance of passing the mutation on to each of his or her chidren.  The story is tragic and brought to my mind the emotions I experienced in 2001, when my daughter was diagnosed with heterozygous familial hypercholesterolemia (heFH) at age 8.  This is a genetic disease that causes very high LDL-cholesterol from birth and if untreated leads to early heart disease in a high percentage of patients.  At the time, I was only vaguely aware that there was a history of heart disease in my husband’s family and that his mother had had a heart attack.  At the urging of my daughter’s cardiologist, we asked my husband’s mother for more details and learned that her father had died of a heart attack at 35 and her brother, her only sibling, died of a heart attack at 40.  My mother-in-law suffered her first heart attack at age 58.  My husband inherited the mutation but has only a mild case, and my mother-in-law had never been told anything other than that she had high cholesterol, so my daughter’s diagnosis was the first occasion anyone in the family realized that the family history of early heart attacks was caused by a mutation.  Fortunately, unlike the case of Alzheimer’s disease, the risk associated with heFH can now be greatly reduced if patients are treated from an early age with a statin.  Homozygous FH patients, who have two copies of an FH mutation, are not so lucky and usually must undergo LDL apheresis on a regular basis.

Back to Kolata’s article:  I want to expand a little on a comment I wrote on Jesse’s post.  My comment related to Kolata’s comparison between the development of statins and the development of drugs to prevent Alzheimer’s.  As described in Kolata’s article, certain drugs in development are being tested in persons who are carriers of an Alzheimer’s mutation but have not yet developed symptoms of the disease.  The patients will receive one of several drugs or a placebo, and will be monitored for the development of certain biomarkers and, importantly, for the development of memory problems.  Kolata states that “Statins, the drugs that are broadly prescribed to block the body’s cholesterol synthesis, were first found effective in studies of people who inherited a rare gene that led to severe and early heart disease.”

The disease Kolata is presumably referring to is FH, but whether her statement is accurate depends on how one defines “effective.”  Early in the development of statins, after they had been tested in animals, they were given to a few patients with homozygous FH and heterozygous FH, as described in this 1992 article in the Journal of Lipid Research.  However, at that time the drugs were only being tested for their ability to lower LDL and for safety.  LDL-lowering is a surrogate endpoint.  If by “effective” one means the prevention of heart attacks and other cardiovascular events, the statement is inaccurate. When statins came on the market in the late 1980s, FH patients were excluded from the clinical trials that were conducted to show than statins not only lowered LDL but also prevented heart attacks, strokes and death. It was considered unethical to give an FH patient a placebo. To this day, no randomized controlled trial of statins with clinical endpoints has been done in FH patients and it is unlikely that one will ever be done. 

Direct evidence of the effectiveness of statins in heFH includes two observational studies, one of patients in a British registry and one of patients in a Dutch registry.  In addition, the ASAP trial compared a high dose statin with a moderate dose statin in heFH patients, but the endpoint was carotid intima media thickness, “IMT” (i.e., thickness of the carotid artery measured by ultrasound).  There was also a trial of statin vs. placebo in teenage FH patients using IMT as an endpoint.  In addition, many trials of statins have shown a benefit in non-FH patients with elevated LDL and it is reasonable to assume that this benefit would carry over to FH patients.

Thus, the comparison between the trials of investigational Alzheimer’s drugs in mutation carriers and the testing of statins in FH patients is not particularly apt.  The Alzheimer’s trials in patients with hereditary Alzheimer’s will be measuring the development of clinical symptoms of Alzheimer’s (i.e., memory loss, confusion, etc.).  The tests of statins in FH patients looked only at the effect of the drug on a surrogate endpoint (i.e., LDL-lowering) and no trials with clinical endpoints (i.e., heart attacks and other cardiovascular events and death) were done in FH patients.

References

Endo A.  The discovery and development of HMG-CoA reductase inhibitors. J. Lipid Res. 1992 33:(11) 1569-82. 

Neil A, Cooper J, Betteridge J, et al. Reductions in all-cause, cancer, and coronary mortality in statin-treated patients with heterozygous familial hypercholesterolaemia: a prospective registry study. Eur Heart J 2008; 29: 2625-2633.

Versmissen J, Oosterveer DM, Yazdanpanah M, et al. Efficacy of statins in familial hypercholesterolaemia: a long term cohort study. BMJ 2008; 337: a2423.
 
Sijbrands E.  Inhibition of PCSK9 in Familial Hypercholesteolemia.  The Lancet, Early Online Publication, 26 May 2012.
 
 

Posted on June 24, 2012, in cardiology and tagged , , , , , , , , . Bookmark the permalink. 2 Comments.

  1. Robert Bramel

    Hi Marilyn!
    I was just doing another one of my searches on FH and encountered your blog. The post must be at least a year old and I don’t know if you are still looking for comments. I have HeFH and have found a great deal of information about the condition. I can report personally that there are many cases (almost always unreported in the medical community) where a lifetime of extreme C and LDL have absolutely no adverse consequences. I’m 68 and my LDL has always been extreme. For the last 8 years my LDL alone has been above 500, yet by EBCT my arteries are completely clear – no calcified plaque at all! My relevant family history back through my great-grandparents shows no heart attacks or early deaths, so clearly heart disease needs something more than just elevated serum lipids.
    As someone who suffered for decades with the cloud of instance death hanging over me I think it is extremely important to separate out those with a real risk (plaque buildup) from those at little to no risk. As for treating children with statins, I think it would be essential to see data showing a real substantial risk reduction before subjecting a child to any lowering drug. Remember, the brain is “the” king of cholesterol use and there are no studies showing the long term effects of statins on children.
    I have tons more information about FH if you are interested. Let me know.

    Robbramel@gmail.com

    Like

  2. Dear Robert

    I’m certainly glad to hear you are in good health.

    I agree with you that data are lacking showing that starting children with FH on statins prevents more heart attacks than waiting until they are adults. So, if a parent of a child with FH decides not to put them on a statin, I have no problem with that. I also have no problem with a parent who decides to let their child be prescribed a statin. Given the uncertainty, there is no right answer.

    I doubt there will ever be convincing data showing that started statins in childhood prevents more heart attacks than waiting until adulthood, because it is not practical to conduct a randomized controlled trial on that question. Perhaps in the future there will be some observational data on that question.

    As for adults with FH who don’t develop heart disease — there are some people in that situation but it is difficult to predict who will develop heart disease and who won’t.

    If you have studies on FH you want to send me, my email is mannm@comcast.net.

    Best
    Marilyn

    Like

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