No treatment currently slows or reverses the neurodegenerative process in Huntington’s disease (HD), but a range of approved medications can meaningfully manage its symptoms, and an unusually active pipeline of experimental therapies aims to change the disease’s course. The landscape spans drugs already in use for involuntary movements and psychiatric symptoms, investigational gene-silencing and gene-editing strategies, and supportive therapies like structured exercise and deep brain stimulation. For someone living with HD or caring for someone who is, understanding what is available now and what is coming matters for making informed decisions at every stage of the disease.
Managing Chorea with VMAT2 Inhibitors
The most visible motor symptom of HD is chorea, the involuntary, flowing movements that can affect the face, limbs, and trunk. The primary pharmacological approach targets a protein called VMAT2, which packages dopamine for release in the brain. By dialing down excess dopamine signaling, VMAT2 inhibitors reduce the severity of these movements. Three drugs in this class have been studied: tetrabenazine (approved in 2008), deutetrabenazine (approved in 2017), and valbenazine. A systematic review and meta-analysis found that VMAT2 inhibitors significantly reduced chorea scores compared with placebo, with consistent results across trials and no meaningful statistical inconsistency between studies.1PubMed Central. Efficacy and Safety of VMAT-2 Inhibitors and Dopamine Stabilizers for Huntington’s Chorea: A Systematic Review, Meta-Analysis, and Trial Sequential Analysis A separate systematic review confirmed that all three VMAT2 inhibitors significantly lowered chorea scores, with both clinician-rated and patient-reported improvement scales favoring active treatment over placebo.2PubMed. Safety and efficacy of VMAT2 inhibitors in Huntington Disease: A systematic review
These drugs help, but they come with trade-offs. Tetrabenazine can worsen depression and cause sedation, which is a real concern in a population where depression is already common. Deutetrabenazine was engineered to have a longer half-life and smoother pharmacokinetics, which tends to mean fewer peaks and troughs in side effects. Valbenazine, originally approved for tardive dyskinesia, is being studied more recently in HD. None of these drugs address the underlying neurodegeneration. They manage a symptom, and for many patients that is still a meaningful improvement in daily function and dignity.
Treating the Psychiatric and Behavioral Symptoms
HD is not just a movement disorder. Depression, irritability, anxiety, apathy, and sometimes psychosis are central features that often cause more distress to patients and families than the motor symptoms. The evidence base for treating these symptoms in HD specifically is thinner than you might expect, relying heavily on clinical experience borrowed from other conditions rather than large HD-specific trials. A systematic review of pharmacological treatment for neuropsychiatric symptoms in HD found that one randomized controlled trial reported improvement in overall neuropsychiatric symptoms with nabilone (a synthetic cannabinoid), while another found that fluoxetine slightly improved irritability. Lower-level evidence from open studies suggests that atypical antipsychotics like olanzapine and cariprazine may help with depression, aggression, anxiety, and obsessive thoughts.3PubMed Central. Pharmacological Treatment of Neuropsychiatric Symptoms in Huntington’s Disease: A Systematic Review
In practice, clinicians use algorithms guided by expert consensus rather than by HD-specific randomized trials. An international survey of HD experts found that when irritability co-occurs with depression or anxiety, SSRIs are the first choice. When it co-occurs with psychosis, aggression, or impulsivity, antipsychotics are preferred. For irritability paired with insomnia, benzodiazepines or mirtazapine are favored.4PubMed Central. Huntington Disease An International Survey-based Algorithm for the Pharmacologic Treatment of Irritability in Huntington’s Disease Separate expert-based consensus guidelines for symptoms like agitation, anxiety, apathy, psychosis, and sleep disorders note that while most of these symptoms have not been specifically tested in HD populations, clinical experience shows they are treatable using strategies developed for other conditions.5PubMed Central. Clinical Management of Neuropsychiatric Symptoms of Huntington Disease: Expert-Based Consensus Guidelines on Agitation, Anxiety, Apathy, Psychosis and Sleep Disorders The honest picture is that psychiatrists treating HD are working with a patchwork of borrowed knowledge, clinical intuition, and a handful of small studies. It usually works reasonably well, but the field recognizes it needs better evidence.
The Push to Lower Huntingtin Protein
The defining genetic cause of HD is an expanded CAG repeat in the huntingtin gene, which produces a toxic form of the huntingtin protein. That protein accumulates in neurons, particularly in the striatum, and drives the progressive cell death that causes symptoms. The most direct disease-modifying strategy is to reduce the amount of this toxic protein being made. Several approaches aim to do this, and they represent the most watched area of HD research.
Antisense oligonucleotides (ASOs) are short synthetic stretches of modified DNA that bind to the messenger RNA produced by the huntingtin gene and mark it for destruction, preventing the protein from being made. The most advanced ASO program, tominersen, showed biological activity in early trials. An EEG-based study of patients treated with tominersen found increased resting-state brain activity in the theta/alpha frequency range compared with placebo, with a median increase of about 14% in that frequency band, suggesting the drug was having a measurable effect on brain function.6PubMed Central. Changes in brain activity with tominersen in early-manifest Huntington’s disease – Section: Tominersen treatment changes EEG activity in patients with Huntington’s disease However, the larger Phase 3 trial of tominersen was halted in 2021 after an independent monitoring board found that higher-dose patients were faring worse than those on placebo. The program has since been restructured with lower doses and less frequent administration. This setback was a major blow to the community, but it did not kill the concept of huntingtin lowering. It made the field more careful about dose, frequency, and which patients might benefit most.
A key safety consideration for any huntingtin-lowering approach is that normal huntingtin protein has important functions. Deleting the huntingtin gene before neural development is lethal in mice, and deleting it in the early postnatal period leads to progressive neurological problems. However, deleting it in adult mice that developed normally produces no neurological issues, suggesting that partial reduction of huntingtin in adults may be safe. The challenge is striking a balance between lowering toxic mutant huntingtin and preserving enough normal huntingtin for the cell’s needs, especially for non-selective approaches that reduce both forms equally.7Neuron. Huntingtin Lowering Strategies for Disease Modification in Huntington’s Disease
Targeting Somatic Repeat Expansion
One of the most exciting shifts in HD research over the past few years involves a process called somatic repeat expansion. The CAG repeat that causes HD is not static after birth. In certain tissues, particularly neurons in the striatum, the repeat continues to grow over a person’s lifetime. Longer repeats mean more toxic protein, and genetic studies have shown that the rate of this ongoing expansion is a major determinant of when symptoms begin. Targeting the machinery that drives this expansion is now a leading therapeutic strategy.
A key player is a DNA mismatch repair protein called MSH3. In mouse models, completely removing MSH3 prevented somatic expansion throughout the brain and body, and reducing MSH3 by half slowed the rate of expansion.8Brain. A CAG repeat threshold for therapeutics targeting somatic instability in Huntington’s disease Moving from mouse genetics to potential drugs, researchers have shown that antisense oligonucleotides designed to reduce MSH3 levels led to a dose-dependent stalling of CAG repeat expansion in human striatal neurons derived from HD patient cells.9PubMed. Antisense oligonucleotide-mediated MSH3 suppression reduces somatic CAG repeat expansion in Huntington’s disease iPSC-derived striatal neurons This approach is conceptually different from huntingtin lowering: instead of cleaning up toxic protein after it is made, it aims to prevent the mutation from getting worse in the first place. Several companies now have MSH3-targeting programs in or approaching clinical trials.
Small Molecules That Alter Huntingtin Production
Not all huntingtin-lowering strategies require injections into the spinal canal. One approach uses small molecules that can be taken orally and cross the blood-brain barrier. Branaplam, originally developed for spinal muscular atrophy, was found to modify the way huntingtin messenger RNA is processed. In cell-based experiments, branaplam promoted the inclusion of a normally skipped segment of the huntingtin gene that carries stop signals, causing the cell to destroy the altered transcript. This led to dose-dependent reductions in huntingtin protein, reaching up to about 55% reduction of normal huntingtin protein in one cell line.10Nature Communications. An orally available, brain penetrant, small molecule lowers huntingtin levels by enhancing pseudoexon inclusion An oral pill that lowers huntingtin would be transformative compared with repeated lumbar punctures for ASO delivery. However, the branaplam program in HD was discontinued after safety signals in clinical development, and other companies are pursuing related splicing-modulator approaches.
Gene Editing and Gene Therapy
CRISPR-based gene editing offers the theoretical possibility of a one-time treatment that permanently silences the mutant huntingtin gene. Researchers have demonstrated allele-specific editing in HD patient cells, meaning they can design guide RNAs that distinguish the mutant copy of the gene from the normal one based on small genetic variations. In one study, the CRISPR system excised a portion of huntingtin only from the allele carrying the mutation, leaving the normal copy intact.11PubMed Central. CRISPR/Cas9 Editing of the Mutant Huntingtin Allele In Vitro and In Vivo Further refinements have used pairs of guide RNAs that selectively delete a segment of the mutant gene, preventing production of both mutant huntingtin mRNA and protein.12Molecular Therapy – Methods & Clinical Development. PAM-altering SNP-based allele-specific CRISPR-Cas9 therapeutic strategies for Huntington’s disease
The delivery challenge for gene editing in HD is formidable. The affected neurons sit deep in the brain, and getting editing machinery into enough of them to make a clinical difference remains an unsolved problem. Adeno-associated virus (AAV) vectors are the most commonly studied delivery vehicle for gene therapies targeting the central nervous system, though the potential of AAVs specifically for HD treatment remains underexplored compared with other neurodegenerative conditions.13PubMed Central. Revolutionizing Huntington’s Disease Treatment: Breakthroughs in AAV-Mediated Gene Therapy Another experimental delivery method is focused ultrasound, which temporarily opens the blood-brain barrier in targeted areas. In preclinical work, combining focused ultrasound with small interfering RNA targeting huntingtin achieved about a 32% decrease in huntingtin expression in the striatum, with the reduction being dose-dependent and greater when the blood-brain barrier was disrupted more extensively.14SpringerOpen. Breaking Barriers in Huntington’s Disease Therapy: Focused Ultrasound for Targeted Drug Delivery
Neuroprotection Through the Sigma-1 Receptor
Pridopidine is a drug that has taken an unusual path through HD research. Initially studied as a dopamine stabilizer for motor symptoms, its mechanism of interest shifted when researchers realized its primary action at clinically relevant doses is through the sigma-1 receptor, a protein involved in cellular stress responses and mitochondrial health. In HD mouse models treated at an early, pre-symptomatic age, pridopidine significantly improved motor coordination, suggesting a delay in symptom onset, and the effect was tied to improved mitochondrial function mediated by the sigma-1 receptor.15Neurotherapeutics. The Sigma-1 Receptor Mediates Pridopidine Rescue of Mitochondrial Function in Huntington Disease Models In cell culture studies, pridopidine protected neurons expressing mutant huntingtin, and this protection was blocked when the sigma-1 receptor was knocked out, confirming the receptor as the drug’s key target.16PubMed Central. Pridopidine protects neurons from mutant-huntingtin toxicity via the sigma-1 receptor Pridopidine is now in late-stage clinical trials, and the hope is that it could offer neuroprotection rather than just symptom relief. Results have been mixed so far, and the field is watching closely.
Why Treating Early Might Matter Most
A recurring theme across HD research is that earlier intervention appears to work better. In mouse models, silencing the huntingtin gene at the pre-symptomatic stage prevented the striatal atrophy and motor deficits that untreated animals developed by six months, and it also slowed progression when animals already had some pathology.17Brain. Huntingtin silencing delays onset and slows progression of Huntington’s disease: a biomarker study This is consistent with what we know about neurodegeneration in general: once neurons are dead, no drug brings them back. The implication for people carrying the HD gene expansion is that future disease-modifying treatments may be most effective if started before symptoms are obvious.
This raises a practical question about how to measure whether a treatment is working in someone who does not yet have symptoms. Biomarkers are critical here. Neurofilament light chain (NfL), a protein released when neurons are damaged, has emerged as a leading candidate. In HD mouse models, NfL levels in blood and cerebrospinal fluid responded to the degree of mutant huntingtin lowering in the brain and to how early the intervention began, suggesting it could serve as a real-time readout of treatment effect.18PubMed Central. Elevated plasma and CSF neurofilament light chain concentrations are stabilized in response to mutant huntingtin lowering in the brains of Huntington’s disease mice A longitudinal study comparing NfL and mutant huntingtin levels as biomarkers found that NfL was a stronger monitoring and prognostic biomarker overall, though mutant huntingtin levels themselves still had prognostic value and could be useful as a pharmacodynamic marker in lowering trials.19PubMed Central. Mutant huntingtin and neurofilament light have distinct longitudinal dynamics in Huntington’s disease
Exercise, Rehabilitation, and Non-Drug Approaches
Amid the focus on molecular therapies, structured exercise and physical therapy are among the best-supported interventions currently available for HD. A mixed-methods systematic review found that several studies demonstrated improvement or maintenance of motor function over nine months or longer, a notable finding in a condition defined by progressive decline. Beyond physical gains like better walking, balance, and motor control with fewer falls, participants and caregivers reported benefits in confidence, independence, mood, and social engagement.20PubMed Central. Physical Therapy and Exercise Interventions in Huntington’s Disease: A Mixed Methods Systematic Review Clinical practice guidelines now recommend aerobic exercise, alone or combined with resistance training, and supervised gait training as Grade A interventions for people with HD, meaning the evidence supporting them is strong.21PubMed Central. Clinical recommendations to guide physical therapy practice for Huntington disease
Deep brain stimulation (DBS) is a surgical option for chorea that does not respond adequately to medication. A literature review covering 42 patients who received DBS targeting the globus pallidus internus found improvements in total motor scores and chorea subscores across most studies, with chorea reductions ranging from roughly 21% to 74%.22PubMed. Deep brain stimulation in Huntington’s disease: a literature review The wide range reflects how variable outcomes can be, and DBS is reserved for carefully selected patients. It is not a standard recommendation for most people with HD, but it represents an option when chorea is severe and medication alone is not enough.
Neuroinflammation as a Separate Target
Most disease-modifying strategies in HD focus on the huntingtin protein itself, either lowering it or preventing the gene from expanding further. But a parallel line of research focuses on neuroinflammation, the chronic activation of the brain’s immune cells (microglia) that accompanies and accelerates neuronal death in HD. Microglial activation and neuroinflammation drive progressive striatal neurodegeneration through mechanisms that are at least partially independent of the huntingtin protein itself, offering distinct therapeutic targets.23PubMed Central. Neuroinflammation as a therapeutic target in Huntington’s disease The appeal of this approach is that it could potentially be combined with huntingtin-lowering strategies for a two-pronged attack. Anti-inflammatory agents being explored range from repurposed drugs to novel compounds designed specifically for neuroinflammation, though none has yet reached late-stage clinical trials for HD.
Stem Cell Therapy
Replacing the neurons lost in HD with transplanted cells is an idea that has been around for decades, starting with fetal tissue grafts in the 1990s. The current focus has shifted to neural stem cells, which can be derived from various sources including patient-derived induced pluripotent stem cells. Preclinical trials in HD animal models have shown promise in improving cognitive and motor functions. However, stem cell therapy for HD remains in early stages and faces significant challenges including immune rejection, the need for immunosuppression, ethical considerations around certain cell sources, and technical hurdles in getting transplanted cells to integrate properly into the existing neural circuits.24PubMed Central. Advances in Stem Cell Therapy for Huntington’s Disease: A Comprehensive Literature Review For now, this approach is years from clinical availability, but it represents a conceptually distinct strategy from all the others: rebuilding what has been lost rather than slowing what is being lost.
Care in Advanced Stages
As HD progresses, the focus of care shifts. In advanced disease, swallowing difficulty becomes a major concern. A cross-sectional study of HD hospital admissions in the United States found that about 5% included gastrostomy tube placement, most commonly associated with aspiration pneumonia, dementia, malnutrition, and swallowing problems.25PubMed Central. Palliative care in advanced Huntington’s disease: a scoping review The decision about feeding tube placement is one of many end-of-life questions that ideally should be discussed well before the advanced stage, when the person with HD can still participate meaningfully in planning.
Advance directive completion in HD is not as common as you might expect given that the disease is predictable years in advance. In one U.S. study, about 38% of HD participants had an advance directive, and having close relatives with HD was significantly associated with having documented end-of-life wishes.26PubMed Central. Palliative care in advanced Huntington’s disease: a scoping review Palliative care specialists increasingly recognize that HD requires a different model than cancer-focused palliative care, since the trajectory of decline is much longer and the cognitive changes complicate communication and decision-making as the disease advances. Early referral to palliative care teams familiar with HD, ideally integrated with ongoing neurological management, can help families navigate the years of decisions that lie ahead.