Dementia With Lewy Bodies: Clinical Symptoms, Biomarkers and Progression

Primary outcomes

1. Cerebrospinal fluid amyloid-beta 1-42

   Time frame: Data for this outcome are collected at baseline.

   Cerebrospinal fluid (CSF) amyloid-beta 1-42 was coded as normal/abnormal/unknown based on centre-specific cutoffs. CSF samples were obtained from the Karolinska Institutet GEDOC Biobank (Stockholm, Sweden).

2. Cerebrospinal fluid phosphorylated tau 181

   Time frame: Data for this outcome are collected at baseline.

   Cerebrospinal fluid (CSF) phosphorylated tau 181 was coded as normal/abnormal/unknown based on centre-specific cutoffs. CSF samples were obtained from the Karolinska Institutet GEDOC Biobank (Stockholm, Sweden).

3. DaT-Scan

   Time frame: Data for this outcome are collected at baseline.

   Dopamine transporter scan (DaT-Scan) was coded as normal/abnormal/unknown based on visual assessment as per established diagnostic criteria.

4. MRI

   Time frame: Data for this outcome are collected at baseline.

   Magnetic Resonance Imaging (MRI) images were coded as normal/abnormal/unknown based on visual assessment as per established diagnostic criteria.

5. EEG

   Time frame: Data for this outcome are collected at baseline.

   Electroencephalography (EEG) was coded as normal/abnormal/unknown based on visual assessment as per established diagnostic criteria.

6. FDG-PET

   Time frame: Data for this outcome are collected at baseline.

   Fluorodeoxyglucose-Positron Emission Topography (FDG-PET) was coded as normal/abnormal/unknown based on visual assessment as per established diagnostic criteria.

7. RAVLT

   Time frame: Within 6 months of participants receiving their final diagnosis.

   Rey Auditory Verbal Learning Test (RAVLT) was used to assess memory, with participants' scores recorded across five learning trials. Total scores ranged from 0 to 75, with a maximum raw score of 15 per trial. Higher scores indicate better memory performance.

8. RAVLT delayed recall

   Time frame: Within 6 months of participants receiving their final diagnosis.

   Rey Auditory Verbal Learning Test (RAVLT) delayed recall assesses participants' memory based on the number of words recalled from a 15-word list after 30 minutes of learning. Total scores can thus range from 0 to 15. Higher scores indicate better memory performance.

9. RCFT copy

   Time frame: Within 6 months of participants receiving their final diagnosis.

   Rey Complex Figure Test (RCFT) copy was used to assess participants' visuospatial abilities. Performance is evaluated based on the reproduction of 18 figure elements, each scored on a scale from 0 to 2 (0 = incorrectly placed/absent; 0.5 = inaccurately drawn/incorrectly placed but recognisable; 1 = accurately drawn but poorly placed/incomplete but correctly placed; 2 = accurately drawn and correctly placed), yielding a maximum raw score of 36. Higher scores reflect better performance.

10. RCFT recall

    Time frame: Within 6 months of participants receiving their final diagnosis.

    Rey Complex Figure Test (RCFT) immediate recall was used to assess participants' memory by requiring them to reproduce a complex figure from memory after a short delay. Performance is evaluated based on the reproduction of 18 figure elements, each scored on a scale from 0 to 2 (0 = incorrectly placed/absent; 0.5 = inaccurately drawn/incorrectly placed but recognisable; 1 = accurately drawn but poorly placed/incomplete but correctly placed; 2 = accurately drawn and correctly placed), yielding a maximum raw score of 36. Higher scores reflect better performance.

11. Information

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Information subtest of the Wechsler Adult Intelligence Scale (WAIS) was used to assess participants' verbal comprehension. The subtest comprises 26 dichotomously scored questions (0 = incorrect; 1 = correct), with a maximum raw score of 26. Higher scores indicate better performance.

12. Similarities

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Similarities subtest of the Wechsler Adult Intelligence Scale (WAIS) was used to assess participants' verbal reasoning. Consisting of 18 pairs of words, for which participants are asked to describe how the items are similar, responses are scored on a 3-point scale (0 = incorrect; 1 = functional/concrete; 2 = abstract). Raw scores range from 0 to 36, with higher scores indicating better performance.

13. Block Design

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Block Design subtest of the Wechsler Adult Intelligence Scale (WAIS) assesses participants' visuospatial abilities. Performance is scored based on the accuracy and speed in reproducing geometric patterns. While the first few items are simple and scored on a 2-point scale (0 = inaccurate; 2 = accurate), later items become more complex and thus yield higher scores (ranging from 0 to 7 depending on the speed of completion). Total scores range from 0 to 66, where higher scores indicate better performance.

14. Digit Span

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Digit Span subtest of the Wechsler Adult Intelligence Scale (WAIS) was administered to assess participants' working memory and attention. Participants repeated digit sequences of increasing length, with each trial scored as correct or incorrect. The span length of digits to be recalled ranged from 2 to 9 for the forward and sequencing conditions and from 2 to 8 for the backward condition. Total scores range from 0 to 48, with higher scores indicating better performance.

15. Coding

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Coding subtest of the Wechsler Adult Intelligence Scale (WAIS) was used to assess processing speed. Within a 120-second time limit, participants are required to transcribe symbols paired with digits as quickly and accurately as possible. Performance is scored as the number of correctly completed symbols (0 = incorrect; 1 = correct), with higher scores indicating better performance.

16. Arithmetic

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Arithmetic subtest of the Wechsler Adult Intelligence Scale (WAIS) was administered to assess working memory and processing speed. Participants solved 22 orally presented arithmetic problems. Performance was scored as the number of correct answers, with one point awarded per correct item (minimum = 0; maximum = 22). Higher scores indicate better performance.

17. Matrix Reasoning

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Matrix Reasoning subtest of the Wechsler Adult Intelligence Scale (WAIS) was used to assess logical thinking. Comprising 26 items of increasing difficulty, participants identify patterns and select the correct missing piece from several response options. Responses are scored dichotomously (0 = incorrect; 1 = correct), yielding a total score ranging from 0 to 26. Higher scores indicate better performance.

18. TMT A

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Trail Making Test A (TMT-A) was administered to assess attention and processing speed. Performance is measured by the time required to sequentially connect numbered dots in ascending order, with longer completion times indicating worse performance.

19. TMT B

    Time frame: Within 6 months of participants receiving their final diagnosis.

    The Trail Making Test B (TMT-B) was administered to assess executive functioning. Performance is measured by the time required to connect numbered and lettered dots in an alternating ascending order, with longer completion times indicating worse performance.

20. Parkinsonism

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    Presence of parkinsonism was determined based on clinical interviews with participants. Responses were coded as present/absent/unknown for parkinsonism symptoms.

21. UPDRS-III

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    The Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) was administered to assess the presence and severity of parkinsonian motor symptoms. The scale comprises 33 items rated on a 5-point scale (0 = normal to 4 = severe), with higher scores indicating greater motor impairment (minimum = 0; maximum = 132).

22. Visual hallucinations

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    The presence of visual hallucinations was assessed based on clinical interviews. Responses were coded as either present/absent/unknown.

23. NPI

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    The Neuropsychiatric Inventory (NPI) was used to assess the presence of visual hallucinations. Responses were evaluated across three stages: presence, frequency, and severity. Presence of visual hallucinations was coded dichotomously as "Yes" or "No". Frequency was rated on a 4-point scale ranging from 1 (occasionally) to 4 (very frequently), whereas severity was rated on a 3-point scale ranging from 1 (mild) to 3 (severe). Domain scores were calculated by multiplying frequency and severity scores, resulting in a total score ranging from 0 to 12. Higher scores indicate greater impairment from visual hallucinations.

24. Cognitive fluctuations

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    Clinical interviews were used to assess the presence of cognitive fluctuations. Responses were coded as present/absent/unknown.

25. Mayo Fluctuations Scale

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    The Mayo Fluctuations Scale was administered to assess cognitive fluctuations. The scale comprises four dichotomous questions (0 = no; 1 = yes), with total scores ranging from 0 to 4. Higher scores thus indicate greater impairment.

26. REM Sleep Behaviour Disorder

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    Clinical interviews were used to assess the presence of REM Sleep Behaviour Disorder (RBD). Responses were coded as present/absent/unknown.

27. Mayo Sleep Questionnaire

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    The Mayo Sleep Questionnaire is a 16-item instrument used to assess the presence of REM Sleep Behaviour Disorder (RBD). Items are answered dichotomously (0 = no; 1 = yes). The likelihood of RBD is estimated by summing the "yes" responses to the four key RBD sub-questions, yielding a total score ranging from 0 (low likelihood of RBD) to 4 (high likelihood of RBD).

28. Polysomnography

    Time frame: From enrollment to the end of the diagnostic rounds (typically 3 months).

    Polysomnography was used to assess the presence of REM Sleep Behaviour Disorder (RBD) according to standard clinical assessment. Polysomnographic findings were coded as present/absent/unknown for the diagnosis of RBD.