TRIALS EXPLAINED

A clinical trial is a carefully designed research study that tests how well a medical intervention—such as a new drug, vaccine, medical device, treatment strategy, or behavioral intervention—works in people.

The main goal is to find out whether the intervention is safe, effective, and better than current standard treatments.

KEY STEPS IN A CLINICAL TRIAL

1: Preclinical Research

    • Before testing on humans, scientists study the intervention in labs and animals to gather safety and efficacy data.

2: Regulatory Approval

  • Researchers must get approval from regulatory authorities (like the FDA in the U.S. or EMA in Europe) and ethics committees to ensure patient safety.

3: Phases of Clinical Trials:

Phase 1

20-100 healthy volunteers

These trials test an experimental treatment on a small group of people for the first time. The purpose is:

1) Assess the treatment’s safety
2) Find out what a safe range would be for dosage
3) Identify side effects

Phase II

100-300 patients

The treatment is given to a larger group of people to:

1) Obtain preliminary data on the effectiveness of the treatment for a particular disease or condition
2) Further assess the treatment’s safety
3) Determine the best dose

Phase III

300-3000+ patients

The treatment is given to even larger groups of people to:

1) Confirm its effectiveness
2) Monitor side effects
3) Compare it to commonly used treatments
4) Collect information that will allow the treatment to be used safely on the market

Phase IV

Post market

Done after the treatment is approved and is on the market. Gather information on things, like the best way to use a treatment, and the long-term benefits and risks

 

4: Randomisation &
Control

    • Participants are often randomly assigned to different groups:
      • Experimental group: receives the new treatment
      • Control group: receives standard treatment or placebo
    • This helps avoid bias and ensures results are reliable.

5: Blinding

    • Single-blind: Participants don’t know which treatment they get.
    • Double-blind: Neither participants nor researchers know.
    • This minimizes placebo effects and observer bias.

6: Data Collection & Monitoring

    • Researchers collect data on outcomes, side effects, and other health measures.
    • An independent Data Monitoring Committee often oversees the trial for safety.

7: Analysis & Reporting

    • Data are analyzed statistically to determine whether the new intervention is effective.
    • Results are shared in scientific journals, regulatory reports, or with the public.
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phenoptype

Phenotype refers to an individual’s observable traits, such as height, eye color and blood type. A person’s phenotype is determined by both their genomic makeup (genotype) and environmental factors.

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oxidative seres

an imbalance between unstable molecules called “free radicals” and protective “antioxidants” in your body

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Metabolism & bioenergetics

describe how your body turns food into fuel and uses that energy to live. 

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Small Molecule

a tiny chemical compound, much smaller than big biological structures like proteins, that can easily travel inside our cells to act as medicine (like aspirin or ibuprofen), a building block (like glucose), or a signaling tool in the body, often taken as pills because they’re easy to absorb and distribute

 

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Nucleic acid

(DNA and RNA) are the essential information-carrying molecules in all life, acting like blueprints that store and transmit genetic instructions for building and operating cells, directing everything from growth to protein production, and passing traits from parents to offspring.

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SNP-single nucleotide polymorphisms

a single-letter spelling difference in a gene. SNPs, pronounced ‘snips’, are common and most don’t change the function of the gene.

 
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at risk

You do not know if you carry the genetic mutation for HD gene 

 
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TFC-total functional capacity

A standardized rating scale for function in HD, used to assess capacity to work, handle finances, perform domestic chores and self-care tasks.
Scores range from 0 to 13, with higher scores indicating better functional capacity. 

 
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Double-blinded

 means that neither the participant nor the clinical trial doctor can choose or know the group the participant is in until the trial is over. This approach helps to prevent bias.

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Open label

A trial in which the patient and doctor know what drug is being used. Open label trials are susceptible to bias through placebo effects.

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Gene therapy

a technique that aims to treat or prevent diseases by modifying a person’s genes. It involves introducing, removing, or changing genetic material (DNA or RNA) within a patient’s cells.

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UHDRS- Unified Huntington Disease Rating Scale

A standardized neurological examination that aims to provide a uniform assessment of the clinical features of HD

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CAG repeat

The stretch of DNA at the beginning of the HD gene, which contains the sequence CAG repeated many times, and is abnormally long in people who will develop HD

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Wild-type

the opposite of ‘mutant’. Wild-type huntingtin, for example, is the ‘normal’, ‘healthy’ protein

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Tolerabilty

How well a person can handle a treatment without having serious or uncomfortable side effects.

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Striatum

Part of the brain that  coordinates multiple aspects of cognition, including both motor and action planning, decision-making, motivation, reinforcement, and reward system.

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Randomized allocation

A type of allocation strategy in which participants are assigned to the arms of a clinical trial by chance.

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Radioligand

a radioactive substance that binds to a specific target in the body, allowing visualization of that target’s distribution and activity

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Protein

Protein builds, maintains, and replaces the tissues in your body. The building blocks of life.

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Premanifest / Prodromal

Prior to onset or diagnosis of movement symptoms.

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Placebo

A placebo is a dummy medicine containing no active ingredients. The placebo effect is a psychological effect that causes people to feel better even if they’re taking a pill that doesn’t work.

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PK - Pharmacokinetics

The movement of drugs through the body

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PD - Pharmacodynamics

The body’s biological response to drugs

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PET scan

Positron emission tomography which produces detailed 3-dimensional images of the inside of the body.

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Neuron

Brain cells that store and transmit information

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MRI

Magentic resonance imaging: A technique using powerful magnetic fields to produce detailed images and visualizes the structure of organs, tissues, and bones 

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mHTT

Mutant huntingtin protein. The protein produced by the faulty HD gene.

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Manifest

after HD diagnosis, or when symptoms are already showing

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Longitudinal study

A study where each participant is looked at several times over a time period – unlike a cross-sectional study, where each participant is looked at only once

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HTT

one abbreviation for the gene that causes Huntington’s disease. The same gene is also called HD and IT-15

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fMRI

functional MRI:As with MRI, a technique using powerful magnetic fields  but focusing on brain function by measuring and mapping changes in blood flow, revealing which areas of the brain are active during specific tasks or cognitive processes

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CSF - cerebrospinal fluid

A clear fluid produced by the brain, which surrounds and supports the brain and spinal cord.

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Efficacy

A measure of whether a treatment works or not

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ASO(Antisense oligonucleotides)

A type of gene silencing treatment in which specially designed DNA molecules are used to switch off a gene

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Biomarker

a test of any kind – including blood tests, thinking tests and brain scans – that can measure or predict the progression of a disease like HD. Biomarkers may make clinical trials of new drugs quicker and more reliable

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BDNF

Brain-derived neurotrophic factor: a growth factor that may be able to protect neurons in HD.

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Allele

one of the two copies of a gene

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Plasma

Liquid component of the blood.

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Gene

The basic unit of heredity passed from parent to child. Genes are made up of sequences of DNA and are arranged, one after another, at specific locations on chromosomes in the nucleus of cells.

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Phase

Clinical trial phases are different stages of research that assess the safety and effectiveness of a new medical treatment or intervention in humans.

Each phase has a specific goal and involves a different number of participants. Generally, there are 4 phases (I-IV), with Phase I focusing on safety and dosage, Phase II on efficacy and side effects, Phase III on comparing the new treatment with standard treatments, and Phase IV on long-term safety monitoring.