{"product_id":"donanemab-continues-to-show-benefits-at-3-years-for-people-with-early-symptomatic-alzheimers-disease","title":"Donanemab Continues to Show Benefits at 3 Years for People with Early Symptomatic Alzheimer's Disease","description":"\u003cp\u003eIn a large long-term extension of the landmark TRAILBLAZER-ALZ 2 trial, researchers found that people with early symptomatic Alzheimer's disease who received the amyloid-clearing drug donanemab showed continued and even increasing clinical benefits over 3 years. Those who started donanemab early had 1.2 points less decline on a standard dementia rating scale than a similar untreated comparison group, and starting early also reduced the risk of advancing to the next stage of the disease by 27% compared with starting later. Importantly, most participants were able to stop treatment once their brain amyloid plaques reached very low levels, and no new safety concerns emerged. These results suggest that a limited course of therapy may offer lasting benefits for people treated at the earliest stages of Alzheimer's disease.\u003c\/p\u003e\n\n\u003ch1\u003eDonanemab Continues to Show Benefits at 3 Years for People with Early Symptomatic Alzheimer's Disease\u003c\/h1\u003e\n\n\u003ch2\u003eTable of Contents\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"#ddn-key-points\"\u003eKey Points\u003c\/a\u003e\u003c\/li\u003e\n\n  \u003cli\u003e\u003ca href=\"#background\"\u003eWhy This Research Matters\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#study-design\"\u003eHow the Study Was Designed\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#participants\"\u003eWho Participated in the Study\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#comparison-group\"\u003eThe External Comparison Group (ADNI)\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#key-findings\"\u003eKey Findings at 3 Years\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#early-vs-delayed\"\u003eStarting Early vs. Starting Later\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#amyloid-clearance\"\u003eAmyloid Plaque Clearance and Reaccumulation\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#safety\"\u003eSafety Profile: No New Signals\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#clinical-implications\"\u003eWhat This Means for Patients\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#limitations\"\u003eStudy Limitations\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#recommendations\"\u003eRecommendations for Patients and Families\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#ddn-faq\"\u003eFrequently Asked Questions\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"#source\"\u003eSource Information\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c!-- ddn:keypoints:start --\u003e\n\u003ch2 id=\"ddn-key-points\"\u003eKey Points\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eIn a 3-year extension of a clinical trial, donanemab slowed decline by 1.2 points on the CDR-SB versus an untreated comparison group.\u003c\/li\u003e\n\u003cli\u003eStarting donanemab early reduced the risk of Alzheimer's disease progression by 27% compared with starting 18 months later.\u003c\/li\u003e\n\u003cli\u003eMost participants stopped donanemab after achieving very low amyloid levels, and no new safety concerns emerged over 3 years.\u003c\/li\u003e\n\u003cli\u003ePredicted amyloid reaccumulation after stopping treatment was about 2.4 Centiloids per year, suggesting lasting benefit from limited dosing.\u003c\/li\u003e\n\u003cli\u003eThe long-term extension used an external ADNI control group, and analyses were exploratory, so results should be interpreted cautiously.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- ddn:keypoints:end --\u003e\n\n\n\u003ch2 id=\"background\"\u003eWhy This Research Matters\u003c\/h2\u003e\n\u003cp\u003eAlzheimer's disease (AD) is a progressive brain disorder that causes memory loss and thinking problems. It is marked by the buildup of two abnormal proteins in the brain: β-amyloid plaques (sticky clumps of protein between nerve cells) and neurofibrillary tangles (twisted strands of tau protein inside cells). Over time, these proteins damage brain tissue and lead to progressive cognitive decline.\u003c\/p\u003e\n\u003cp\u003ePrevious randomized controlled trials have shown that removing enough amyloid plaque can slow the disease's progression. Donanemab is an antibody therapy that targets and clears these amyloid plaques. In the main phase 3 trial, called TRAILBLAZER-ALZ 2, donanemab significantly slowed clinical decline compared with placebo over 76 weeks (about 18 months) in people with early symptomatic Alzheimer's disease who had both amyloid and tau pathology.\u003c\/p\u003e\n\u003cp\u003eA unique feature of this trial was its \"limited-duration dosing\" approach. Once a person's amyloid plaques dropped below a certain level, they were switched—without knowing it—to placebo (inactive saline) infusions. This was built into the study intentionally to avoid unnecessary ongoing treatment and to reduce costs for future patients.\u003c\/p\u003e\n\u003cp\u003eBut important questions remained: Do the benefits last beyond the initial 18-month period? Does starting treatment earlier make a meaningful difference compared to starting later? And is it safe to stop treatment once amyloid is cleared? This long-term extension (LTE) study was designed to answer those questions.\u003c\/p\u003e\n\n\u003ch2 id=\"study-design\"\u003eHow the Study Was Designed\u003c\/h2\u003e\n\u003cp\u003ePeople who completed the initial 76-week, placebo-controlled phase of TRAILBLAZER-ALZ 2 were eligible to continue into an additional 78-week (about 18-month) long-term extension period. This extension was \"blinded,\" meaning neither the participants nor the study investigators knew who was receiving the real drug versus placebo. The trial is registered at ClinicalTrials.gov under identifier NCT04437511.\u003c\/p\u003e\n\u003cp\u003eParticipants were originally assigned at random in a 1:1 ratio to receive either donanemab or placebo. Donanemab was given as an intravenous (IV) infusion every 4 weeks at a dose of 700 mg for the first three doses, then 1400 mg for subsequent doses.\u003c\/p\u003e\n\u003cp\u003eDuring the placebo-controlled period, participants receiving donanemab could be switched—again blindly—to placebo at week 24 or week 52 if they met \"treatment course completion criteria.\" These criteria were met when amyloid plaque levels dropped below 11 Centiloids (CL; a unit for measuring amyloid on a brain scan) on any single PET scan, or below 25 CL on two consecutive PET scans.\u003c\/p\u003e\n\u003cp\u003eThe study used two groups for comparison. The \u003cstrong\u003e\"early-start\" group\u003c\/strong\u003e consisted of 860 participants who were originally assigned to donanemab. Of these, some met the completion criteria and were switched to placebo infusions, while others who had not yet reached very low amyloid levels continued receiving donanemab into the extension period. The \u003cstrong\u003e\"delayed-start\" group\u003c\/strong\u003e consisted of participants who were originally assigned to placebo during the first 76 weeks, then began receiving donanemab in the extension period, following the same dose schedule.\u003c\/p\u003e\n\u003cp\u003eParticipants in the delayed-start group could be switched to placebo if they met the completion criteria at week 102 or 130 of the study. This design allowed researchers to compare what happens when treatment starts early versus when it is delayed by about 18 months.\u003c\/p\u003e\n\u003cp\u003eThe trial was conducted at 277 centers across eight countries: Australia, Canada, the Czech Republic, Japan, the Netherlands, Poland, the United Kingdom, and the United States. All procedures were approved by institutional review committees, and all participants and their study partners gave written informed consent.\u003c\/p\u003e\n\n\u003ch2 id=\"participants\"\u003eWho Participated in the Study\u003c\/h2\u003e\n\u003cp\u003eTo enter the original placebo-controlled period, participants had to be between 60 and 85 years old. They needed a score of 20 to 28 on the Mini-Mental State Examination (MMSE; a 30-point cognitive screening test, where lower scores indicate greater impairment). They also had to have confirmed amyloid pathology, defined as at least 37 CL on a PET scan using florbetapir or florbetaben tracers, and evidence of tau pathology on a separate flortaucipir PET scan.\u003c\/p\u003e\n\u003cp\u003ePeople were excluded if they had certain brain imaging abnormalities. These included amyloid-related imaging abnormalities of the edema\/effusion type (ARIA-E; swelling in the brain linked to amyloid-clearing drugs), more than four cerebral microhemorrhages (tiny bleeds in the brain), more than one area of superficial siderosis (surface iron deposits from previous bleeding), any intracerebral hemorrhage larger than 1 cm, or severe white matter disease on MRI.\u003c\/p\u003e\n\u003cp\u003eNo additional eligibility hurdles were required to move from the placebo-controlled period into the extension. Notably, participants did not need to repeat the screening tests—they simply continued if they had completed the first phase.\u003c\/p\u003e\n\u003cp\u003eHere is what happened to the participants, in concrete numbers:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e860 people were originally randomized to donanemab (the early-start group). Of these, 550 (64.0%) received at least one infusion during the extension period.\u003c\/li\u003e\n  \u003cli\u003eAmong those 550, 393 had already met treatment completion criteria and had been switched to placebo infusions at week 24, 52, or 76. The remaining 157 continued receiving donanemab into the extension period because their amyloid levels had not yet dropped low enough.\u003c\/li\u003e\n  \u003cli\u003e876 people were originally randomized to placebo. Of these, 657 (75.0%) entered the extension and began receiving donanemab—this became the delayed-start group.\u003c\/li\u003e\n  \u003cli\u003eCompletion rates in the extension were 74.3% for early-start participants who had switched to placebo, 81.5% for early-start participants who continued on donanemab, and 72.3% for delayed-start participants.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eBy the end of the extension period, most infusions given in both groups were actually placebo, because so many people had already achieved the very low amyloid levels that triggered treatment completion.\u003c\/p\u003e\n\u003cp\u003eResearchers also compared participant characteristics at the start of the extension. Among early-start participants, those who finished treatment by week 76 were more often female (58.3% versus 51.0%) and less often carried two copies of the APOE ε4 risk gene (11.5% versus 25.5%), compared with those who continued donanemab. The participants who continued donanemab also started with higher amyloid levels: 122.0 CL (standard deviation [SD] 34.8) at screening versus 94.8 CL (SD 31.6), and 37.5 CL (SD 21.1) at the start of the extension versus 3.7 CL (SD 11.3).\u003c\/p\u003e\n\u003cp\u003eDelayed-start participants were more likely to be taking symptomatic Alzheimer's medications (acetylcholinesterase inhibitors and\/or memantine: 68.0% versus 60.6%) than early-start participants were at their original baseline, reflecting their slightly more advanced disease state. Their MMSE scores also suggested greater cognitive impairment at the time they began donanemab.\u003c\/p\u003e\n\n\u003ch2 id=\"comparison-group\"\u003eThe External Comparison Group (ADNI)\u003c\/h2\u003e\n\u003cp\u003eBecause the extension period did not include an internal placebo group, the researchers needed another way to estimate what would have happened to participants without treatment. They turned to the Alzheimer's Disease Neuroimaging Initiative (ADNI), a large public-private research partnership launched in 2003 under principal investigator Michael W. Weiner, MD.\u003c\/p\u003e\n\u003cp\u003eADNI was created to test whether brain imaging methods—like serial MRI and PET scans—along with other biological markers and clinical assessments, could track the progression of mild cognitive impairment and early Alzheimer's disease. Its ongoing goals include validating biomarkers, increasing diversity in research cohorts, and sharing data with the scientific community.\u003c\/p\u003e\n\u003cp\u003eFrom 2,430 ADNI participants evaluated, 534 met the eligibility criteria for this comparison. These individuals represented an \"amyloid-targeting therapy–naïve\" population, meaning they had never received amyloid-clearing treatment. They were required to have cognitive impairment and a cerebrospinal fluid total tau-to-amyloid β42 ratio above 0.28, which is an established biological indicator of amyloid pathology.\u003c\/p\u003e\n\u003cp\u003eTo make a fair comparison, the researchers used a statistical technique called propensity score weighting. This method mathematically balances the treatment groups and the external control group on important baseline characteristics, including age, sex, APOE ε4 status, CDR-SB score, ADAS-Cog13 score, and screening MMSE score. After weighting, the effective sample size was 268 for comparisons with the early-start group and 301 for comparisons with the delayed-start group.\u003c\/p\u003e\n\u003cp\u003eOne important detail: baseline amyloid levels were not adjusted for, because this information was missing for 43% of the ADNI participants. The researchers checked that all covariates were well balanced after weighting (standardized mean difference under 0.10 for each) and trimmed extreme weights to the 95th percentile. They also confirmed that the weighted ADNI control group closely tracked the disease trajectory of the original TRAILBLAZER-ALZ 2 placebo group, which suggests it served as an appropriate stand-in for untreated disease progression.\u003c\/p\u003e\n\n\u003ch2 id=\"key-findings\"\u003eKey Findings at 3 Years\u003c\/h2\u003e\n\u003cp\u003eThe primary measure of effectiveness in the extension was the change from baseline in the Clinical Dementia Rating Scale–Sum of Boxes (CDR-SB) score. The CDR-SB is a well-established scale that rates both cognition (thinking) and function (daily activities). It ranges from 0 to 18, with higher scores indicating greater impairment.\u003c\/p\u003e\n\u003cp\u003eThe headline result is this: after 3 years (154 weeks), early-start participants who received donanemab showed significantly slower disease progression than the weighted ADNI control group. The adjusted mean difference was \u003cstrong\u003e−1.2 points on the CDR-SB\u003c\/strong\u003e (95% confidence interval [CI], −1.7 to −0.7). In plain terms, the untreated comparison group declined about 1.2 points more on this 18-point scale than the treated group did.\u003c\/p\u003e\n\u003cp\u003eDelayed-start participants also benefited. At 76 weeks after they first began donanemab, they showed a CDR-SB treatment difference of \u003cstrong\u003e−0.8 points\u003c\/strong\u003e versus the weighted ADNI control (95% CI, −1.3 to −0.3).\u003c\/p\u003e\n\u003cp\u003eImportantly, participants who completed their course of donanemab treatment by week 52—meaning they achieved very low amyloid levels quickly—showed similar slowing of disease progression at the 3-year mark as the overall early-start group. This suggests that a relatively short course of treatment can produce durable benefits.\u003c\/p\u003e\n\u003cp\u003eResearchers also calculated \"relative time savings\" by comparing how long it took the treated group to reach the same level of decline as the untreated group. Using this model, they back-calculated the ADNI timepoint corresponding to the 36-month average of the early-start group to estimate how much clinical decline was delayed or avoided. The magnitude of the treatment benefit appeared to grow over time rather than shrink, which the authors describe as \"increasing clinical benefits\" across 3 years.\u003c\/p\u003e\n\u003cp\u003eAll analyses in the extension were exploratory, meaning they were not pre-specified as confirmatory tests and were not adjusted for multiple comparisons. Still, the consistency of the findings across different measures and time points supports their credibility.\u003c\/p\u003e\n\n\u003ch2 id=\"early-vs-delayed\"\u003eStarting Early vs. Starting Later\u003c\/h2\u003e\n\u003cp\u003eOne of the most clinically meaningful questions the study addressed is whether the timing of treatment matters. To answer this, the researchers compared the early-start and delayed-start groups directly, looking at the risk of progressing to the next stage of Alzheimer's disease.\u003c\/p\u003e\n\u003cp\u003eDisease stage was measured with the CDR–Global (CDR-G) score, which ranges from 0 (no dementia) to 3 (severe dementia). \"Progression to the next clinical stage\" was defined as an increase in the CDR-G score at two consecutive visits, which participants attended every 3 months.\u003c\/p\u003e\n\u003cp\u003eThe results favored early treatment. Over 3 years, early-start participants had a significantly lower risk of disease progression compared with delayed-start participants: \u003cstrong\u003ehazard ratio = 0.73 (p \u0026lt; 0.001)\u003c\/strong\u003e. A hazard ratio of 0.73 means the early-start group was about 27% less likely to advance to a more severe stage of Alzheimer's during the study period than the delayed-start group. The p-value of less than 0.001 means there is less than a 0.1% probability that this difference occurred by chance.\u003c\/p\u003e\n\u003cp\u003eThis finding has a direct practical implication: it supports the idea that intervening at the earliest point of symptoms gives patients the best chance of preserving their current level of function for longer. Waiting—even by roughly 18 months—appears to leave patients at a measurable disadvantage.\u003c\/p\u003e\n\n\u003ch2 id=\"amyloid-clearance\"\u003eAmyloid Plaque Clearance and Reaccumulation\u003c\/h2\u003e\n\u003cp\u003eThe study also tracked what happened to amyloid plaques in the brain over time, using PET scans at weeks 102, 130, and 154. Researchers assessed both how effectively donanemab cleared amyloid and whether plaques grew back after treatment stopped.\u003c\/p\u003e\n\u003cp\u003eRegarding clearance, more than \u003cstrong\u003e75% of participants in both the early-start and delayed-start groups\u003c\/strong\u003e achieved amyloid clearance—defined as plaque levels below 24.1 CL—when measured 76 weeks after they first began donanemab treatment. A level below 24.1 CL corresponds closely to a \"negative\" scan by visual reading, meaning the brain no longer shows the elevated amyloid signal typical of Alzheimer's disease.\u003c\/p\u003e\n\u003cp\u003eRegarding reaccumulation, the researchers combined data from this study with data from three other donanemab trials: a phase 1b study (NCT02624778), the phase 2 TRAILBLAZER-ALZ trial (NCT03367403), the phase 2 TRAILBLAZER-EXT extension (NCT04640077), and the TRAILBLAZER-ALZ 2 placebo-controlled portion and safety addendum. Using an established exposure-response model, they predicted a median amyloid reaccumulation rate of \u003cstrong\u003e2.4 Centiloids per year\u003c\/strong\u003e among participants who had met treatment completion criteria by week 52.\u003c\/p\u003e\n\u003cp\u003eTo put that number in perspective, consider that study participants entered with amyloid levels of about 90 to 122 CL, and treatment brought them below 24.1 CL. At a reaccumulation rate of roughly 2.4 CL per year, it would take many years—likely well over a decade—for plaques to climb back to the levels seen at diagnosis. This explains why a limited course of treatment could provide lasting benefit without continuous dosing.\u003c\/p\u003e\n\n\u003ch2 id=\"safety\"\u003eSafety Profile: No New Signals\u003c\/h2\u003e\n\u003cp\u003eSafety was monitored throughout the extension period using adverse event (AE) reporting and centrally read MRI scans. The researchers reported that \u003cstrong\u003eno new safety signals were observed\u003c\/strong\u003e compared with the established safety profile of donanemab from earlier phases of the program.\u003c\/p\u003e\n\u003cp\u003eParticular attention was paid to amyloid-related imaging abnormalities (ARIA), which are a known class of side effects with amyloid-clearing antibodies. ARIA-E refers to swelling or fluid accumulation in the brain, which can usually be detected on MRI before it causes symptoms. The researchers analyzed the time to the first ARIA-E event based on MRI findings or a cluster of related symptoms, covering the treatment period and extending to 57 days after the last dose.\u003c\/p\u003e\n\u003cp\u003eBecause donanemab is given in a limited course, the study also specifically assessed whether new ARIA events could appear after dosing had already finished. They tracked new ARIA events at 6-month intervals, with the first interval starting 58 days after the last donanemab dose. They also calculated an observation time-adjusted incidence rate (OAIR) for participants who completed treatment by week 52; this rate adjusts for the fact that different participants were observed for different lengths of time, making the comparison fairer. The details of these analyses support the conclusion that the risk of ARIA is primarily linked to active dosing and does not meaningfully increase after treatment stops.\u003c\/p\u003e\n\n\u003ch2 id=\"clinical-implications\"\u003eWhat This Means for Patients\u003c\/h2\u003e\n\u003cp\u003eThese findings carry several practical messages for people living with early symptomatic Alzheimer's disease and their families.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFirst, the benefits of donanemab extend well beyond the initial treatment period.\u003c\/strong\u003e The 1.2-point difference on the CDR-SB at 3 years represents a meaningful slowing of decline in thinking and daily function. A difference of this size on an 18-point scale can translate into months of preserved independence—time during which a person can continue managing finances, driving, cooking, or enjoying family activities.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSecond, earlier treatment appears to be better.\u003c\/strong\u003e The 27% lower risk of progressing to a more advanced disease stage among early-start participants (hazard ratio 0.73, p \u0026lt; 0.001) is a strong argument for seeking evaluation promptly when memory or thinking symptoms first appear. Many people delay seeing a doctor because they attribute early changes to normal aging. This study suggests those months of delay can matter.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThird, limited-duration dosing is feasible.\u003c\/strong\u003e More than three-quarters of participants achieved amyloid clearance within about 18 months of starting treatment. The slow predicted reaccumulation rate of 2.4 Centiloids per year means most people will not need continuous infusions for life. This has practical advantages: fewer medical visits, lower cumulative cost, and less burden on patients and caregivers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFourth, the safety profile is reassuring.\u003c\/strong\u003e No new safety concerns emerged after up to 3 years of follow-up. The known risks—particularly ARIA—were manageable and were not observed to spike after treatment stopped.\u003c\/p\u003e\n\u003cp\u003eIt is worth emphasizing that participants who completed treatment by week 52—those with the most robust early response—enjoyed similar long-term benefits to the overall treated group. This suggests that rapid responders can stop therapy relatively quickly without sacrificing efficacy.\u003c\/p\u003e\n\n\u003ch2 id=\"limitations\"\u003eStudy Limitations\u003c\/h2\u003e\n\u003cp\u003eSeveral limitations should be kept in mind when interpreting these results.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThere was no internal placebo group in the extension period.\u003c\/strong\u003e Because all participants in the extension received donanemab at some point (either continuing it or starting it as delayed-start), the researchers could not compare against a group that never received the drug during the same timeframe. Instead, they relied on an external control cohort from the ADNI database. Although the ADNI cohort was carefully matched using propensity score weighting and validated against the original placebo trajectory, external comparisons can never be as robust as a concurrent randomized placebo group. Unmeasured differences between the study populations could theoretically influence the results.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAll extension analyses were exploratory.\u003c\/strong\u003e They were not pre-specified as primary confirmatory tests and were not controlled for multiplicity. This means the statistical findings, while suggestive and consistent, do not carry the same evidentiary weight as the original 76-week primary analysis.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eBaseline amyloid levels were not included in the weighting model\u003c\/strong\u003e because they were missing for 43% of the ADNI participants. Since amyloid burden influences disease trajectory, this is a potential source of residual confounding.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe study population was not fully representative of all Alzheimer's patients.\u003c\/strong\u003e Participants had \"early symptomatic\" disease, relatively high MMSE scores (20 to 28), and confirmed amyloid and tau pathology. People with more advanced dementia, atypical presentations, or significant vascular disease on MRI were excluded. Results may not generalize to those groups.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSelective dropout is a concern in any long-term study.\u003c\/strong\u003e Participants who remained in the extension through 3 years may differ from those who left, potentially biasing the results. The researchers report completion rates (74.3% to 81.5% across groups), but the characteristics of dropouts were not fully explored in this report.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFinally, the reaccumulation rate of 2.4 Centiloids per year is a model-based prediction, not a direct long-term observation.\u003c\/strong\u003e It incorporates data from several studies and assumes the model structure is correct. Actual reaccumulation in individual patients will vary, and long-term monitoring beyond 3 years is still needed to know how often people will eventually need retreatment.\u003c\/p\u003e\n\n\u003ch2 id=\"recommendations\"\u003eRecommendations for Patients and Families\u003c\/h2\u003e\n\u003cp\u003eBased on this study, here are actionable points to discuss with a healthcare provider:\u003c\/p\u003e\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDo not ignore early symptoms.\u003c\/strong\u003e If you or a loved one are experiencing memory lapses, difficulty finding words, trouble with planning, or changes in judgment, seek a thorough evaluation sooner rather than later. This study shows that the timing of treatment initiation is linked to long-term outcomes.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAsk about biomarker testing.\u003c\/strong\u003e A diagnosis of Alzheimer's disease should be confirmed with biomarkers—amyloid PET scans, cerebrospinal fluid testing, or blood-based tests—before considering amyloid-targeting therapies like donanemab. This study required confirmed amyloid pathology of at least 37 CL and evidence of tau pathology for entry.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDiscuss the full risk-benefit profile.\u003c\/strong\u003e Donanemab is associated with ARIA, which can occasionally cause serious brain swelling or bleeding. The risk is higher in people who carry the APOE ε4 gene, particularly those with two copies. MRI monitoring during treatment is essential. Ask your doctor about your individual risk based on your genetic status and baseline brain imaging.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePlan for a limited treatment course.\u003c\/strong\u003e Unlike many chronic disease medications, donanemab is not necessarily a lifelong therapy. In this study, participants stopped after achieving amyloid clearance (below 24.1 CL on PET). Ask your care team how your response will be monitored and what the plan is for stopping or potentially restarting treatment.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eConsider the practical logistics.\u003c\/strong\u003e Donanemab requires intravenous infusions every 4 weeks, at least initially, along with periodic MRI scans to monitor for ARIA. Plan for transportation, time off work, and caregiver support for these appointments.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eContinue standard Alzheimer's care.\u003c\/strong\u003e Many participants in this study were also taking symptomatic medications (acetylcholinesterase inhibitors or memantine). Donanemab is intended to modify the underlying disease process, not to replace other treatments that help manage symptoms.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExpect reaccumulation to be slow—but monitor.\u003c\/strong\u003e Based on the predicted rate of 2.4 Centiloids per year, it may take many years for amyloid to return to diagnostic levels. However, individual rates vary, and periodic follow-up imaging or clinical assessments may be recommended to determine if and when retreatment is needed.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003c!-- ddn:faq:start --\u003e\n\u003ch2 id=\"ddn-faq\"\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003ch3\u003eWho can be considered for donanemab treatment based on this study?\u003c\/h3\u003e\n\u003cp\u003ePeople aged 60 to 85 with early symptomatic Alzheimer's disease, confirmed amyloid plaques on PET scan, and evidence of tau pathology. They needed Mini-Mental State Examination scores between 20 and 28. People with certain brain imaging abnormalities, like significant swelling, bleeding, or severe white matter disease, were excluded from the trial.\u003c\/p\u003e\n\u003ch3\u003eWhat does a 1.2-point difference on the CDR-SB scale mean for patients?\u003c\/h3\u003e\n\u003cp\u003eThe Clinical Dementia Rating Scale–Sum of Boxes measures thinking and daily function from 0 to 18, with higher scores meaning worse impairment. After 3 years, treated patients declined about 1.2 points less than an untreated comparison group. That difference can translate into months of preserved independence in activities like managing finances, driving, or cooking.\u003c\/p\u003e\n\u003ch3\u003eIs it better to start donanemab early rather than later?\u003c\/h3\u003e\n\u003cp\u003eYes. In this 3-year extension study, people who started donanemab early had a 27% lower risk of progressing to a more advanced stage of Alzheimer's disease compared to those whose treatment was delayed by about 18 months. The hazard ratio was 0.73, meaning early treatment significantly reduced disease progression risk.\u003c\/p\u003e\n\u003ch3\u003eWhat are the main risks or side effects of donanemab?\u003c\/h3\u003e\n\u003cp\u003eThe main known side effect is amyloid-related imaging abnormalities (ARIA), which can include brain swelling or small bleeds. ARIA can usually be seen on MRI before causing symptoms. In this 3-year extension, no new safety concerns appeared, and ARIA risk was mainly linked to active treatment, not after stopping. Regular MRI monitoring is essential.\u003c\/p\u003e\n\u003ch3\u003eWhat is the amyloid reaccumulation rate after stopping donanemab?\u003c\/h3\u003e\n\u003cp\u003eResearchers predicted a median reaccumulation rate of about 2.4 Centiloids per year in people who completed treatment early. Study participants started with amyloid levels around 90 to 122 CL and were brought below 24.1 CL. At this slow rate, it would likely take many years for plaques to reach diagnosis-level amounts again.\u003c\/p\u003e\n\u003ch3\u003eWere there limitations to this long-term extension study?\u003c\/h3\u003e\n\u003cp\u003eYes. There was no internal placebo group during the extension, so researchers used an external comparison group from the ADNI database. All extension analyses were exploratory, not pre-specified. Baseline amyloid levels were missing for many ADNI participants, and the study population was limited to early symptomatic Alzheimer's patients, so results may not apply to everyone.\u003c\/p\u003e\n\u003ch3\u003eShould I get a second opinion before starting donanemab for early symptomatic Alzheimer's disease?\u003c\/h3\u003e\n\u003cp\u003eBefore starting donanemab, a second opinion can help confirm that Alzheimer's disease is truly early symptomatic and biomarker-positive, since eligibility requires amyloid and tau evidence. In a large long-term study, catching the disease earlier mattered: early-start patients had a 27% lower risk of progressing to the next disease stage than those starting about 18 months later, and untreated controls declined 1.2 more points on the CDR-SB scale over three years. Donanemab is given by infusion every 4 weeks, is stopped once amyloid plaques fall very low, and carries ARIA risks that are higher in APOE e4 carriers, so careful individual risk-benefit review is essential before committing. Diagnostic Detectives Network provides independent expert second opinions.\u003c\/p\u003e\n\u003c!-- ddn:faq:end --\u003e\n\n\u003ch2 id=\"source\"\u003eSource Information\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eOriginal article title:\u003c\/strong\u003e Donanemab in early symptomatic Alzheimer's disease TRAILBLAZER-ALZ 2 long-term extension - 2026\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors:\u003c\/strong\u003e Jennifer A. Zimmer, John R. Sims, Cynthia D. Evans, Emel Serap Monkul Nery, Hong Wang, Alette M. Wessels, Giulia Tronchin, Shoichiro Sato, Lars Lau Raket, Scott W. Andersen, Christophe Sapin, Marie-Ange Paget, Ivelina Gueorguieva, Paul Ardayfio, Rashna Khanna, Dawn A. Brooks, Brandy R. Matthews, Mark A. Mintun, for the Alzheimer's Disease Neuroimaging Initiative\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAffiliation:\u003c\/strong\u003e Eli Lilly and Company, Indianapolis, IN, USA\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJournal:\u003c\/strong\u003e The Journal of Prevention of Alzheimer's Disease, Volume 13 (2026), Article 100446\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePublication details:\u003c\/strong\u003e Received October 10, 2025; revised November 16, 2025; accepted November 17, 2025; available online December 1, 2025. Open access under the CC BY license.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration:\u003c\/strong\u003e ClinicalTrials.gov identifier NCT04437511\u003c\/p\u003e\n\u003cp\u003eThis patient-friendly article is based on peer-reviewed research. It is intended for educational purposes and is not a substitute for individualized medical advice from a qualified healthcare professional. Always discuss treatment options, including risks and benefits, with your doctor.\u003c\/p\u003e","brand":"DiagnosticDetectives.Com","offers":[{"title":"Default Title","offer_id":47549377544348,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true}],"url":"https:\/\/diagnosticdetectives.com\/ar\/products\/donanemab-continues-to-show-benefits-at-3-years-for-people-with-early-symptomatic-alzheimers-disease","provider":"DiagnosticDetectives.Com","version":"1.0","type":"link"}