A Study to Evaluate SAGE-217 in Participants With Essential Tremor

Part A: Change From Baseline in Kinesia Upper Limb Individual Item Score at Day 7

The accelerometer-based Kinesia upper limb total score is the sum of Kinesia kinetic tremor scores across both sides of the body. The individual items included forward outstretched postural tremor (FOPT), lateral "wing beating" postural tremor (LWBPT), and kinetic tremor (KT) scores from both sides of the body. Each upper limb individual item question score for each side of the body ranges from 0 to 4, with higher scores indicating more tremors/greater tremor amplitude. The Kinesia upper limb total score ranges from 0 to 24, with higher scores indicating more tremors/greater tremor amplitude. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 7 (8 hours [hr] postdose [pd])

Part A: Change From Baseline in the Tremor Research Group (TRG) Essential Tremor Rating Assessment Scale (TETRAS) Upper Limb Total Score at Day 7

The TETRAS performance subscale upper limb total score is the sum of the TETRAS individual item scores from both sides of the body. The TETRAS individual item score included TETRAS Performance Subscale item 4a, 4b and 4c scores \[4a: forward outstretched postural tremor (FOPT) and 4b: lateral "wing beating" postural tremor (LWBPT) scores and 4c: Kinetic tremor (KT) score\] from both sides of the body. Each individual item score ranges from 0 to 4; The total upper limb score ranges from 0 to 24, higher scores indicate more severe tremor. A negative change indicates improvement.

Time frame: Baseline (Day 1) and Day 7 (8 hours postdose)

Change From Baseline in the TETRAS Upper Limb Individual Items (Performance Subscale Items 4a, 4b, or 4c) Scores at Day 7

The TETRAS individual item score is the sum of the TETRAS Performance Subscale items 4a, 4b, or 4c scores \[4a: forward outstretched postural tremor (FOPT), 4b: lateral "wing beating" postural tremor (LWBPT), 4c: kinetic tremor\] from both sides of the body. Each TETRAS score ranges from 0 to 4; the total score ranges from 0 to 16; higher scores indicate more severe tremor. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 7 (8 hours postdose)

Part A: Change From Baseline in TETRAS Performance Subscale Score (Items 6, 7, and 8) at Day 7

The TETRAS Performance Subscale score includes 9 items. Out of these 9 items, Item 6 is Archimedes spirals (AS), Item 7 is Handwriting, and Item 8 is Dot approximation task (DAT). Each item was scored from 0 to 4, for both sides of the body, each item has a total score of 0 to 8, where higher scores indicate more severe tremor. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 7 (predose)

Part B: Change From Randomization in the Kinesia Upper Limb Total Score at Day 14

The accelerometer-based Kinesia upper limb total score is the sum of Kinesia kinetic tremor scores across both sides of the body. The individual items included forward outstretched postural tremor (FOPT), lateral "wing beating" postural tremor (LWBPT), and kinetic tremor (KT) scores from both sides of the body. Each upper limb individual item question score for each side of the body ranges from 0 to 4. The Kinesia upper limb total score ranges from 0 to 24, with higher scores indicating more tremors/greater tremor amplitude. A negative change from Randomization indicates improvement.

Time frame: Randomization (Day 8, predose) and Day 14 (predose)

Part B: Change From Randomization in the Kinesia Upper Limb Individual Item Score at Day 14

The accelerometer-based Kinesia upper limb total score is the sum of Kinesia kinetic tremor scores across both sides of the body. The individual items included forward outstretched postural tremor (FOPT), lateral "wing beating" postural tremor (LWBPT), and kinetic tremor (KT) scores from both sides of the body. Each upper limb individual item question score for each side of the body ranges from 0 to 4. The Kinesia upper limb total score ranges from 0 to 24, with higher scores indicating more tremors/greater tremor amplitude. A negative change from Randomization indicates improvement.

Time frame: Randomization (Day 8, predose) and Day 14 (predose)

Part B: Change From Randomization in the TETRAS Upper Limb Total Score at Day 14

The TETRAS performance subscale upper limb total score is the sum of the TETRAS individual item scores from both sides of the body. The TETRAS individual item score included TETRAS Performance Subscale item 4a, 4b and 4c scores \[4a: forward outstretched postural tremor (FOPT) and 4b: lateral "wing beating" postural tremor (LWBPT) scores and 4c: Kinetic tremor (KT) score\] from both sides of the body. Each individual item score ranges from 0 to 4; The total upper limb score ranges from 0 to 24, higher scores indicate more severe tremor. A negative change from Randomization indicates improvement.

Time frame: Randomization (Day 8, predose) and Day 14 (predose)

Part B: Change From Randomization in the TETRAS Upper Limb Individual Item (Performance Subscale Items 4a and 4b) Score at Day 14

The TETRAS individual item score is the sum of the TETRAS Performance Subscale item 4a and 4b scores \[4a: forward outstretched postural tremor (FOPT) and 4b: lateral "wing beating" postural tremor (LWBPT) scores\] from both sides of the body. Each TETRAS score ranges from 0 to 4; the total score ranges from 0 to 16, higher scores indicate more severe tremor. A negative change from Randomization indicates improvement.

Time frame: Randomization (Day 8, predose) and Day 14 (predose)

Part B: Change From Randomization in the TETRAS Performance Subscale Item 4c (Kinetic Tremor) Combined Score at Day 14

The TETRAS kinetic tremor combined score is the sum of the TETRAS Performance Subscale item 4c (kinetic tremor) scores from both sides of the body. The TETRAS kinetic tremor score ranges from 0 to 4, the total score for both sides of the body ranges from 0 to 8, higher scores indicate more severe tremor. A negative change from Randomization indicates improvement.

Time frame: Randomization (Day 8, predose) and Day 14 (predose)

Part B: Change From Baseline in TETRAS Performance Subscale (Items 6, 7, and 8) Score at Day 14

The TETRAS Performance Subscale score includes 9 items. Out of these 9 items, Item 6 is Archimedes spirals (AS), Item 7 is Handwriting, and Item 8 is Dot approximation task (DAT). Each item was scored from 0 to 4, for both sides of the body, each item has a total score of 0 to 8, where higher scores indicate more severe tremor. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 14 (predose)

Part C: Change From Baseline in the Kinesia Upper Limb Individual Item Score at Day 15

The accelerometer-based Kinesia upper limb total score is the sum of Kinesia kinetic tremor scores across both sides of the body. The individual items included forward outstretched postural tremor (FOPT), lateral "wing beating" postural tremor (LWBPT), and kinetic tremor (KT) scores from both sides of the body. Each upper limb individual item question score for each side of the body ranges from 0 to 4. The Kinesia upper limb total score ranges from 0 to 24, with higher scores indicating more tremors/greater tremor amplitude. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 15

Part C: Change From Baseline in the TETRAS Upper Limb Total Score at Day 15

The TETRAS performance subscale upper limb total score is the sum of the TETRAS individual item scores from both sides of the body. Each individual item score ranges from 0 to 4; The total upper limb score ranges from 0 to 24, higher scores indicate more severe tremor. A negative change indicates improvement.

Time frame: Baseline (Day 1) and Day 15

Part C: Change From Baseline in the TETRAS Upper Limb Individual Item (Performance Subscale Items 4a and 4b) Score at Day 15

The TETRAS individual item score is the sum of the TETRAS Performance Subscale item 4a and 4b scores \[4a: forward outstretched postural tremor (FOPT) and 4b: lateral "wing beating" postural tremor (LWBPT) scores\] from both sides of the body. Each TETRAS score ranges from 0 to 4; the total score ranges from 0 to 16, higher scores indicate more severe tremor. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 15

Part C: Change From Baseline in TETRAS Performance Subscale (Items 6, 7, and 8) Scores at Day 15

The TETRAS Performance Subscale score includes 9 items. Out of these 9 items, Item 6 is Archimedes spirals (AS), Item 7 is Handwriting, and Item 8 is Dot approximation task (DAT). Each item was scored from 0 to 4, for both sides of the body, each item has a total score of 0 to 8, where higher scores indicate more severe tremor. A negative change from Baseline indicates improvement.

Time frame: Baseline (Day 1) and Day 15

Parts A, B and C: Number of Participants With at Least One Treatment-Emergent Adverse Event (TEAE) or Serious Adverse Event (SAE)

An Adverse Event (AE) was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug-related. Adverse events that occurred after the first administration of study drug were denoted as TEAEs. A Serious Adverse Event (SAE) was an AE occurring during any study phase and at any dose of the study drug, comparator, or placebo, that fulfilled the following outcomes: death, a life-threatening adverse event, inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant incapacity or substantial disruption of the ability to conduct normal functions, or a congenital anomaly/birth defect. Important medical events that may not result in death, be life-threatening, or require hospitalization may be considered serious when, based upon appropriate medical judgment, they may jeopardize the participant and may require medical or surgical intervention to prevent one of the outcomes listed in this definition.

Time frame: From first dose of study drug through 14 days after the last dose (Up to 28 days)

Part A, B and C: Number of Participants With Suicidal Ideation as Assessed by the Columbia-Suicide Severity Rating Scale (C-SSRS) Score

The C-SSRS consists of a baseline and post-baseline (PB) evaluation that assesses the lifetime experience of the participants with suicidal ideation and behavior. The data for suicidal ideation were summarized for participants who answered 'Yes'. Suicide ideation was categorized as 1) wish to be dead and 2) non-specific active suicidal thoughts.

Time frame: Baseline and post-baseline (up to 28 days)

Number of Participants With Clinically Significant Vital Signs

Vital signs included heart rate, respiratory rate, temperature, and blood pressure.

Time frame: Up to 28 days

Number of Participants With Clinically Significant Laboratory Parameters

Laboratory parameters included hematology, blood chemistry, and urinalysis.

Time frame: Up to 28 days

Number of Participants With Clinically Significant Electrocardiogram (ECG) Values

A 12-lead ECG was performed.

Time frame: Up to 28 days

Parts A and B: Change From Baseline in Stanford Sleepiness Scale (SSS)

The SSS was designed to quickly assess how alert a subject is feeling. Degrees of sleepiness and alertness are rated on a scale of 1 to 7, where the lowest score of 1 indicates the subject is "feeling active, vital, alert, or wide awake" and the highest score of 7 indicates the participant is "no longer fighting sleep, sleep onset soon; having dream-like thoughts". Greater changes from baseline indicate greater sedation. A positive change from baseline indicates improvement.

Time frame: Baseline (Day 1), Day 7 (predose) for Part A, Day 14 (predose) for Part B

Parts A, B and C: Change From Baseline in Bond-Lader Visual Analogue Scale (VAS) Score

Mood was assessed using the Bond-Lader VAS score. This is a 16-part self-administered questionnaire that employs a 100-mm VAS to explore different aspects of self-reported mood. Three factor scores for (alertness, contentedness, and calmness) were calculated using following equations based on normalized VAS scores: * Alertness = 0.827X1 + 0.618X3 + 0.755X4 + 0.642X5 + 0.776X6 + 0.635X9 + 0.792X11 + 0.593X12 + 0.614X15; * Contentedness = 0.677X7 + 0.697X8 + 0.823X13 + 0.738X14 + 0.594X16; and * Calmness = 0.845X2 + 0.677X10, where Xi represents a subject's item score after normalization, and i represents the item number from the entire scale (in order from 1-16). A negative change from baseline (CFB) indicated more alertness, more contentedness, and more calmness.

Time frame: Baseline (Day 1), Day 7 (predose) for Part A, Day 14 (predose) for Part B and Day 15 for Part C

Parts A, B and C: Participant's Feeling After Taking the Study Drug as Assessed by Drug Effects Questionnaire (DEQ-5) Score

Participants responded to 5 DEQs based on how they are feeling after taking the study drug. DEQ-5 were as follows; Q1: Do you FEEL a drug effect right now? Q2: Are you HIGH right now? Q3: Do you DISLIKE any of the effects that you are feeling right now? Q4: Do you LIKE any of the effects that you are feeling right now? Q5: Would you like MORE of the drug you took, right now? The answers were recorded on a 100-mm VAS, with the answer for each being "Not at all" (0 mm) and "Extremely" (100 mm) at the extremes. There were options to record "Not applicable" for questions 3 and 4 if no drug effects were felt and for question 5 prior to administration of study medication, and these participants were excluded from the data summarization. Higher score on Q1 indicates a drug effect; on Q2 indicates feeling high; on Q3 indicates disliking the drug; and on Q4 and Q5 indicates liking the drug.

Time frame: Baseline (Day 1), Day 7 (2 hours postdose) for Part A, Day 14 (2 hours postdose) for Part B and Day 15 for Part C