19 mars 2010
Since the early twentieth century, when Alois Alzheimer and Emil Kraepelin constructed it as a unified clinical-pathological entity, Alzheimer’s disease has been both one of the most stable and one of the most problematic neuropsychiatric entities.
Alzheimer’s (listed as Dementia of the Alzheimer’s Type in DSM-IV) remains one of the very few instances in which psychiatry has managed to associate a well-defined clinical syndrome – global deterioration of cognitive ability – with clear-cut brain pathology – the senile plaques and neurofibrillary tangles that continue to be regarded as the essential biomarkers of the disease.
And yet it has been one the most problematic of disease entities because – despite the relative clarity around its clinical symptoms and pathological correlates – a clear boundary has not been established between Alzheimer’s and aging. The cognitive deterioration that defines Alzheimer’s and other forms of dementia is experienced by everyone as they age, though to a much lesser degree in people not diagnosed. Similarly, decades of accumulated autopsy evidence has demonstrated that the plaques, tangles and all other putative biomarkers for Alzheimer’s and other major forms of dementia are found to varying degrees in all aging brains.
Thus on evidentiary grounds, at least as good a case can be made for viewing Alzheimer’s as an endpoint on a spectrum of cognitive changes associated with normal aging as for viewing it as a disease. But for political reasons, since the 1970s psychiatrists, neurologists, and Alzheimer’s advocates in the United States and Europe, have overwhelmingly asserted that it should be regarded as a disease. These political reasons can be summed up succinctly: government funds research for dread disease, not for discovering the fountain of youth. And as a political construct, Alzheimer’s as dread disease has been wonderfully successful at winning federal funding for research.
But critics – most notably neuroscientist Peter Whitehouse and anthropologist Daniel George in the their book The Myth of Alzheimer’s, have argued that the Alzheimer’s disease construct represents the medicalization of brain aging and profoundly exacerbates the stigmatization of age-associated cognitive decline.
To no one’s surprise, the draft of DSM-V does not back off of the commitment to viewing Alzheimer’s and similar conditions as disease entities distinct from aging. But it does propose two significant changes that, while well-intentioned, may greatly extend the medicalization of aging and worsen the stigma of age-associated cognitive decline.
Perhaps the most dramatic change related to these conditions in the draft DSM-V is the proposal to drop the term “Dementia” and replace it with the term “Major Neurocognitive Disorder.” The stated rationale for the proposed change mostly focuses on nosological considerations that seem on the whole sensible to address. But interestingly, the rationale also notes that the term dementia has “acquired a pejorative or stigmatizing connotation.” For just this reason, even critics of the Alzheimer’s disease construct seem to be welcoming this proposed change (for example, see the comments to the Myth of Alzheimer’s blog post on DSM-V changes.)
I am less optimistic that the ostensibly more neutral language of neurocognitive disorder will significantly lessen the stigma associated with Alzheimer’s disease or the milder cognitive impairments associated with aging. To be sure, the label dementia is deeply stigmatizing. But its stigmatizing power comes not from the word itself but from a deeper cultural impulse of marginalization. As long as we judge the worth of human beings by normative standards of productivity and competence, any label used to denote an impairment that prevents an individual from meeting those standards will soon enough come to be stigmatizing. Absent any meaningful attempt to change the normative standards that drive the stigmatization of aging and cognitive impairment, changes in terminology will not be de-stigmatizing but merely euphemistic. To the degree that the deployment of euphemism allows us to ignore unpleasant realities and shirk difficult social and cultural work, it will do more harm than good.
The other major change related to age-associated cognitive deterioration in the draft DSM-V is the proposal to add the category “Minor Neurocognitive Disorder” to recognize “the substantial clinical needs of individuals who have mild cognitive deficits in one or more of the same domains but can function independently… often through increased effort or compensatory strategies.”
The creation of the “Minor Neurocognitive Disorder” is an especially worrisome example of what, in a post to h-madness a couple of days back, Allan Horwitz characterized as a “Trojan horse that would diagnose nearly a-symptomatic people as being in the early stages of a disorder.” While such early diagnosis and treatment might be a well-intentioned effort to make help available early on, or to enhance investigation of the causes of a disorder, it has clear potential for abuse by a pharmaceutical industry eager to expand the market for their goods. This potential can be seen in the stated rationale for the proposal, which notes that early recognition of
“Mild Cognitive Impairment may be particularly critical, as it may be a focus of early intervention. Early intervention efforts may enable the use of treatments that are not effective at more severe levels of impairment and/or neuronal damage, and, in the case of neurodegenerative disease, may enable a clinical trial to prevent or slow progression.”
This is a fairly transparent statement of the hope that the drugs found to be of dubious value to patients diagnosed with Alzheimer’s disease might be found to offer greater benefit to patients in prodromal stages – or at least to generate more profits for drug companies.
The proposed diagnostic criteria for Alzheimer Subtype of Major or Minor Neurocognitive Disorders in the draft DSM-V stops just short of endorsing Mild Cognitive Impairment (MCI) as a prodrome of Alzheimer’s disease. The stated rationale for the proposal notes that research is ambiguous. Patients with MCI in memory disorder clinics have been shown to progress to Alzheimer’s at a rate of 12-15% per year, but population-based studies show a much lower rate of progression, with some individuals actually improving. Thus, the predictive value of MCI (or what under DSM-V will be called Minor Neurocognitive Disorder with Memory Impairment) does not warrant an automatic diagnosis as prodromal Alzheimer’s disease. The diagnostic criteria require not only evidence of mild memory impairment, but “clear supporting evidence for the Alzheimer etiology (e.g., a positive test for a known mutation in an Alzheimer’s disease associated gene), or with evolving research, documentation based on biomarkers or imaging.”
A positive test for one of the Alzheimer’s genes is a high diagnostic hurdle that would function to prevent dramatic inflation of this diagnostic category, but given the value to many powerful interests of very early Alzheimer’s diagnosis, who can doubt that progress in biomarkers and imaging will be quickly forthcoming? Smart money should be investing in pharmaceutical companies that stand to tremendously enlarge the market for drugs that have proven to be of dubious value for people diagnosed with Alzheimer’s.
And once every senior moment is diagnosable, we really will have reached the point – as Horwitz right worries – of pathologizing everyone.
This post can also be find on Alt(z)heimer
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