Written by Hope Human Services
Washington’s DDA-connected disability support team helping individuals, families, and support staff navigate co-occurring mental illness and intellectual or developmental disabilities with clarity, not guesswork.

Learning how to support someone with mental illness starts with listening and not immediately trying to fix the problem, staying consistent, and knowing when more help is needed. When that person also has an intellectual or developmental disability (I/DD), support may need to be more individualized because communication, emotional expression, and changes in behavior can look different from one person to another. The goal is not to have the perfect response every time; it is to understand the person well enough to notice when something has changed and respond with patience, clarity, and respect.

For a sibling, family, or caregiver, that can feel like a lot of responsibility. You may wonder whether the person you support needs reassurance, space, a change in the environment, professional mental health support, or simply someone who will stay calm beside them.

Key Takeaways

• Mental illness and intellectual or developmental disabilities can occur together.
• Changes in behavior may sometimes communicate emotional or mental health distress.
• Use clear, concrete language and give the person time to respond.
• Listen before jumping into problem-solving.
• Pay attention to changes from the person’s usual patterns.
• Professional or crisis support may be needed when safety or functioning changes significantly.
• Caregivers need support too.

Table of Contents

• What Is Mental Illness Awareness Week, and Why Does It Matter for People With I/DD?
• How Common Is Co-Occurring Mental Illness in People With I/DD?
• How Do You Support Someone With Mental Illness Day to Day?
• How Is Supporting Someone With Dual Diagnosis Different?
• What Should You Avoid Saying or Doing?
• When Should You Seek Professional or Crisis Support?
• How Does Hope Human Services Support People Facing Dual Diagnosis?
• Frequently Asked Questions

What Is Mental Illness Awareness Week, and Why Does It Matter for People With I/DD?

Mental Illness Awareness Week is an annual opportunity to learn more about mental health, reduce stigma, and talk openly about getting support. In 2026, Mental Illness Awareness Week takes place October 4–10, during the first full week of October.

For anyone supporting someone with I/DD, whether a family member, direct support professional, or other caregiver, awareness also means remembering that a developmental disability does not explain every emotional, behavioral, or mental health change. Someone can have an intellectual or developmental disability and also experience anxiety, depression, a mood disorder, or another mental health condition.

That distinction matters when you know someone well. If your sister usually loves going to work but suddenly refuses to leave the house, or your adult son begins sleeping much more than usual and stops engaging in favorite activities, or a resident you support stops joining a weekly outing they used to enjoy, the change deserves attention rather than an automatic assumption that it is simply part of the disability.

Mental Illness Awareness Week can be a reminder to learn the person’s baseline, notice meaningful changes, and make mental health part of the conversation about whole-person support.

How Common Is Co-Occurring Mental Illness in People With I/DD?

Co-occurring mental health conditions are an important concern for people with intellectual disabilities. One systematic review and meta-analysis of 22 studies estimated that 33.6% of adolescents and adults with intellectual disabilities had a co-occurring psychiatric disorder, although estimates varied substantially among studies.

That combination is often described as a dual diagnosis. In this context, dual diagnosis refers to an intellectual or developmental disability occurring alongside a mental health condition.

The numbers matter, but people do not need statistics to tell them when someone they know well seems different. Knowing the person’s usual communication, routines, interests, energy, sleep, and ways of coping can help family members and support staff recognize changes that may deserve a closer look.

Hope Human Services discusses this overlap in more detail in our guide to co-occurring developmental disabilities and mental illness.

How Do You Support Someone With Mental Illness Day to Day?

You can support someone with mental illness day to day by being consistent, listening carefully, and responding to what the person needs rather than assuming you have to solve the problem. Your presence can be useful even when you do not have the perfect words.

Start with simple observations instead of interpretations. “You seem quieter today. Do you want to talk?” may be easier to respond to than “What’s wrong with you?” or “Why are you acting like this?”

Give the person enough time to answer. If verbal communication is difficult, pay attention to other ways they communicate, including gestures, facial expressions, AAC, changes in routine, or familiar behaviors.

You can also offer concrete choices when an open-ended question feels overwhelming. Instead of asking, “What do you need?” you might ask, “Would you like me to sit with you, or would you rather have some quiet time?”

Support does not always mean getting someone to talk. Sometimes it means staying nearby, lowering demands, helping maintain a familiar routine, or letting the person know you are available when they are ready.

How Is Supporting Someone With Dual Diagnosis Different?

Supporting someone with a dual diagnosis can require paying attention to both mental health and disability-related needs instead of assuming one explains everything. Communication differences, sensory needs, difficulty describing internal experiences, or changes in routine may affect how distress is expressed.

For example, someone may not say, “My anxiety has been worse this week.” You might instead notice that they are sleeping differently, avoiding activities they usually enjoy, seeking more reassurance, becoming more withdrawn, or having difficulty with routines that are normally manageable.

That does not mean every behavior change is caused by mental illness. Physical discomfort, environmental stress, communication barriers, changes in support, grief, medication effects, sensory overload, and many other factors can affect how someone feels or behaves.

The important question is often not simply, “What behavior do I need to stop?” A more useful question may be, “What changed, and what might this person be communicating or experiencing?”

What Should You Avoid Saying or Doing?

You should avoid dismissing the person’s feelings, arguing them out of distress, or treating every difficult moment as intentional misbehavior. Even when you do not fully understand what the person is experiencing, you can respond without making them prove that their feelings are real.

Phrases like “Calm down,” “You’re fine,” or “There’s nothing to be upset about” may shut down the conversation. Try something more concrete, such as, “I can see this is hard right now,” followed by a simple question about what would help.

Avoid overwhelming the person with several questions or instructions at once. When someone is already distressed, fewer words and one clear step at a time may be easier to process.

It also helps to avoid turning every hard moment into a lesson. There may be time later to talk about what happened, but the middle of an overwhelming moment is often a time for safety, regulation, and connection rather than correction.

When Should You Seek Professional or Crisis Support?

You should seek professional or crisis support when there is a significant change in the person’s mental health, daily functioning, or safety that cannot be managed with their usual supports. A familiar provider, mental health professional, case manager, or other member of the person’s support network may help you determine the appropriate next step.

If you are worried about suicide or self-harm, take the concern seriously rather than assuming a person with I/DD does not understand or experience those feelings. Hope Human Services has additional information about suicide prevention and recognizing when someone may need help.

If there is an immediate danger or medical emergency, use emergency services. For urgent mental health distress that is not an immediate medical emergency, family members and support staff can also use appropriate local or national crisis resources.

You do not have to wait until you know exactly what is happening before asking for guidance. Saying, “This is different from what I usually see, and I’m concerned,” gives a professional useful information without requiring you to diagnose the problem yourself.

How Does Hope Human Services Support People Facing Dual Diagnosis?

Hope Human Services supports people with intellectual and developmental disabilities by building individualized care around the whole person, including co-occurring mental health needs. Support is not based on the assumption that every person with the same diagnosis needs the same response.

Whether you are a family member or a support professional, that individualized approach matters because you may know the person extremely well while still feeling unsure about how to respond during a difficult period. A support plan can help identify communication preferences, routines, triggers, calming strategies, important changes to watch for, and the professionals or resources involved in the person’s care.

Consistency across family members and support providers can also make difficult periods less confusing. Everyone does not need to use identical words, but it helps when the people involved understand what support looks like for that individual.

Contact Hope Human Services to talk with a team member about support options for yourself, a family member, or someone you support with a dual diagnosis.

Frequently Asked Questions

About Hope Human Services

Hope Human Services provides supported living, disability support, and DDA-connected services for adults and youth with intellectual and developmental disabilities across Pierce, Spokane, and Vancouver/Clark counties in Washington State. The team is experienced with dual diagnosis, co-occurring mental health conditions alongside I/DD, and builds individualized support plans that address both rather than treating one and overlooking the other.

People deserve support that recognizes the whole person and the people who care about them. Contact Hope Human Services to learn more about support options for yourself, a family member, or someone you support with a dual diagnosis.