Reviewed by the Help Dementia Editorial Team — our editors review every article for accuracy against guidance from the National Institute on Aging, the Alzheimer’s Association, and peer-reviewed sources.
Memory test scores in Lewy body dementia typically fall lower than in many other dementia types, but the pattern of those scores tells clinicians something crucial: the decline isn’t purely about memory loss. In Lewy body dementia (LBD), patients often score between 11.4 and 16.8 on common cognitive tests—lower than they might score with Parkinson’s disease dementia, yet often with memory relatively better preserved than the loss they experience in processing speed, visual thinking, and executive function. For example, an 68-year-old woman might score 14 on the Montreal Cognitive Assessment (MoCA), placing her in moderate cognitive impairment, yet when tested specifically on memory tasks, her performance may not explain the full scope of her overall cognitive decline. This disconnect between memory scores and overall function is one of the hallmarks that helps doctors distinguish Lewy body dementia from Alzheimer’s disease.
The relationship between memory test scores and LBD diagnosis is complex because the tests themselves measure different cognitive domains. The most commonly used assessments—the Mini-Cog, MMSE (Mini-Mental State Examination), and MoCA—each capture different aspects of thinking and memory. Memory test scores alone don’t define Lewy body dementia; instead, the pattern of scores across multiple cognitive areas, combined with other clinical features like visual hallucinations and movement problems, paints the diagnostic picture. Understanding what these numbers mean—and what they don’t mean—helps families navigate diagnosis and set realistic expectations for cognitive decline.
Table of Contents
- How Do Memory Test Scores Help Identify Lewy Body Dementia?
- Understanding Test Score Ranges and What They Mean for Lewy Body Dementia
- The Distinctive Cognitive Pattern in Lewy Body Dementia
- Which Memory Tests Are Best for Detecting Lewy Body Dementia?
- Why Early Lewy Body Dementia Can Be Missed on Standard Memory Tests
- Beyond Memory: The Addenbrooke’s Cognitive Examination and Advanced Diagnostics
- What to Expect: Cognitive Decline Rates and Long-Term Trajectories
- Conclusion
How Do Memory Test Scores Help Identify Lewy Body Dementia?
memory tests serve as one window into the cognitive changes of lewy body dementia, though they’re never used alone to make a diagnosis. The most common tests administered in memory clinics include the MMSE, which has a maximum score of 30; the MoCA, also scored out of 30; and the Addenbrooke’s Cognitive Examination, which assesses memory, visuospatial function, and language. In Lewy body dementia specifically, research from Chinese memory clinics found patients averaged MMSE scores of 16.8 out of 30, compared to patients with Parkinson’s disease dementia who scored 19.5. On the MoCA, Lewy body dementia patients averaged 11.4 compared to 14.0 in Parkinson’s disease dementia. These differences, though modest, begin to suggest distinct patterns when examined alongside other test results.
What makes these scores meaningful is not the number itself, but how that number breaks down across different cognitive abilities. When doctors administer the Addenbrooke’s Cognitive Examination to someone with Lewy body dementia, they don’t just look at total score—they look at the memory-to-visuospatial ratio, which can help differentiate Lewy body dementia from Alzheimer’s disease with 82 percent sensitivity and 68 percent specificity. A patient with Alzheimer’s typically shows marked memory loss first, with relative preservation of visuospatial thinking. A patient with Lewy body dementia often shows the opposite: relatively intact memory for immediate recall, but profound difficulty with visual tasks like copying a cube or identifying objects. This pattern emerging from test scores helps steer the diagnostic process in the right direction.
Understanding Test Score Ranges and What They Mean for Lewy Body Dementia
Interpreting cognitive test scores requires knowing the threshold values that define each level of impairment. The MoCA, which is increasingly preferred over the MMSE for detecting mild cognitive changes, has these interpretation ranges: scores of 26-30 indicate normal cognition; 18-25 suggest mild cognitive impairment; 10-17 point to moderate impairment; and scores below 10 indicate severe cognitive decline. A person with Lewy body dementia averaging 11.4 on the MoCA falls squarely in the moderate impairment range, meaning they typically need assistance with many daily activities but may still recognize family members and participate in familiar routines. The same person might score differently on different days, which is itself a clue to Lewy body dementia—these patients often experience significant fluctuations in alertness and cognition, so a score of 11 one week and 9 the next is not unusual and doesn’t necessarily indicate rapid decline.
A critical limitation of relying on memory test scores alone in Lewy body dementia is that the MMSE—historically the gold standard—often misses early, subtle cognitive deficits. The MMSE includes fewer items testing executive function and visuospatial skills compared to the MoCA, meaning it can underestimate cognitive impairment in Lewy body dementia, where these areas are often affected before significant memory loss occurs. A patient in the early stages of Lewy body dementia might score 24 on the MMSE (only 6 points below normal), missing a diagnosis, while the same patient would score 16 on the MoCA, clearly in the impaired range. This is why the MoCA has largely replaced the MMSE in specialized memory clinics for dementia evaluation, particularly when Lewy body dementia is suspected.
The Distinctive Cognitive Pattern in Lewy Body Dementia
One of the most important facts about Lewy body dementia and memory test scores is that memory performance often remains relatively preserved compared to other cognitive abilities. This means a person might remember conversations from yesterday, recall their children’s names, and recognize their spouse, yet struggle profoundly to balance a checkbook, follow a complex conversation, or describe what they see in a picture. Research on prodromal (early-stage) Lewy body dementia found that while these patients did show some decline in visual recognition memory and free recall compared to healthy controls, the pattern was distinctly different from early Alzheimer’s disease. A 72-year-old man with early Lewy body dementia might score 8 points on the MMSE memory section (out of 9 possible), yet struggle with the executive function and attention items that make up the rest of the test.
The contrast between relatively preserved memory and impaired visuospatial and executive abilities stems from where Lewy bodies accumulate in the brain. In Lewy body dementia, these abnormal protein deposits first appear in the brainstem and later spread to the cortex in a pattern that affects visual processing and motor control early, and memory systems somewhat later. Over time, that pattern can shift, and memory may decline more substantially—but this relative preservation of memory, especially in the early and middle stages, is a key distinguishing feature. When reviewing test results, clinicians specifically look for whether memory scores are proportionally higher than visuoconstructive or executive function scores, which would point toward Lewy body dementia rather than Alzheimer’s disease, where memory loss typically dominates from the beginning.
Which Memory Tests Are Best for Detecting Lewy Body Dementia?
The MoCA outperforms the MMSE at detecting mild cognitive impairment overall, and this advantage holds true for Lewy body dementia specifically. Because the MoCA includes more items assessing executive function, attention, and visuospatial skills—exactly the areas that Lewy body dementia affects most—it captures cognitive changes that the MMSE might miss. Studies comparing the two tests in Parkinson’s disease and dementia with Lewy bodies found that while both tests tracked cognitive decline at similar rates over time (roughly 3.4 points per year for the MMSE), the MoCA was more sensitive to the initial, subtle deficits that appear in early Lewy body dementia. However, the MMSE does have one advantage: it is more familiar to primary care doctors and geriatricians, meaning patients are more likely to have MMSE scores available in their medical records for comparison over years.
For diagnosing Lewy body dementia specifically, some specialized clinics now use the Lewy Body Composite Risk Score (LBCRS), which combines memory test results with information about visual hallucinations, REM sleep behavior disorder, parkinsonism, and reduced dopamine transporter imaging. The LBCRS has shown remarkable discriminative ability: it achieves 96.8 percent accuracy in distinguishing Lewy body dementia from Alzheimer’s disease, with 90 percent sensitivity and 87 percent specificity. Patients with Lewy body dementia average an LBCRS of 6.1, compared to 2.4 for Alzheimer’s disease—a substantial difference. This comprehensive approach means that memory test scores are one piece of a larger diagnostic puzzle. A person evaluated in a specialized dementia clinic might receive multiple cognitive assessments over the course of a single visit, allowing clinicians to see the pattern of strengths and weaknesses rather than relying on any single test result.
Why Early Lewy Body Dementia Can Be Missed on Standard Memory Tests
The MMSE’s insensitivity to early Lewy body dementia is a well-recognized clinical problem. Because the MMSE focuses more heavily on memory and has relatively few items testing executive function, attention, and visuospatial ability, it can miss people in the early stages of Lewy body dementia who have significant impairment in these areas. Imagine a 65-year-old who is having trouble with complex reasoning and visual tasks—say, difficulty recognizing faces of people he used to know well, or problems following intricate instructions—yet performs adequately on the MMSE’s memory questions. He might score 26 on the MMSE, falling in the “normal” range by standard interpretation, when in fact he is in the early stages of Lewy body dementia. Meanwhile, the same person would score 17 or 18 on the MoCA, clearly in the impaired range.
This gap between test results can lead to months or even years of delayed diagnosis. Another reason early Lewy body dementia is sometimes missed is that memory test scores can fluctuate significantly, and clinicians unfamiliar with LBD may attribute the variation to normal day-to-day changes rather than a sign of the cognitive fluctuations characteristic of Lewy body dementia. A patient might score well on a test administered during a clear, alert morning, then perform much worse on the same test in the afternoon when drowsiness and confusion set in. Without understanding that Lewy body dementia is notorious for these fluctuations, a doctor might dismiss the poor afternoon performance as the patient not trying hard enough, rather than recognizing it as a hallmark symptom. This is why a comprehensive cognitive evaluation for suspected Lewy body dementia should include observations from family members about the patient’s typical day-to-day cognition and alertness, not just test scores from a single clinic visit.
Beyond Memory: The Addenbrooke’s Cognitive Examination and Advanced Diagnostics
The Addenbrooke’s Cognitive Examination (ACE) is a comprehensive test that many specialized clinics prefer over the MMSE because it provides a more detailed breakdown of cognitive abilities, including memory, attention, fluency, language, and visuospatial function. Research on the revised ACE found that the ratio of memory score to visuospatial score could differentiate Lewy body dementia from Alzheimer’s disease with 82 percent sensitivity, 68 percent specificity, and 77 percent mean accuracy.
This ratio works because, as noted, Lewy body dementia typically spares memory while affecting visuospatial abilities, creating a distinctive pattern: a patient might score 18 on the memory subtest but only 8 on the visuospatial subtest, whereas an Alzheimer’s patient would show lower scores on both. A 70-year-old woman presenting with visual hallucinations and difficulty with drawing tasks might have an ACE memory subscale score of 19 out of 26, but a visuospatial score of 7 out of 16, which is exactly the pattern clinicians look for in Lewy body dementia.
What to Expect: Cognitive Decline Rates and Long-Term Trajectories
Once Lewy body dementia is diagnosed based on memory test scores and clinical features, families often ask how quickly the condition will progress. Research comparing cognitive decline rates found that Lewy body dementia and Alzheimer’s disease decline at remarkably similar rates: Lewy body dementia patients averaged 3.4 MMSE points of decline per year, compared to 3.3 points per year for Alzheimer’s disease—no statistically significant difference across six different studies. However, this similarity in overall decline rate masks important differences in where that decline occurs.
In Lewy body dementia, if memory was initially relatively preserved while visuospatial and executive functions were more impaired, over time those initially preserved areas may remain somewhat better than in Alzheimer’s disease, even as the total decline continues. A person with Lewy body dementia might maintain better conversational memory than someone with Alzheimer’s at the same overall functional level, but that preserved memory doesn’t necessarily make the condition easier to live with, because the severe visuospatial and executive dysfunction persists. Understanding this pattern helps families anticipate what kinds of support their loved one will need and which abilities might be worth trying to preserve through cognitive and physical engagement.
Conclusion
Memory test scores provide valuable information about Lewy body dementia, but they must be interpreted carefully and in context. The typical memory test scores for Lewy body dementia—averaging 11.4 on the MoCA and 16.8 on the MMSE—reflect moderate cognitive impairment, but these numbers alone don’t capture the distinctive pattern of cognitive change that characterizes the condition. What matters most is not any single score, but how memory performance compares to visuospatial and executive function, how scores fluctuate from day to day, and how test results align with clinical features like visual hallucinations and movement problems. The MoCA is generally superior to the MMSE for detecting early Lewy body dementia, and specialized tests like the Addenbrooke’s Cognitive Examination and the Lewy Body Composite Risk Score provide even more diagnostic precision. If you’ve received memory test scores as part of a possible Lewy body dementia diagnosis, the most important step is to ensure evaluation by a neurologist or memory specialist experienced with Lewy body dementia.
Ask specifically about the pattern of your scores across different cognitive domains, not just the overall number. Request the MoCA rather than only the MMSE if you haven’t had that assessment. Document any patterns of fluctuation in alertness and cognition that you observe at home, as this information helps clinicians distinguish Lewy body dementia from other conditions. Finally, remember that a diagnosis made by memory test scores alone is incomplete; the clinical picture—including hallucinations, parkinsonian features, and REM sleep behavior—must also fit the pattern. Memory tests are a starting point, not the full story.
