Mirror, Mirror on the Wall: When Self-Awareness Shifts in Huntington’s Disease

We don’t come to know ourselves in isolation. Our understanding of who we are develops over time through what we notice internally and through feedback from others. For example, a friend might point out that you have been quieter than usual lately. It is these small signals that gradually help us adjust and refine our sense of self.

Most of the time, our inner beliefs and what others reflect back to us are fairly aligned, which helps us to feel that we understand ourselves clearly. However, in Huntington’s disease (HD), these internal and external reflections can become less consistent and may not match as closely. A recent study by Professor Jody Corey-Bloom and her team in San Diego, California, explored how symptom awareness can begin to change even in the early stages of HD.

Measuring Distorted Reflections

Some people with HD have reduced awareness of their own symptoms, known as anosognosia. To study this, researchers recruited 60 people with HD, as well as their study partners (a close companion or caregiver), and asked them to complete the Anosognosia Scale. 

This is a survey in which participants rated their ability to carry out everyday activities, including physical movements, thinking skills and managing emotions. Their study partners also completed a similar survey, rating the person’s abilities from their point of view. 

This “two-mirror” approach allowed the researchers to compare people’s own experiences of HD symptoms with their companions’ observations of those same symptoms. Statistical analysis was used to examine whether differences between these two perspectives were large enough to suggest reduced symptom awareness (anosognosia). Anosognosia is typically identified when self-ratings and companion ratings are very different. It is important to note that people could overestimate changes in symptoms, as well as underestimating them.

When Do Distorted Reflections Occur?

Participants were grouped using an estimated Huntington’s Disease Integrated Staging System (HD-ISS) score, based on their performance on other surveys and tasks. The HD-ISS is a way that scientists divide Huntington’s disease into four stages (0-3) based on biology and subtle changes in the brain and body, not just visible symptoms. It helps researchers track the disease from its earliest beginnings. For more information on HD-ISS categories, see our article about this system. In this study, the HD-ISS enabled the researchers to investigate when anosognosia tends to emerge as HD progresses.

It is important to note that people in HD-ISS stages 0 and 1 were combined in this study. Distinguishing between these two early stages typically requires brain scans, which participants did not undergo. 

What Did the Mirrors Reveal?

In this study, anosognosia was present across all stages of HD, among the participants included. This underestimation of symptoms was seen in 18% of people in Stages 0/1, rising to 28% in Stage 2, and reaching 32% in Stage 3. It is important to remember that while these findings offer valuable insight, they come from a small sample of people with HD, and it is not yet clear how well they reflect the broader global HD community.

Reflecting on the Findings

This study suggests that a person with HD may not always have a fully accurate reflection of their own symptoms, regardless of HD stage. It’s a bit like looking into a distorted carnival mirror that warps the image that it reflects back. 

In the same way, people’s own accounts of their symptoms may not fully capture certain difficulties. These can sometimes be more clearly seen from the outside, like a friend standing beside you and noticing changes that aren’t as obvious to the person with HD.

A Clearer Image for Future Research

Finding that people with HD might lose some self-awareness of symptoms, even early on, has practical implications for future HD research. Currently, many clinical trials rely on surveys where people with HD rate their own symptoms. 

However, if someone’s “internal mirror” is a bit foggy, they might unintentionally underestimate their symptoms. This means that survey results may not always reflect the true picture, potentially affecting the accuracy of clinical trial results. This is because many trials rely on patient responses to surveys as measures of how their condition is progressing.

To ensure new treatments from clinical trials are truly working, future studies may need to pair these surveys with observations from close companions. This could help to build a more complete view of any changes in a person’s symptoms over time.

Seeing Past Assumptions

Anosognosia is often misunderstood as denial or a refusal to accept illness. However, it is a reduced awareness of one’s own symptoms, and it is relatively common in people with HD.

This distinction matters, particularly in how families and clinicians interpret behaviour. If an individual does not recognise a symptom, it is not necessarily because they are resisting or dismissing what others are saying. Instead, it may reflect changes in the brain systems that normally help us notice and make sense of change in ourselves.

Through the Looking Glass: A Hopeful Outlook

This study suggests that reduced awareness of symptoms in people with HD may begin earlier in the condition than previously thought. While that may seem unsettling at first, it could bring us closer to understanding the fuller picture of how HD affects each individual.

Better understanding of anosognosia can also help improve clinical trials. If researchers know that self-awareness of symptoms may be affected, they can take this into account when designing studies and interpreting results, leading to more accurate and meaningful findings. 

However, it is important to remember that this work is an early step. Larger studies, involving more diverse groups of people, are still needed to confirm how widely these patterns apply across the HD community. 

Taken together, these findings highlight that understanding symptom progression in HD requires more than one perspective. To build the clearest picture, we need to bring together “lenses” from the person with HD, from caregivers, and from clinicians, so that changes are less likely to be missed or misunderstood.

Summary

• A UCSD study involving 60 people with HD, as well as their caregivers, investigated awareness of symptoms in people at different stages of HD.
• The findings showed that in some cases, people reported fewer or less severe symptoms than were observed by others, suggesting reduced awareness (anosognosia) may appear early in HD.
• This mismatch between self and external reports highlights the importance of considering multiple perspectives when assessing symptoms in HD.
• The study suggests that self-reported outcomes alone may not always provide a complete picture in both clinical practice and research, particularly in early stages of disease.
• These findings support the inclusion of caregiver or clinician input alongside patient reports to improve accuracy in understanding symptom progression in HD.