The Irritability Scale total score ranges from 0 to 42, with higher scores indicating greater irritability.

The Irritability Scale total score ranges from 0 to 42, with higher scores indicating greater irritability.

The HADS is a self-report, 14-item scale (7 items relate to anxiety and 7 relate to depression) used to determine the levels of anxiety and depression that a person is experiencing. The total score ranges from 0 to 42 (21 per subscale), with higher scores signifying worse symptoms.

The HADS is a self-report, 14-item scale (7 items relate to anxiety and 7 relate to depression) used to determine the levels of anxiety and depression that a person is experiencing. The total score ranges from 0 to 42 (21 per subscale), with higher scores signifying worse symptoms.

The NPI-Q is a 12-domain informant-based interview that assesses neuropsychiatric symptoms over the previous month.The total NPI-Q severity score ranges from 0 to 36, with higher scores indicate greater symptoms severity.

The NPI-Q is a 12-domain informant-based interview that assesses neuropsychiatric symptoms over the previous month.The total NPI-Q severity score ranges from 0 to 36, with higher scores indicate greater symptoms severity.

Caregiver distress associated with the symptom is rated on an anchored 0- to 5-point scale, which total sum ranges from 0 to 60. Higher scores indicate greater caregiver distress related to patient's neuropsychiatric symptoms.

Caregiver distress associated with the symptom is rated on an anchored 0- to 5-point scale, which total sum ranges from 0 to 60. Higher scores indicate greater caregiver distress related to patient's neuropsychiatric symptoms.

Data were not collected for 1 participant in the Dextromethorphan/quinidine 20mg/10mg (DM/Q 20mg/10mg) arm. Data were not collected for 1 participant in the Placebo arm

The PBA-s is a semistructured interview to measure severity and frequency of behavioral problems in Huntington's disease. The PBA-s is an 11-item scale rating the frequency and severity of symptoms. The total score for irritability/aggression subscale ranges from 0 to 32, with higher scores indicating greater behavioral symptoms severity.

The PBA-s is a semistructured interview to measure severity and frequency of behavioral problems in Huntington's disease. The PBA-s is an 11-item scale rating the frequency and severity of symptoms. The total score for irritability/aggression subscale ranges from 0 to 32, with higher scores indicating greater behavioral symptoms severity.

The TMS comprises the motor section of the UHDRS, a 31-item subscale that comprehensively evaluates motor aspects of HD. The overall 31 items are each rated from grade 0 (not affected) to grade 4 (most severely affected), resulting in a range of 0-124 points.

The TMS comprises the motor section of the UHDRS, a 31-item subscale that comprehensively evaluates motor aspects of HD. The overall 31 items are each rated from grade 0 (not affected) to grade 4 (most severely affected), resulting in a range of 0-124 points.

The TMC comprises 7 of the 31 items in the TMS, which are related to chorea symptoms. The total TMC score ranges from 0 to 28, with higher scores indicating greater chorea severity.

The TMC comprises 7 of the 31 items in the TMS, which are related to chorea symptoms. The total TMC score ranges from 0 to 28, with higher scores indicating greater chorea severity.

The TFC lists five stages of Huntington's Disease and five levels of function in the domains of workplace, finances, domestic chores, activities of daily living and requirements for unskilled or skilled care. The total TFC score ranges from 0 to 13, with higher scores signifying better functioning.

The TFC lists five stages of Huntington's Disease and five levels of function in the domains of workplace, finances, domestic chores, activities of daily living and requirements for unskilled or skilled care. The total TFC score ranges from 0 to 13, with higher scores signifying better functioning.

The C-SSRS is a suicidal ideation and behavior rating scale with yes/no responses. The first part (Items 1-5) rates an individual's degree of suicidal ideation on a 0-5 scale, ranging from "wish to be dead" to "active suicidal ideation with specific plan and intent and behaviors". The C-SSRS outcomes are categories and have binary responses (yes/no). Suicidal ideation is considered when the patient responds a "yes" answer at any time during treatment to any one of the five suicidal ideation questions (Categories 1-5) on the C-SSRS. The sum of the 5 intensity item scores create a total score (range 0 to 25) to represent the intensity rating (higher scores indicate more severe suicidal ideation).

The C-SSRS is a suicidal ideation and behavior rating scale with yes/no responses. The first part (Items 1-5) rates an individual's degree of suicidal ideation on a 0-5 scale, ranging from "wish to be dead" to "active suicidal ideation with specific plan and intent and behaviors". The C-SSRS outcomes are categories and have binary responses (yes/no). Suicidal ideation is considered when the patient responds a "yes" answer at any time during treatment to any one of the five suicidal ideation questions (Categories 1-5) on the C-SSRS. The sum of the 5 intensity item scores create a total score (range 0 to 25) to represent the intensity rating (higher scores indicate more severe suicidal ideation).

The questions 6-10 of the C-SSRS are related to suicidal behavior, and the outcome is a simple yes/no response. Suicidal behavior occurs if the patient answers a "yes" at any time during treatment to any one of the five suicidal behavior questions (Categories 6-10) on the C-SSRS.

The questions 6-10 of the C-SSRS are related to suicidal behavior, and the outcome is a simple yes/no response. Suicidal behavior occurs if the patient answers a "yes" at any time during treatment to any one of the five suicidal behavior questions (Categories 6-10) on the C-SSRS.

The MoCA is a rapid screening instrument for mild cognitive dysfunction. It assesses different cognitive domains with a total possible score of 0 to 30 points; a score of 26 or above is considered normal for the general population.

The MoCA is a rapid screening instrument for mild cognitive dysfunction. It assesses different cognitive domains with a total possible score of 0 to 30 points; a score of 26 or above is considered normal for the general population.

The CGI is a stand-alone assessment of the clinician's view of the patient's global functioning prior to and after initiating a study medication.

The CGI is a stand-alone assessment of the clinician's view of the patient's global functioning prior to and after initiating a study medication. The CGI is a 3-item observer-rated scale that measures illness severity (CGI-S), global improvement or change (CGI-I) and therapeutic response. The scale ranges from 1-7, with higher scores indicating worse outcomes.

The CGI is a stand-alone assessment of the clinician's view of the patient's global functioning prior to and after initiating a study medication.

The UHDRS - cognitive function assessment a phonetic verbal fluency test, the Symbol Digit Modalities Test, and the Stroop Interference Test. These tests do not have a predefined score range, but higher scores indicate better cognitive performance.

Data were not collected for this outcome measure

The UHDRS - cognitive function assessment a phonetic verbal fluency test, the Symbol Digit Modalities Test, and the Stroop Interference Test. These tests do not have a predefined score range, but higher scores indicate better cognitive performance.

Data were not collected for this outcome measure