Intellectual Disability and Other Psychiatric Disorders

Intellectual disability and psychiatric disorders are highly interrelated areas of study within the mental health space. Individuals with intellectual disabilities are at increased risk of psychiatric conditions, which can greatly influence their quality of life and daily functioning. It is important to understand that these conditions are often co-occurring, so we can provide the best care possible and a supportive environment.

ID typically leads to difficulties with cognitive functioning and social and adaptive behaviors; psychiatric disorders may be superimposed on these difficulties. When someone suffers from both conditions at the same time, it is known as a dual diagnosis–and this dual diagnosis often needs a nuanced and collaborative approach to care because each condition can exacerbate the other if left unmanaged. That means families, caregivers, and members of the healthcare team must all work together to make sure the right interventions and support are provided for each individual’s specific needs.

What Is Intellectual Disability?

Intellectual disability means subaverage intellectual functioning (IQ less than 70) and deficits in two or more adaptive behavior skills that negatively affect learning and daily functioning.

Intellectual disability, also referred to as intellectual developmental disorder, occurs when a person has limitations in intellectual functioning and adaptive behavior. These limitations start before the age of 18 and include the ability to communicate, engage in social interaction, or solve problems.^[2]

The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) outlines three primary criteria for diagnosing ID:

1. Deficits in intellectual functioning – This is confirmed by clinical assessment or standardized IQ testing: a person has deficits in intellectual functioning, including reasoning, planning, abstract thinking, judgment, academic learning, and learning from experience.
2. Deficits in adaptive functioning – This includes impairments in adaptive functioning, namely those that impair a person’s capacity to meet the standard developmental and sociocultural requirements for personal independence and social responsibility.
3. Onset during the developmental period – ID must start at or in the developmental period, typically before the age of 18.^[1]

The level of support required varies greatly among those with ID, and the severity of ID ranges from mild to profound.

How Common Are Psychiatric Disorders in Individuals with Intellectual Disabilities?

The research has consistently found that the risk for psychiatric disorders in individuals with ID is significantly greater than in the general population. It is estimated that between 30% and 50% of people with ID also have a co-occurring mental health condition, with some research suggesting even higher rates.^[6]

This elevated prevalence can be attributed to several factors:

1. Biological vulnerabilities – Genetic syndromes associated with ID typically lead to biological vulnerabilities; for example, Down and Fragile X syndromes predispose individuals to psychiatric conditions.
2. Environmental stressors – Mental health challenges experienced by persons with ID may be multifactorial and result from environmental stressors, including experiences of discrimination, social isolation, and lack of access to appropriate care.
3. Communication barriers – Psychological distress is increased due to communication barriers, specifically when it is difficult to express feelings or emotions and ask for help.

Taking into consideration this higher prevalence, it is important to identify and intervene early.

Common Psychiatric Disorders with ID

Some psychiatric disorders are seen more often in individuals with Intellectual disabilities. These include:

1. Anxiety disorders: People with ID often have anxiety, including generalized anxiety disorder, phobias, and obsessive-compulsive disorder. Communication or understanding challenges when talking about new or unpredictable situations may amplify feelings of fear or uncertainty.^[3]
2. Depression: Depression in those with ID often looks different to people without ID. This often includes changes in behavior, such as withdrawal, becoming aggressive, or demonstrating a noticeable decline in adaptive skills.
3. Attention-deficit/hyperactivity disorder (ADHD): Individuals with ID have a higher prevalence of ADHD (inattention, hyperactivity, and impulsivity). This can further impact learning and social relationships.
4. Autism spectrum disorder (ASD): ASD is not itself a psychiatric disorder but can be associated with ID, and its prevalence is associated with higher rates of anxiety, depression, and mood disorders.^[4]
5. Psychotic disorders: These are less common, but they do occur in people with ID, including conditions like schizophrenia, which often manifest with symptoms such as hallucinations, delusions, or disordered thinking.

Diagnosis of Mental Health Conditions in Persons with ID

Diagnosing psychiatric disorders in the ID population is tricky. For ID populations, the standard diagnostic criteria and tools for identifying neuropsychiatric conditions are often not very helpful. Common barriers include:

• Communication challenges: Those with ID may not have a way to express how they feel and may not be diagnosed at all or may be misdiagnosed.
• Diagnostic overshadowing: This occurs when the mental health condition is missed because only symptoms of a psychiatric disorder are attributed to the person’s intellectual disability.^[5]

However, specialized assessment methods to tackle these challenges have already been developed. These include:

• Modified diagnostic tools: For example, the Diagnostic Manual – Intellectual Disability (DM-ID-2) includes criteria specific to those with ID.
• Behavioral observation: Clinicians rely heavily on watching changes in the behavior or on input from the caregiver.
• Collaborative assessment: Multidisciplinary teams, such as psychologists, psychiatrists, and speech therapists, evaluate the child.

The diagnosis can only be treated if it’s accurate and is best treated when it is made timely.

Treating Mental Health Disorders in Individuals with ID

Psychiatric disorder treatment in ID must be individualized to the particular ID strengths, deficiencies, and specific needs of the individual. A combination of approaches often proves most effective:

1. Psychotherapy adaptations:

• Now, adapted traditions of cognitive-behavioral therapy (CBT) have proven more effective. These traditions, such as the use of visual aids, simplified language, and experiential learning techniques, need adjustment for individuals who have ID.^[6]

2. Medication management:

• Psychotropic medications can help people with symptoms of anxiety, depression, or ADHD. However, it’s important to watch these patients closely because side effects or drug interactions with these patients often require many physical health medications as well.

3. Behavioral interventions:

• Techniques like positive behavior support (PBS) focus on figuring out and changing environmental triggers for challenging behaviors. This allows individuals to replace these unhealthy ways of coping with more useful ones.

4. Collaborative care:

• Mental health professionals, primary care providers, and disability specialists working together in a coordinated fashion is the most effective treatment. Care plans have to include family and caregivers for consistency.

How to Support Someone with Intellectual Disability and Psychiatric Disorders

Supporting individuals with ID who have co-occurring psychiatric disorders requires a community-based, compassionate approach. Families, caregivers, and professionals, too, will most benefit when they foster the person’s well-being to help them feel understood and valued.

1. Education and awareness:
   Support persons need to be trained on the signs of mental illnesses and the needs of this person in an individual manner. Individuals who are supporting someone with an ID can benefit from both great resources in the National Alliance on Mental Illness (NAMI) and local or online training workshops.
2. Access to resources:
   Getting families to connect with local support groups, respite care services, and advocacy organizations can help put a safety net under people that will ease stress by creating a support network.
3. Individualized care plans:
   Person-centered planning is utilized so that interventions meet the person’s goals, abilities, and preferences.
4. Fostering inclusion:
   Self-esteem and feelings of belonging are encouraged through participation in social, recreational, and educational activities.
5. Advocacy:
   The larger issue for this population is that systemic changes, such as increasing mental health services and treatment, must be promoted.

When we focus on the strategies mentioned, we can build a supporting ecosystem that ensures the priority is the well-being of individuals with ID, who also face co-emerging psychiatric conditions, along with their families and caregivers.

Conclusion

The co-occurrences of ID and psychiatric disorders represent a difficult combination, but it is one where we may intervene meaningfully. Understanding the needs of this population will help us to improve our diagnostic methods, treatments, and support networks. Inclusion and inclusive education come about as a result of collaboration between professionals, families, and the wider community, who together are able to create an environment that is beneficial to individuals with ID and psychiatric disorders.