Understanding Dual Diagnosis in Developmental Disabilities and the Role of Positive Systems Approach
- drbobcarey
- Apr 7
- 10 min read
What is Dual Diagnosis in the Developmental Disability Field?
In the Developmental Disability field, dual diagnosis refers to the co-occurrence of a developmental disability (DD) and a mental health disorder in an individual. Unlike other medical or psychiatric conditions that may exist separately, dual diagnosis requires an integrated approach that considers both the cognitive and behavioural challenges associated with developmental disabilities and the emotional and psychological complexities of mental illness.
Individuals with developmental disabilities often experience conditions such as autism spectrum disorder, intellectual disability, or cerebral palsy. When these individuals also have mental health disorders such as depression, anxiety, bipolar disorder, schizophrenia, or obsessive-compulsive disorder, they are classified as dually diagnosed. The interplay between these conditions often exacerbates behavioural and emotional challenges, making diagnosis, treatment, and support particularly complex.
Prevalence of Dual Diagnosis in Developmental Disabilities
The prevalence of dual diagnosis in the developmental disability field is significant yet often underestimated. Studies have found that approximately 30% to 50% of individuals with developmental disabilities also have a co-occurring mental health disorder. For instance, a systematic review and meta-analysis reported a pooled prevalence of 33.6% for any co-occurring psychiatric disorder among individuals with intellectual disabilities. Similarly, another review focusing on children and adolescents with intellectual developmental disorders found that the rate of co-occurring mental disorders ranged from 30% to 50%. Additionally, data from the National Core Indicators-In Person Survey indicated that 44.8% of individuals with intellectual and developmental disabilities had co-occurring mental health conditions. These findings underscore the significant prevalence of mental health challenges among individuals with developmental disabilities and the necessity for specialized care and intervention strategies.
Challenges in accurately identifying dual diagnosis arise because symptoms of mental illness may manifest differently in individuals with developmental disabilities. For example, anxiety may not present through verbal expression but rather through aggressive behaviours or self-injury. Consequently, many individuals remain undiagnosed or misdiagnosed, leading to inadequate or inappropriate treatments.
Importance of Accurate Diagnosis and Challenges in Psychiatric Assessment
Accurate diagnosis of psychiatric disturbances in developmentally disabled individuals is crucial for effective treatment. However, several inherent difficulties complicate this process, including:
Diagnostic Overshadowing: This occurs when symptoms of mental illness are mistakenly attributed to the individual’s developmental disability rather than recognized as a separate psychiatric condition. For example, a person with autism exhibiting withdrawal and loss of interest in activities may be assumed to be displaying core autistic traits rather than signs of depression.
Communication Barriers: Many individuals with developmental disabilities have limited verbal skills, making it difficult for them to articulate feelings of distress, anxiety, or mood changes. This can lead to misinterpretation of their symptoms.
Behavioural Manifestations: Psychiatric symptoms often present differently in individuals with developmental disabilities. Instead of verbalizing distress, they may express their discomfort through aggression, self-harm, or withdrawal, which can lead to a misdiagnosis of a behavioural disorder rather than a psychiatric condition.
Lack of Specialized Training: Many healthcare providers are not trained to differentiate between behaviours stemming from a developmental disability and those indicative of a co-occurring mental health condition, leading to inappropriate treatment plans.
Given these challenges, it is essential for clinicians and caregivers to use thorough assessments, including structured interviews, behavioural observations, and input from family members or caregivers, to accurately diagnose psychiatric conditions in individuals with developmental disabilities.
Below is a decision tree that can help navigate the process for making a determination of dual diagnosis:
Dually Diagnosed Decision Tree
Start:
Does the individual have a diagnosed developmental disability (e.g., intellectual disability, autism spectrum disorder)?
❌ No → Not dually diagnosed (may still have MH concerns).
✅ Yes → Go to step 2.
Are there changes or concerns in the individual's behavior, mood, or functioning that are not fully explained by their developmental disability?
❌ No → Monitor; not likely dually diagnosed at this time.
✅ Yes → Go to step 3.
Are the behavioral/emotional changes consistent across multiple environments (home, school, work)?
❌ No → Consider environmental factors first; observe.
✅ Yes → Go to step 4.
Are symptoms persistent (lasting weeks or more), and do they represent a change from the individual’s baseline?
❌ No → Possibly situational or behavioral; monitor.
✅ Yes → Go to step 5.
Do symptoms meet DSM-5/ICD diagnostic criteria for a specific mental health condition (e.g., anxiety, depression, schizophrenia)?
❌ No → Consider psychological evaluation and functional assessment.
✅ Yes → Go to step 6.
Have physical/medical causes (e.g., pain, medication side effects, sleep issues) been ruled out or addressed?
❌ No → Refer for medical evaluation.
✅ Yes → Go to step 7.
Has a qualified mental health professional (preferably with DD experience) conducted an evaluation?
❌ No → Refer for MH assessment.
✅ Yes → Go to step 8.
Did the professional conclude that the individual meets criteria for a mental health diagnosis?
❌ No → Not currently dually diagnosed; reassess as needed.
✅ Yes → ✅ Individual is dually diagnosed.
A graphic representation of this follows below:
Adjunctive Medication Therapy for Dual Diagnosis
Once an accurate diagnosis has been established, adjunctive medication therapy can play a critical role in managing psychiatric symptoms in dually diagnosed individuals. While behavioural interventions remain essential, medication can be an important tool in stabilizing mood, reducing anxiety, and managing symptoms that interfere with daily functioning.
The use of psychotropic medication in individuals with developmental disabilities should be guided by the following principles:
Individualized Treatment Plans: Medication should be tailored to the individual's specific symptoms and needs, rather than applying a one-size-fits-all approach.
Careful Monitoring: Individuals with developmental disabilities may have atypical responses to medication, necessitating close monitoring for efficacy and side effects.
Combination with Behavioural Strategies: Medication should not be used as a standalone treatment but rather as part of a comprehensive approach that includes behavioural and environmental modifications.
Minimizing Polypharmacy: Many individuals with dual diagnosis are prescribed multiple medications, increasing the risk of side effects and interactions. A conservative approach that minimizes unnecessary medication is recommended.
Commonly used medications include:
Antidepressants (e.g., SSRIs) for mood disorders and anxiety
Mood stabilizers for bipolar disorder
Antipsychotic medications for severe behavioural disturbances or psychotic symptoms
Anxiolytics for severe anxiety-related behaviours
By ensuring accurate diagnosis and appropriate medication management, individuals with dual diagnosis can achieve improved emotional regulation, reduced behavioural challenges, and an overall better quality of life.
Impact on Agencies Supporting Dually Diagnosed Individuals
Agencies that provide services to individuals with developmental disabilities face considerable challenges when supporting those with dual diagnosis. These challenges include:
Complexity of Needs: Individuals require tailored interventions that address both developmental and mental health aspects, necessitating interdisciplinary collaboration between medical (i.e. – psychiatry), behavioural, and social service professionals.
Training and Expertise: Many direct support staff and caregivers lack adequate training in mental health interventions, making it difficult to recognize symptoms and apply effective strategies.
Increased Crisis Situations: Individuals with dual diagnosis may be prone to behavioural crises, requiring crisis intervention strategies that are both effective and non-punitive.
Resource Allocation: Supporting dually diagnosed individuals often requires greater staff time, increased funding, and specialized programs, putting a strain on agency resources.
Systemic Barriers: The separation of developmental disability services and mental health services in many healthcare systems creates fragmented care, leading to delays in diagnosis and inadequate support.
Given these challenges, agencies need a structured, comprehensive framework for addressing the needs of individuals with dual diagnosis. The Positive Systems Approach (PSA) provides such a framework.
Why Positive Systems Approach (PSA) is Ideal for Dual Diagnosis
Positive Systems Approach, as described in our book Managing Disruptive Behaviours with a Positive Systems Approach, is an evidence-based framework designed to support individuals with complex behavioural and emotional needs in a way that promotes dignity, positive outcomes, and systemic change. PSA is particularly well-suited to dual diagnosis cases for the following reasons:
Identification: In the Positive Systems Approach (PSA), the "Identification" component is crucial for recognizing and understanding the role of mental health issues in individuals with a dual diagnosis. This component emphasizes a comprehensive assessment of both observable behaviours and underlying factors—psychological, social, and biological—that contribute to these behaviours. A key aspect of "Identification" is acknowledging that behaviour serves as a form of communication. By interpreting behaviours in this context, practitioners can uncover unmet needs or distress signals, particularly those stemming from mental health challenges.
Furthermore, PSA underscores the importance of cultural factors in behaviour assessment. Cultural backgrounds influence perceptions of mental health and behavioural norms. Integrating cultural understanding into the "Identification" process ensures that assessments are accurate, and interventions are culturally sensitive. The "Identification" component in PSA is vital for accurately assessing individuals with dual diagnoses. It ensures that mental health issues are thoroughly considered, leading to more effective and personalized support strategies.
Holistic Perspective: PSA integrates multiple aspects of an individual's life, including their cognitive abilities, emotional state, social environment, and personal history.
Behaviour as Communication: PSA emphasizes that challenging behaviours are a form of communication. Instead of punitive responses, it encourages understanding the underlying causes of behaviours and addressing them constructively.
Structured, Predictable Support: PSA relies on clear expectations, structured environments, and consistent routines to reduce anxiety and prevent behavioural escalation.
Skill Development: Rather than merely managing symptoms, PSA focuses on developing coping skills, emotional regulation, and social competence in individuals with dual diagnosis.
Support for Caregivers and Agencies: PSA equips agencies and caregivers with the tools and strategies they need to provide effective, sustainable support.
Case Study: Navigating Dual Diagnosis and Achieving Success Through Positive Systems Approach
Introduction Diagnosing and treating individuals with a dual diagnosis presents unique challenges, as symptoms of developmental disabilities can overlap with psychiatric conditions, leading to misdiagnosis or delayed treatment. This case study examines the journey of Alex, a 19-year-old diagnosed with Autism Spectrum Disorder (ASD) and co-occurring Generalized Anxiety Disorder (GAD), and how the Positive Systems Approach (PSA) was instrumental in achieving a favourable outcome.
Case Background Alex was diagnosed with ASD at the age of five. Throughout childhood, he exhibited rigid thinking patterns, social difficulties, and sensory sensitivities. By adolescence, he experienced persistent worry, difficulty sleeping, and overwhelming anxiety about school and social interactions. His challenges were initially attributed to his autism, delaying proper identification of his anxiety disorder. The late recognition of GAD resulted in increased frustration, isolation, and academic struggles.
When Alex turned 19, his struggles intensified. He exhibited extreme avoidance behaviours, refused to attend social gatherings, and expressed feelings of hopelessness. He often engaged in repetitive questioning about future events and displayed excessive distress over minor changes. His support team, including family members, educators, and therapists, sought a comprehensive approach to address his complex needs.
Challenges in Diagnosing the Psychiatric Disorder The biggest hurdle in Alex’s case was distinguishing symptoms of ASD from those of GAD. Key challenges included:
Symptom Overlap: Social withdrawal and difficulty with transitions could be attributed to either ASD or anxiety.
Communication Barriers: Alex struggled to articulate internal emotional distress, leading to assumptions that his behaviours were simply autistic traits rather than signs of a mental health disorder.
Misattribution of Symptoms: His repetitive questioning and rigidity were initially viewed as ASD-related perseveration rather than manifestations of anxiety.
Treatment Hesitation: Many professionals lacked experience in treating psychiatric disorders in individuals with developmental disabilities, leading to hesitancy in prescribing mental health interventions.
Implementing the Positive Systems Approach To address Alex’s complex needs, a Positive Systems Approach (PSA) was implemented. PSA is a structured method involving collaboration, individualized support, and systematic interventions. Below are the key components of PSA and their application in Alex’s case:
Comprehensive Assessment and Multi-Disciplinary Collaboration
A thorough assessment was conducted by a team including a psychiatrist, psychologist, occupational therapist, and special education consultant.
Standardized tools such as the Anxiety Scale for Children with Autism Spectrum Disorder were used to differentiate anxiety from ASD symptoms.
Family members provided critical observations, ensuring that assessment captured Alex’s behaviours in multiple environments.
Person-Centered Planning
Alex was involved in his treatment planning to ensure strategies were aligned with his preferences and strengths.
His personal goals included increasing independence, managing anxiety in social situations, and improving communication about his emotions.
A visual schedule and structured routine helped reduce anticipatory anxiety.
Skill-Building and Cognitive-Behavioural Therapy (CBT)
CBT techniques were adapted to accommodate Alex’s concrete thinking style, using visual supports and step-by-step instructions.
He learned to identify anxiety triggers, develop coping strategies, and practice relaxation techniques such as deep breathing and progressive muscle relaxation.
Role-playing was used to prepare for social situations that triggered anxiety.
Environmental Modifications and Sensory Support
A quiet, low-stimulation environment was created at home and school to minimize sensory overload.
Noise-canceling headphones were provided to reduce distress caused by background noise in social settings.
A sensory toolkit, including fidget objects, was introduced to help self-regulate emotions.
Family and Caregiver Training
Alex’s family and caregivers received training on how to differentiate between ASD-related behaviours and anxiety symptoms.
They learned to reinforce positive coping strategies and avoid unintentionally reinforcing anxiety-driven avoidance behaviours.
A structured response plan was developed to handle meltdowns in a way that minimized stress and promoted emotional regulation.
Community and School Involvement
Educators were informed about Alex’s needs and received training on how to support him in a classroom setting.
Social support groups for individuals with ASD and anxiety were introduced to provide peer interactions in a controlled, low-pressure environment.
Internship and volunteer opportunities were arranged to help Alex build independence in real-world settings.
Medication Management (When Necessary)
After careful consideration, a low-dose selective serotonin reuptake inhibitor (SSRI) was prescribed to help manage Alex’s anxiety symptoms.
Medication was introduced alongside behavioural interventions, with regular monitoring to assess its effectiveness and any side effects.
Outcome and Success Indicators The implementation of PSA led to significant improvements in Alex’s well-being and daily functioning. Key outcomes included:
Increased Emotional Awareness: Alex became better at recognizing and verbalizing his emotions.
Reduction in Avoidance Behaviours: He began attending social events with planned coping strategies in place.
Improved Academic Performance: With anxiety management techniques, he was able to focus better during exams and complete assignments without excessive distress.
Greater Independence: Alex developed skills to manage his anxiety in various environments, reducing dependence on caregivers.
Enhanced Family Dynamics: His family felt more equipped to support him effectively, reducing stress and improving overall interactions.
Diagnosing and treating individuals with a dual diagnosis requires a comprehensive, collaborative, and individualized approach. The Positive Systems Approach proved essential in addressing Alex’s unique needs, ensuring that his developmental disability and mental health disorder were both appropriately managed. By integrating multiple support systems and tailoring interventions to his strengths and challenges, Alex achieved a more fulfilling and independent life. This case study highlights the importance of early identification, interdisciplinary collaboration, and personalized strategies in achieving favorable outcomes for individuals with dual diagnoses.
Conclusion
Dual diagnosis presents unique challenges for individuals, caregivers, and agencies. The Positive Systems Approach provides a structured, compassionate, and effective framework for managing these challenges. By focusing on holistic assessment, individualized support, and skill development, PSA not only reduces disruptive behaviours but also enhances the overall well-being of individuals with dual diagnosis.
For agencies seeking a sustainable and effective approach to dual diagnosis, PSA offers the tools needed to create meaningful change. Through continued application and refinement of this method, we can ensure that individuals like Alex receive the support they need to thrive.
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