Hoarding Disorder Research: What Studies Tell Us About Hoarding

Research into hoarding has changed considerably over the past few decades. What was once commonly discussed mainly as a form of obsessive-compulsive behaviour is now recognised as a distinct mental-health condition with its own patterns, challenges and areas of study.

Important: This article summarises broad findings from hoarding research for educational purposes. It is not medical advice and cannot diagnose Hoarding Disorder.

How our understanding of hoarding has changed

Older descriptions of compulsive hoarding often discussed it primarily in connection with obsessive-compulsive disorder, or OCD.

Over time, research showed that hoarding could occur as a distinct pattern with its own characteristic difficulties.

Modern diagnostic systems therefore recognise Hoarding Disorder separately, although someone can experience Hoarding Disorder alongside OCD or other mental-health difficulties.

This distinction has been important because it has encouraged researchers to study hoarding specifically rather than assuming that findings about OCD automatically apply to it.

What are researchers trying to understand?

Hoarding research covers a wide range of questions.

Some of the main areas include:

why people develop persistent difficulty discarding possessions
why some possessions become unusually important
how decision-making and organisation may be involved
why acquiring becomes excessive for some people
how clutter affects daily functioning
the role of avoidance and distress
how hoarding develops across the lifespan
which forms of treatment and support are most effective

Difficulty discarding is central

One of the most consistent features identified in research is persistent difficulty discarding or parting with possessions.

The difficulty is not necessarily related to the financial value of an item.

A possession may feel important because it seems useful, carries memories, represents responsibility, or creates anxiety about making the wrong decision.

Researchers have therefore looked at the beliefs and emotions attached to possessions rather than focusing only on the physical amount of clutter.

Attachment to possessions

Research has examined why objects may carry unusually strong emotional meaning for some people.

Possessions can sometimes become closely connected with identity, memory, security or responsibility.

This helps explain why a family member may see an object as disposable while the person keeping it experiences letting go as genuinely difficult.

The object itself may appear ordinary. The meaning attached to it may not be.

Decision-making and organisation

Another important area of research concerns how people make decisions about possessions.

Sorting a cluttered room can involve hundreds or thousands of individual choices:

Do I need this?
Will I regret throwing it away?
Where should it go?
Could somebody else use it?
Is this the right time to decide?

If every decision feels unusually important or difficult, sorting can become mentally exhausting.

Research has therefore examined cognitive processes such as categorisation, attention, memory and decision-making as possible contributors to hoarding-related difficulties.

Avoidance can help maintain the problem

One pattern researchers have examined is avoidance.

If deciding whether to discard an object creates distress, postponing the decision provides immediate relief.

The object remains, the difficult decision disappears for the moment, and the person feels better temporarily.

But the decision has not actually been resolved.

When this happens repeatedly, possessions can accumulate while the task of sorting becomes larger and increasingly overwhelming.

Acquiring is another part of the picture

Difficulty discarding explains why possessions stay, but it does not explain why new possessions continue to arrive.

Research therefore also looks at excessive acquiring.

This can include shopping, collecting free items, accepting other people’s unwanted possessions or feeling unable to leave potentially useful objects behind.

Not everyone with Hoarding Disorder experiences excessive acquiring to the same degree, but for some people it is a major contributor to increasing clutter.

Clutter is important, but clutter alone is not enough

Visible clutter is one of the most obvious features associated with severe hoarding.

However, researchers and clinicians do not determine Hoarding Disorder simply by looking at a photograph of a room.

A home can become cluttered for many reasons.

Assessment therefore considers a broader pattern involving difficulty discarding, distress, accumulation and the extent to which living areas can still be used normally.

You can read more about this on our Hoarding Disorder: Signs, Symptoms and Assessment page.

How researchers measure clutter

Several tools have been developed to study different aspects of hoarding.

Some focus on visible clutter, while others look at difficulty discarding, acquiring, distress and interference with normal life.

Visual clutter-rating methods can help people compare rooms with increasingly cluttered reference images.

Our article on the Hoarding Rating Scale 1–9 explains this approach in more detail.

These tools are useful for structuring observation and research, but no single image or score should be treated as a diagnosis on its own.

What does research say about the causes of hoarding?

There is no single proven cause that explains every case of Hoarding Disorder.

Research has explored a combination of possible influences, including:

genetic vulnerability
cognitive and information-processing differences
beliefs about possessions
emotional attachment to objects
avoidance
personality factors
life experiences and environmental influences

Current research suggests that these factors may interact rather than one single factor causing hoarding in everyone.

Does hoarding begin suddenly?

Research commonly describes hoarding as a pattern that can develop gradually.

Difficulties with saving possessions may begin relatively early, while serious clutter and functional problems can become more noticeable later as belongings accumulate over time.

This gradual development can make change difficult to notice because the person sees the same environment every day.

Research into older adults

Older adults are an important area of hoarding research because the practical consequences of severe clutter can become more serious when mobility, health or independence are also affected.

Researchers have examined relationships between hoarding, daily functioning, physical health and cognitive functioning in later life.

This is also an area where researchers continue to note gaps in evidence and the need for more targeted studies.

What has research found about treatment?

Specialised cognitive behavioural approaches have become an important focus of treatment research.

These approaches may work with areas such as:

decision-making
beliefs about possessions
practising discarding
reducing unnecessary acquiring
organising possessions
gradually restoring usable living space

Research has also explored group-based, peer-supported and remotely delivered approaches.

Results have been encouraging in some studies, but researchers continue to investigate how treatment can be made more effective and accessible.

For a broader overview, see our Hoarding Disorder Treatment and Support Options article.

Why “just clear the house” is too simple

Research has helped show why hoarding cannot be understood solely as a cleaning problem.

Removing possessions may change the appearance of the home, but it does not necessarily change the difficulty discarding, emotional attachment, acquiring or avoidance that contributed to the clutter.

This is one reason modern approaches tend to look at both the physical environment and the psychological processes surrounding possessions.

There are still important unanswered questions

Research into Hoarding Disorder has advanced substantially, but important questions remain.

Researchers are continuing to study:

why some people develop severe hoarding while others do not
which factors are most important for different individuals
how to improve treatment outcomes
how best to support people who do not seek help themselves
how families and communities can respond to severe cases
how hoarding changes across different ages and circumstances

That means research should be understood as an evolving body of evidence rather than a final explanation of every person’s experience.

What does your own clutter pattern look like?

Our self-reflection assessment looks separately at clutter, difficulty discarding, acquiring possessions and the impact these patterns may be having on everyday life.

Take the Hoarding & Clutter Assessment

For education and personal reflection only. It does not diagnose Hoarding Disorder or provide medical advice.