What Role Do Genes Play in Hoarding Disorder?

What you need to know

• Hoarding behaviors appear to run in families and are influenced by genetic factors
• The study found that genetic risk factors for schizophrenia and autism spectrum disorder were associated with hoarding symptoms
• Between 26-48% of hoarding tendencies can be attributed to genetic factors

Understanding Hoarding Disorder

Hoarding Disorder (HD) is a mental health condition where people have persistent difficulty discarding or parting with possessions, regardless of their actual value. This results in cluttered living spaces that interfere with their intended use and causes significant distress or problems in daily life. About 1-2.5% of the population has HD, though up to 6-9% may experience some hoarding symptoms.

The symptoms typically begin in early to mid-adolescence and, unusually for a mental health condition, tend to become more severe with age. While we know that hoarding behaviors run in families, we are still learning about the specific genetic and environmental factors that contribute to the disorder.

What This Study Did

This research combined data from seven different studies across Sweden, the Netherlands, England, and Canada, including over 27,000 people in total. Rather than looking only at people diagnosed with Hoarding Disorder, the researchers examined hoarding symptoms across the general population, using questionnaires that asked about behaviors like difficulty discarding items and excessive acquisition of possessions.

The researchers conducted what’s called a genome-wide association study (GWAS), which looks across a person’s entire genetic code to find variations that might be associated with certain traits or conditions. They also analyzed how genetic risk scores for other mental health conditions might relate to hoarding symptoms.

Key Findings

Genetic Influence on Hoarding

The study found that genetic factors account for between 26-48% of the variation in hoarding symptoms among twins. This means that while genes play an important role, environmental factors are also significant in determining whether someone develops hoarding behaviors.

Links to Other Conditions

One of the most interesting findings was that people with genetic risk factors for schizophrenia or autism spectrum disorder were more likely to have hoarding symptoms. There was also some evidence suggesting a connection with educational attainment, though this relationship was less clear.

Surprisingly, the study did not find significant genetic connections between hoarding and other conditions that often co-occur with it, such as:

• Obsessive-compulsive disorder (OCD)
• Depression
• Anxiety
• Attention-deficit/hyperactivity disorder (ADHD)

However, this might be due to limitations in the study’s size rather than a true lack of connection.

Looking at Specific Genes

While the study identified some genetic regions of interest, particularly one involving a gene called SOX5 that has been linked to various psychiatric conditions, no single genetic variation reached the level of statistical significance typically required in genetic studies. This suggests that, like many mental health conditions, hoarding likely involves complex interactions between multiple genes rather than a single genetic cause.

Conclusions

• Hoarding symptoms are moderately heritable, confirming previous research showing that genes play an important role
• There appear to be genetic connections between hoarding and both schizophrenia and autism spectrum disorder
• Larger studies are needed to identify specific genetic variations that contribute to hoarding behaviors
• Future research should include more diverse populations and people with diagnosed Hoarding Disorder to get a complete picture of the genetic factors involved