Mental Health Awareness and Intellectual and Developmental Disability (IDD) - Valley Behavioral Health
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May 18, 2020 By Julia Hood, Ph.D., BCBA, NCSP

May is Mental Health Awareness month and the goal of recognizing this month is to increase awareness around various mental health needs, reduce stigma around mental health, and increase access to services.  There is a subset of people with a dual diagnosis who sometimes struggle to receive appropriate diagnosis and treatment.  Usually, dual diagnosis refers to individuals with a mental health diagnosis and a substance use disorder diagnosis.  In this instance, dual diagnosis refers to someone who has a mental health or a substance use disorder diagnosis and also has a diagnosis of an Intellectual and Developmental Disability (IDD) This blog will specifically address this group of individuals who have IDD and a mental health/substance use diagnosis.

What is IDD Diagnosis?

First, I want to define what IDD is so that there is an awareness of what it is and who is considered to have an IDD diagnosis.  Intellectual disability is present before the age of 18 and individuals have deficits in intellectual functioning and adaptive functioning as evidenced by standardized testing.  Developmental disabilities are also present in childhood, are typically lifelong diagnoses, and can affect people in the areas of physical, learning, language, or behavior.  These can include Attention Deficit Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD), Cerebral Palsy, hearing loss, Learning Disability (LD), vision impairment, other developmental delays.

Typically, IDD refers to individuals who have both an intellectual disability and a developmental disability.  About one in six, or about 17%, of children aged 3 through 17 years have one or more developmental disabilities.  Individuals with IDD are at a higher risk of also having a mental health diagnosis.  The general population has a prevalence of about 19% of all adults who have a mental health diagnosis, but the prevalence of adults with IDD who also have a mental health diagnosis is around 34%, more than 50% have mental health and/or a substance use diagnosis.  There is a great need to help increase awareness and treatment for people with this type of dual diagnosis.

IDD and Mental Health

Despite the high rates of co-occurring mental health and IDD, there is often a barrier to these individuals accessing appropriate diagnosis and treatment.  Many times, the mental health diagnosis is missed and not treated due to the IDD diagnosis or vice versa.  One of the barriers to individuals receiving a diagnosis of IDD is that it requires standardized testing of cognitive and adaptive abilities by a psychologist before a diagnosis can be given.  Many therapists are not comfortable diagnosing Autism Spectrum Disorder (ASD) if they do not have extensive experience with this diagnosis.    Other barriers identified by Mcgilvery & Sweetland, 2012 include:

·       Diagnostic overshadowing – assuming behaviors that may be symptoms of psychiatric diagnosis is part of the IDD

·       Medication masking – medications minimizing symptoms of a psychiatric diagnosis

·       Communication deficits – the individual doesn’t accurately report symptoms due to communication deficits

·       Atypical presentation of psychiatric disorders – some diagnoses present slightly different in individuals with IDD

·       Medical conditions – some symptoms may be assumed to be due to a medical condition instead of the psychiatric diagnosis

·       Episodic presentation – symptoms are not currently present, so not detected at the time of assessment

Why are these diagnoses important?  If you have a client with schizophrenia, bipolar, anxiety, or some other mental health diagnosis, a co-occurring diagnosis of IDD can have implications for appropriate treatment.  There is a misconception that individuals with IDD don’t benefit from mental health treatment, when in fact treatment can be highly effective with some adaptations to mental health treatment for individuals who also have IDD.  Some best practices for modifications identified in Fletcher, 2011 include:

·       Making changes based off of language level

·       Frequency of sessions

·       Length of sessions

·       Duration of therapy

·       Using a more structured and direct approach

·       Providing information in multiple ways instead of just verbally

·       Modify the complexity of interventions

·       Therapist needs to be flexible and supportive

It can also be really helpful to provide some visual supports or written information to help reinforce what is talked about verbally.  Providing training on coping skills and self-management can be very useful and can be adapted to the needs of each client based on their diagnoses and behaviors.

Many people with IDD are more isolated from the community and often still have parents as caregivers and guardians once they reach adulthood.  When they do access to the community, they can sometimes feel judged or avoided by others.  Often there is a belief that they don’t understand because of their language and intellectual levels, but I encourage you to not make that assumption.  Many people with IDD very much understand even if they can’t effectively communicate that and their feelings also get hurt just like everyone else.  They are very aware of how people react toward them or talk about them in front of them, so please be respectful when interacting with or around someone with IDD.




Fletcher, R.J. & Reiss, S.  (2011).  Psychotherapy for individuals with intellectual disabilities.  National Association For The Dually Diagnosed.

McGilvery, S. & Sweetland, D. (2012).  Intellectual disability and mental health: A training manual in dual diagnosis.  National Association For The Dually Diagnosed.

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