Blurred Lines: When Similar Symptoms Can Mean Different Things

Huntington’s disease (HD) can be unpredictable. No two people experience the same journey, and symptoms can change over time. This can make it difficult to know when a new symptom is due to Huntington’s, or when it might be something different.

A new review by Dr Sahil Munjal and his team in Winston-Salem, North Carolina, explores catatonia, an uncommon condition that can occur alongside HD, but has received little research attention. By bringing together every published case of catatonia in people with HD, the researchers set out to understand why the condition can be difficult to recognise and why greater awareness could help to ensure people with HD receive the most appropriate care.

What Is Catatonia?

Catatonia is a complex condition that affects movement, behaviour, speech and thinking. It can vary widely from person to person and can arise alongside a range of different conditions. For example, it can occur in people with major depressive disorder or schizophrenia, as well as those with epilepsy or a traumatic brain injury. It is important to note that catatonia can improve and, with appropriate treatment, may eventually go away, particularly when the underlying cause is identified and treated.

Someone experiencing stuporous catatonia may become unusually quiet, motionless or unresponsive. Others develop excited catatonia, which can involve restlessness, agitation and impulsive behaviour. People experiencing catatonia may also repeat another person’s words (echolalia) or movements (echopraxia) or show unusual movements or facial expressions. This variability can make catatonia difficult to recognise, particularly when some of its features overlap with symptoms of other conditions.

This overlap is particularly relevant for people with HD as they may experience very different combinations and presentations of symptoms from person to person, including changes in movement, behaviour, thinking and speech. As a result, catatonia may be overlooked or mistaken for symptoms of HD. Recognising that catatonia may occur alongside HD is therefore important, as some symptoms of catatonia may improve with appropriate treatment.

When the Lines Become Blurred

However, recognising catatonia in a person with HD is not always straightforward. Both conditions can cause agitation, reduced movement and apathy, which can sometimes be mistaken for changes associated with HD. This can make it difficult to know whether catatonia may also be contributing to the person’s symptoms.

This symptom overlap creates a real diagnostic challenge.  As a result, catatonia may be overlooked unless healthcare professionals are aware of it and actively consider it as a possibility. Although catatonia appears to be uncommon in HD, recognising it is important because people with HD who develop catatonia may require a different treatment approach than those experiencing symptoms caused by HD alone.

Four Cases, Shared Lessons

To better understand more about this overlap, the researchers searched six major medical databases for every published report of catatonia co-occurring in people with HD. Despite decades of HD research, they identified just three publications describing four individuals with both conditions, highlighting just how little is currently known about people with HD who also develop catatonia.

The four people ranged in age from 16 to 62 years, and each had a unique clinical history. Some had juvenile-onset HD, while others developed symptoms later in life. Catatonia also presented differently from person to person, either stuporous catatonia or excited catatonia. All four individuals also experienced psychosis, but there are too few reported cases to know whether psychosis is linked to catatonia in people with HD. 

It is important to remember that while the findings from this study offer an important glimpse into people with HD who also developed catatonia; this is only a starting point. Larger studies are needed to understand more about catatonia in HD and also to establish if there are any links between psychosis and catatonia in people with HD. 

How Was Catatonia Treated?

Although each person’s experience was different, the treatments they received revealed some important patterns. All four people were treated with lorazepam, a medication commonly used by clinicians as the standard starting treatment for catatonia. However, the response varied. 

Another treatment that was administered in all four people was electroconvulsive therapy (ECT). ECT is when a small amount of electric current is sent into the brain for a few seconds which purposefully causes a short seizure to help reset chemical signals. In three of the four reported cases, ECT led to substantial or complete improvement in catatonia symptoms in people with HD. However, one person required maintenance courses of ECT and another person experienced worsening symptoms, highlighting the need for treatment decisions that are tailored to each individual.

The review also raises an important note of caution. While antipsychotic medications are sometimes used to treat psychiatric symptoms (and improve movement symptoms) in HD, the authors suggest that drugs with stronger dopamine-blocking effects may worsen catatonia in some people. However, because only four cases were analysed in this review, the findings suggest that catatonia may be uncommon, although much more research is needed to determine its prevalenceprevalence A figure estimating how many people there are in a particular population who have a certain medical condition. and before firm recommendations can be made.

What Can We Learn from These Cases?

The researchers are careful not to overstate what can be learned from just four cases. We don’t yet know how common catatonia is in people with HD, why it develops, or whether some people are more likely to experience it than others. The apparent link with psychosis is also intriguing, but four cases are far too few to know whether this is a genuine link.

The review also highlights the need for more consistent reporting of future cases. Some of the published reports lacked important information, such as detailed catatonia assessments or test results used to support the diagnosis of catatonia, making it difficult to compare individual cases. 

For now, the most important thing is simply recognising that catatonia can occur alongside HD and may be underdiagnosed or mistaken for other symptoms. Although it appears to be rare, being aware of catatonia as a possibility when symptoms change suddenly or don’t fit the usual picture could help clinicians identify it and consider appropriate treatment.

The lines between HD and catatonia may sometimes be blurred. However, recognising that occasionally there can be more than one explanation for a change in movement symptoms or behaviour could make an important difference to ensure each person with HD is receiving the best treatment.

Summary

• A new review by Dr. Sahil Munjal and colleagues examined the published cases of catatonia occurring alongside Huntington’s disease (HD), focussing on why it can be difficult to recognise and how it has been treated. 
• The review identified just three publications describing four people with both HD and catatonia. The cases varied widely, with both stuporous and excited forms of catatonia reported, and all four people also experienced psychosis, although there were too few cases to conclude whether there are links between catatonia and psychosis in people with HD. 
• All four people received lorazepam, while all four also received electroconvulsive therapy (ECT). ECT led to substantial or complete improvement in catatonia in three cases, although one person needed ongoing ECT and another experienced worsening symptoms, highlighting the need for individualised treatment. 
• The findings highlight the challenge of recognising catatonia in HD because symptoms can overlap with those caused by HD. The authors emphasise the need for greater awareness and further research to understand how common catatonia is in HD, what causes it, and how best to treat it.