How Leqembi became the biggest news in Alzheimer’s disease in 40 years, and what comes next
Betsy Groves, 73, with her granddaughter. Groves learned in 2021 that she has Alzheimer's disease. She hopes to take Leqembi, a drug approved by the FDA last week.
A few months ago, Betsy Groves traveled less than a mile from her home in Cambridge, Mass. to give a talk to a bunch of scientists. The scientists, who worked for the pharmaceutical companies Biogen and Eisai, wanted to know how she lived her life, how she thought about her future, and what it was like when a doctor’s appointment in 2021 gave her the worst possible news. Groves, 73, has Alzheimer’s disease. She caught it early, through a lumbar puncture that showed evidence of amyloid, an Alzheimer’s hallmark, in her cerebrospinal fluid. As a way of dealing with her diagnosis, she joined the Alzheimer’s Association’s National Early-Stage Advisory Board, which helped her shift into seeing her diagnosis as something she could use to help others.
After her talk, Groves stayed for lunch with the scientists, who were eager to put a face to their work. Biogen and Eisai were about to release the first drug to successfully combat Alzheimer’s in 40 years of experimental disaster. Their drug, which is known by the scientific name lecanemab and the marketing name Leqembi, was granted accelerated approval by the U.S. Food and Drug Administration last Friday, Jan. 6, after a study in 1,800 people showed that it reduced cognitive decline by 27 percent over 18 months.
It is no exaggeration to say that this result is a huge deal. The field of Alzheimer’s drug development has been absolutely littered with failures. Almost everything researchers have tried has tanked in clinical trials. “Most of the things that we've done have proven not to be effective, and it's not because we haven’t been taking a ton of shots at goal,” says Anton Porsteinsson, director of the University of Rochester Alzheimer's Disease Care, Research, and Education Program, who worked on the lecanemab trial. “I think it's fair to say you don't survive in this field unless you're an eternal optimist.”
As far back as 1984, a cure looked like it was within reach: Scientists discovered that the sticky plaques that develop in the brains of those who have Alzheimer’s are made up of a protein fragment called beta-amyloid. Buildup of beta-amyloid seemed to be sufficient to disrupt communication between, and eventually kill, memory cells. If that was true, then the cure should be straightforward: Stop the buildup of beta-amyloid; stop the Alzheimer’s disease.
It wasn’t so simple. Over the next 38 years, hundreds of drugs designed either to interfere with the production of abnormal amyloid or to clear it from the brain flamed out in trials. It got so bad that neuroscience drug divisions at major pharmaceutical companies (AstraZeneca, Pfizer, Bristol-Myers, GSK, Amgen) closed one by one, leaving the field to smaller, scrappier companies, like Cambridge-based Biogen and Tokyo-based Eisai. Some scientists began to dismiss the amyloid hypothesis altogether: If this protein fragment was so important to the disease, why didn’t ridding the brain of it do anything for patients? There was another abnormal protein that showed up in the brains of Alzheimer’s patients, called tau. Some researchers defected to the tau camp, or came to believe the proteins caused damage in combination.
The situation came to a head in 2021, when the FDA granted provisional approval to a drug called aducanumab, marketed as Aduhelm, against the advice of its own advisory council. The approval was based on proof that Aduhelm reduced beta-amyloid in the brain, even though one research trial showed it had no effect on people’s symptoms or daily life. Aduhelm could also cause serious side effects, like brain swelling and amyloid related imaging abnormalities (known as ARIA, these are basically micro-bleeds that appear on MRI scans). Without a clear benefit to memory loss that would make these risks worth it, Medicare refused to pay for Aduhelm among the general population. Two congressional committees launched an investigation into the drug’s approval, citing corporate greed, lapses in protocol, and an unjustifiably high price. (Aduhelm was also produced by the pharmaceutical company Biogen.)
To be clear, Leqembi is not the cure Alzheimer’s researchers hope for. While the drug is the first to show clear signs of a clinical benefit, the scientific establishment is split on how much of a difference Leqembi will make in the real world.
So far, Leqembi is like Aduhelm in that it has been given accelerated approval only for its ability to remove amyloid from the brain. Both are monoclonal antibodies that direct the immune system to attack and clear dysfunctional beta-amyloid. The difference is that, while that’s all Aduhelm was ever shown to do, Leqembi’s makers have already asked the FDA to give it full approval – a decision that would increase the likelihood that Medicare will cover it – based on data that show it also improves Alzheimer’s sufferer’s lives. Leqembi targets a different type of amyloid, a soluble version called “protofibrils,” and that appears to change the effect. “It can give individuals and their families three, six months longer to be participating in daily life and living independently,” says Claire Sexton, PhD, senior director of scientific programs & outreach for the Alzheimer's Association. “These types of changes matter for individuals and for their families.”
To be clear, Leqembi is not the cure Alzheimer’s researchers hope for. It does not halt or reverse the disease, and people do not get better. While the drug is the first to show clear signs of a clinical benefit, the scientific establishment is split on how much of a difference Leqembi will make in the real world. It has “a rather small effect,” wrote NIH Alzheimer’s researcher Madhav Thambisetty, MD, PhD, in an email to Leaps.org. “It is unclear how meaningful this difference will be to patients, and it is unlikely that this level of difference will be obvious to a patient (or their caregivers).” Another issue is cost: Leqembi will become available to patients later this month, but Eisai is setting the price at $26,500 per year, meaning that very few patients will be able to afford it unless Medicare chooses to reimburse them for it.
The same side effects that plagued Aduhelm are common in Leqembi treatment as well. In many patients, amyloid doesn’t just accumulate around neurons, it also forms deposits in the walls of blood vessels. Blood vessels that are shot through with amyloid are more brittle. If you infuse a drug that targets amyloid, brittle blood vessels in the brain can develop leakage that results in swelling or bleeds. Most of these come with no symptoms, and are only seen during testing, which is why they are called “imaging abnormalities.” But in situations where patients have multiple diseases or are prescribed incompatible drugs, they can be serious enough to cause death. The three deaths reported from Leqembi treatment (so far) are enough to make Thambisetty wonder “how well the drug may be tolerated in real world clinical practice where patients are likely to be sicker and have multiple other medical conditions in contrast to carefully selected patients in clinical trials.”
Porsteinsson believes that earlier detection of Alzheimer’s disease will be the next great advance in treatment, a more important step forward than Leqembi’s approval.
Still, there are reasons to be excited. A successful Alzheimer’s drug can pave the way for combination studies, in which patients try a known effective drug alongside newer, more experimental ones; or preventative studies, which take place years before symptoms occur. It also represents enormous strides in researchers’ understanding of the disease. For example, drug dosages have increased massively—in some cases quadrupling—from the early days of Alzheimer’s research. And patient selection for studies has changed drastically as well. Doctors now know that you’ve got to catch the disease early, through PET-scans or CSF tests for amyloid, if you want any chance of changing its course.
Porsteinsson believes that earlier detection of Alzheimer’s disease will be the next great advance in treatment, a more important step forward than Leqembi’s approval. His lab already uses blood tests for different types of amyloid, for different types of tau, and for measures of neuroinflammation, neural damage, and synaptic health, but commercially available versions from companies like C2N, Quest, and Fuji Rebio are likely to hit the market in the next couple of years. “[They are] going to transform the diagnosis of Alzheimer's disease,” Porsteinsson says. “If someone is experiencing memory problems, their physicians will be able to order a blood test that will tell us if this is the result of changes in your brain due to Alzheimer's disease. It will ultimately make it much easier to identify people at a very early stage of the disease, where they are most likely to benefit from treatment.”
Learn more about new blood tests to detect Alzheimer's
Early detection can help patients for more philosophical reasons as well. Betsy Groves credits finding her Alzheimer’s early with giving her the space to understand and process the changes that were happening to her before they got so bad that she couldn’t. She has been able to update her legal documents and, through her role on the Advisory Group, help the Alzheimer’s Association with developing its programs and support services for people in the early stages of the disease. She still drives, and because she and her husband love to travel, they are hoping to get out of grey, rainy Cambridge and off to Texas or Arizona this spring.
Because her Alzheimer’s disease involves amyloid deposits (a “substantial portion” do not, says Claire Sexton, which is an additional complication for research), and has not yet reached an advanced stage, Groves may be a good candidate to try Leqembi. She says she’d welcome the opportunity to take it. If she can get access, Groves hopes the drug will give her more days to be fully functioning with her husband, daughters, and three grandchildren. Mostly, she avoids thinking about what the latter stages of Alzheimer’s might be like, but she knows the time will come when it will be her reality. “So whatever lecanemab can do to extend my more productive ways of engaging with relationships in the world,” she says. “I'll take that in a minute.”
Should We Use Technologies to Enhance Morality?
Should we welcome biomedical technologies that could enhance our ability to tell right from wrong and improve behaviors that are considered immoral such as dishonesty, prejudice and antisocial aggression?
Our moral ‘hardware’ evolved over 100,000 years ago while humans were still scratching the savannah. The perils we encountered back then were radically different from those that confront us now. To survive and flourish in the face of complex future challenges our archaic operating systems might need an upgrade – in non-traditional ways.
Morality refers to standards of right and wrong when it comes to our beliefs, behaviors, and intentions. Broadly, moral enhancement is the use of biomedical technology to improve moral functioning. This could include augmenting empathy, altruism, or moral reasoning, or curbing antisocial traits like outgroup bias and aggression.
The claims related to moral enhancement are grand and polarizing: it’s been both tendered as a solution to humanity’s existential crises and bluntly dismissed as an armchair hypothesis. So, does the concept have any purchase? The answer leans heavily on our definition and expectations.
One issue is that the debate is often carved up in dichotomies – is moral enhancement feasible or unfeasible? Permissible or impermissible? Fact or fiction? On it goes. While these gesture at imperatives, trading in absolutes blurs the realities at hand. A sensible approach must resist extremes and recognize that moral disrupters are already here.
We know that existing interventions, whether they occur unknowingly or on purpose, have the power to modify moral dispositions in ways both good and bad. For instance, neurotoxins can promote antisocial behavior. The ‘lead-crime hypothesis’ links childhood lead-exposure to impulsivity, antisocial aggression, and various other problems. Mercury has been associated with cognitive deficits, which might impair moral reasoning and judgement. It’s well documented that alcohol makes people more prone to violence.
So, what about positive drivers? Here’s where it gets more tangled.
Medicine has long treated psychiatric disorders with drugs like sedatives and antipsychotics. However, there’s short mention of morality in the Diagnostic and Statistical Manual of Mental Disorders (DSM) despite the moral merits of pharmacotherapy – these effects are implicit and indirect. Such cases are regarded as treatments rather than enhancements.
It would be dangerously myopic to assume that moral augmentation is somehow beyond reach.
Conventionally, an enhancement must go beyond what is ‘normal,’ species-typical, or medically necessary – this is known as the ‘treatment-enhancement distinction.’ But boundaries of health and disease are fluid, so whether we call a procedure ‘moral enhancement’ or ‘medical treatment’ is liable to change with shifts in social values, expert opinions, and clinical practices.
Human enhancements are already used for a range of purported benefits: caffeine, smart drugs, and other supplements to boost cognitive performance; cosmetic procedures for aesthetic reasons; and steroids and stimulants for physical advantage. More boldly, cyborgs like Moon Ribas and Neil Harbisson are pushing transpecies boundaries with new kinds of sensory perception. It would be dangerously myopic to assume that moral augmentation is somehow beyond reach.
How might it work?
One possibility for shaping moral temperaments is with neurostimulation devices. These use electrodes to deliver a low-intensity current that alters the electromagnetic activity of specific neural regions. For instance, transcranial Direct Current Stimulation (tDCS) can target parts of the brain involved in self-awareness, moral judgement, and emotional decision-making. It’s been shown to increase empathy and valued-based learning, and decrease aggression and risk-taking behavior. Many countries already use tDCS to treat pain and depression, but evidence for enhancement effects on healthy subjects is mixed.
Another suggestion is targeting neuromodulators like serotonin and dopamine. Serotonin is linked to prosocial attributes like trust, fairness, and cooperation, but low activity is thought to motivate desires for revenge and harming others. It’s not as simple as indiscriminately boosting brain chemicals though. While serotonin is amenable to SSRIs, precise levels are difficult to measure and track, and there’s no scientific consensus on the “optimum” amount or on whether such a value even exists. Fluctuations due to lifestyle factors such as diet, stress, and exercise add further complexity. Currently, more research is needed on the significance of neuromodulators and their network dynamics across the moral landscape.
There are a range of other prospects. The ‘love drugs’ oxytocin and MDMA mediate pair bonding, cooperation, and social attachment, although some studies suggest that people with high levels of oxytocin are more aggressive toward outsiders. Lithium is a mood stabilizer that has been shown to reduce aggression in prison populations; beta-blockers like propranolol and the supplement omega-3 have similar effects. Increasingly, brain-computer interfaces augur a world of brave possibilities. Such appeals are not without limitations, but they indicate some ways that external tools can positively nudge our moral sentiments.
Who needs morally enhancing?
A common worry is that enhancement technologies could be weaponized for social control by authoritarian regimes, or used like the oppressive eugenics of the early 20th century. Fortunately, the realities are far more mundane and such dystopian visions are fantastical. So, what are some actual possibilities?
Some researchers suggest that neurotechnologies could help to reactivate brain regions of those suffering from moral pathologies, including healthy people with psychopathic traits (like a lack of empathy). Another proposal is using such technology on young people with conduct problems to prevent serious disorders in adulthood.
Most of us aren’t always as ethical as we would like – given the option of ‘priming’ yourself to act in consistent accord with your higher values, would you take it?
A question is whether these kinds of interventions should be compulsory for dangerous criminals. On the other hand, a voluntary treatment for inmates wouldn’t be so different from existing incentive schemes. For instance, some U.S. jurisdictions already offer drug treatment programs in exchange for early release or instead of prison time. Then there’s the difficult question of how we should treat non-criminal but potentially harmful ‘successful’ psychopaths.
Others argue that if virtues have a genetic component, there is no technological reason why present practices of embryo screening for genetic diseases couldn’t also be used for selecting socially beneficial traits.
Perhaps the most immediate scenario is a kind of voluntary moral therapy, which would use biomedicine to facilitate ideal brain-states to augment traditional psychotherapy. Most of us aren’t always as ethical as we would like – given the option of ‘priming’ yourself to act in consistent accord with your higher values, would you take it? Approaches like neurofeedback and psychedelic-assisted therapy could prove helpful.
What are the challenges?
A general challenge is that of setting. Morality is context dependent; what’s good in one environment may be bad in another and vice versa, so we don’t want to throw out the baby with the bathwater. Of course, common sense tells us that some tendencies are more socially desirable than others: fairness, altruism, and openness are clearly preferred over aggression, dishonesty, and prejudice.
One argument is that remoulding ‘brute impulses’ via biology would not count as moral enhancement. This view claims that for an action to truly count as moral it must involve cognition – reasoning, deliberation, judgement – as a necessary part of moral behavior. Critics argue that we should be concerned more with ends rather than means, so ultimately it’s outcomes that matter most.
Another worry is that modifying one biological aspect will have adverse knock-on effects for other valuable traits. Certainly, we must be careful about the network impacts of any intervention. But all stimuli have distributed effects on the body, so it’s really a matter of weighing up the cost/benefit trade-offs as in any standard medical decision.
Is it ethical?
Our values form a big part of who we are – some bioethicists argue that altering morality would pose a threat to character and personal identity. Another claim is that moral enhancement would compromise autonomy by limiting a person’s range of choices and curbing their ‘freedom to fall.’ Any intervention must consider the potential impacts on selfhood and personal liberty, in addition to the wider social implications.
This includes the importance of social and genetic diversity, which is closely tied to considerations of fairness, equality, and opportunity. The history of psychiatry is rife with examples of systematic oppression, like ‘drapetomania’ – the spurious mental illness that was thought to cause African slaves’ desire to flee captivity. Advocates for using moral enhancement technologies to help kids with conduct problems should be mindful that they disproportionately come from low-income communities. We must ensure that any habilitative practice doesn’t perpetuate harmful prejudices by unfairly targeting marginalized people.
Human capacities are the result of environmental influences, and external conditions still coax our biology in unknown ways. Status quo bias for ‘letting nature take its course’ may actually be worse long term – failing to utilize technology for human development may do more harm than good.
Then, there are concerns that morally-enhanced persons would be vulnerable to predation by those who deliberately avoid moral therapies. This relates to what’s been dubbed the ‘bootstrapping problem’: would-be moral enhancement candidates are the types of individuals that benefit from not being morally enhanced. Imagine if every senator was asked to undergo an honesty-boosting procedure prior to entering public office – would they go willingly? Then again, perhaps a technological truth-serum wouldn’t be such a bad requisite for those in positions of stern social consequence.
Advocates argue that biomedical moral betterment would simply offer another means of pursuing the same goals as fixed social mechanisms like religion, education, and community, and non-invasive therapies like cognitive-behavior therapy and meditation. It’s even possible that technological efforts would be more effective. After all, human capacities are the result of environmental influences, and external conditions still coax our biology in unknown ways. Status quo bias for ‘letting nature take its course’ may actually be worse long term – failing to utilize technology for human development may do more harm than good. If we can safely improve ourselves in direct and deliberate ways then there’s no morally significant difference whether this happens via conventional methods or new technology.
Future prospects
Where speculation about human enhancement has led to hype and technophilia, many bioethicists urge restraint. We can be grounded in current science while anticipating feasible medium-term prospects. It’s unlikely moral enhancement heralds any metamorphic post-human utopia (or dystopia), but that doesn’t mean dismissing its transformative potential. In one sense, we should be wary of transhumanist fervour about the salvatory promise of new technology. By the same token we must resist technofear and alarmist efforts to balk social and scientific progress. Emerging methods will continue to shape morality in subtle and not-so-subtle ways – the critical steps are spotting and scaffolding these with robust ethical discussion, public engagement, and reasonable policy options. Steering a bright and judicious course requires that we pilot the possibilities of morally-disruptive technologies.
Podcast: The Friday Five - your health research roundup
The Friday Five is a new series in which Leaps.org covers five breakthroughs in research over the previous week that you may have missed.
The Friday Five is a new podcast series in which Leaps.org covers five breakthroughs in research over the previous week that you may have missed. There are plenty of controversies and ethical issues in science – and we get into many of them in our online magazine – but there’s also plenty to be excited about, and this news roundup is focused on inspiring scientific work to give you some momentum headed into the weekend.
Covered in this week's Friday Five:
- Puffer fish chemical for treating chronic pain
- Sleep study on the health benefits of waking up multiples times per night
- Best exercise regimens for reducing the risk of mortality aka living longer
- AI breakthrough in mapping protein structures with DeepMind
- Ultrasound stickers to see inside your body