Dual Diagnosis/ Co-occurring Disorders: Definition, Symptoms, Causes, and Treatment

Dual diagnosis involves the simultaneous occurrence of a mental health disorder and a substance use disorder in the same individual. These conditions interrelate with each other, complicating diagnosis and treatment. Common examples include the coexistence of depression and alcoholism or anxiety and opioid addiction.

The main symptoms of dual diagnosis or co-occurring disorders include persistent sadness, extreme mood swings, anxiety, hallucinations, paranoia, impulsive behaviors, and difficulty managing relationships and responsibilities. 

According to a study, “Mental Illness and Drug Addiction May Co-occur Due to Disturbance in Part of the Brain,” by the American Psychological Association (2007), at least 50% of those seeking help for addiction or mental health treatment have co-occurring disorders.

The causes of dual diagnosis are genetic predispositions, brain chemistry imbalances, early brain injuries, exposure to chronic stress or trauma, social environment factors, poor support systems, self-medication, personality traits, and lack of access to integrated care.

Treatment for dual diagnosis comprises behavioral therapies, medications, and support services such as medically assisted treatment (MAT), support groups, and inpatient and outpatient rehab programs.

What Is Dual Diagnosis/Co-occurring Disorders?

Dual diagnosis, also known as co-occurring disorders, is a type of mental health condition characterized by the simultaneous presence of both a mental health disorder and a substance use disorder in an individual. This complex interplay between mental health and substance use presents unique challenges and requires an integrated approach to treatment.

A mental health disorder affects a person’s thinking, feelings, mood, ability to relate to others, and daily functioning. A substance use disorder (SUD) is characterized by the compulsive use of a substance (such as drugs or alcohol) despite harmful consequences.

A study by the American Psychological Association (2007), titled “Mental Illness and Drug Addiction May Co-occur Due to Disturbance in Part of the Brain,” suggests that dual diagnoses of mental illness and addiction stem from developmental changes in the amygdala. 

The amygdala, associated with fear, anxiety, and emotions, contributes to conditions. Dual diagnosis, frequently but challenging to treat, involves addictions to substances like nicotine, alcohol, and drugs, alongside mental illnesses such as anxiety disorders, depression, schizophrenia, and personality disorders. 

Lead author Dr. Andrew Chambers reports that at least half of those seeking help for addiction or mental health treatment have co-occurring disorders. Epidemiological data reveals that 20-50% of anxious or depressed individuals and 40-80% of those with schizophrenia, bipolar disorder, or antisocial personality also suffer from addiction.

Chambers’ team at Indiana University conducted a study comparing two groups of adult rats: one with surgically damaged amygdalas from infancy and a control group with intact amygdalas. Rats with damaged amygdalas exhibited abnormal responses to threats, greater sensitivity to cocaine after one exposure, and stronger behavioral changes with repeated cocaine injections, suggesting a hypersensitivity to addiction. The researchers concluded that the amygdala’s integrity influences both fear responses and drug sensitivity, independent of drug history.

Chambers proposes that a greater vulnerability to addiction, rather than the drugs’ ability to alter mental illness symptoms, explains the high rates of dual diagnosis. He also notes that dual-diagnosis patients respond less effectively to psychiatric medication, possibly due to underlying neural inflexibility. Chambers advocates for integrating mental health and addiction treatment, emphasizing that dual-diagnosis cases are prevalent because addiction and mental illness are neurobiologically linked.

Potential early harms to the amygdala include temporal lobe epilepsy, tumors, early brain injury, and complex interactions among genetic and environmental factors. Early emotional trauma paired with specific genetic backgrounds alters amygdala development, leading to dual-diagnosis disorders in adulthood.

What Are the Symptoms of Dual Diagnosis/Co-occurring Disorders?

The symptoms of dual diagnosis/co-occurring disorders are persistent sadness or hopelessness, irritability or anger, extreme mood swings, physical health issues, poor self-care, social isolation, withdrawal from social activities, increased conflicts, and strained relationships. The most common symptoms of dual diagnosis are given below as advanced by Brandon et al.’s study (2013), “Psychiatric Comorbidity and 12-Step Participation: A Longitudinal Investigation of Treated Young Adults”:

• Persistent Sadness or Hopelessness: Persistent sadness or hopelessness refers to a continuous state of feeling down or despairing without clear reason. This emotional state is a hallmark symptom of depression and impacts daily life and well-being.
  
• Irritability or Anger: Irritability or anger involves frequent episodes of frustration, annoyance, or rage. These emotions are disproportionate to the situation and strain relationships and disrupt daily functioning.
  
• Extreme Mood Swings: Extreme mood swings are severe and rapid changes in emotional state, ranging from intense highs to deep lows. These fluctuations interfere with personal and professional life, indicating a mood disorder.
  
• Withdrawal from Friends and Activities: Withdrawal from friends and activities is the process of distancing oneself from social interactions and previously enjoyed activities. This behavior is common in depression and other mental health conditions, leading to isolation.
  
• Difficulty Concentrating: Difficulty concentrating is the inability to focus on tasks or thoughts, leading to reduced productivity and impaired decision-making. This symptom is prevalent in various mental health disorders.
  
• Excessive Worry or Fear: Excessive worry or fear involves constant and overwhelming concerns about potential dangers or negative outcomes. These thoughts disrupt daily activities and are characteristic of anxiety disorders.
  
• Panic Attacks: Panic attacks are sudden, intense episodes of fear or discomfort accompanied by physical symptoms like heart palpitations, sweating, and shortness of breath. They are a key feature of panic disorder.
  
• Obsessive Thoughts or Compulsive Behaviors: Obsessive thoughts are repetitive, intrusive ideas, while compulsive behaviors are actions performed to relieve these thoughts. Together, they characterize obsessive-compulsive disorder (OCD).
  
• Avoidance of Certain Places or Situations: Avoidance of certain places or situations refers to deliberately steering clear of triggers that cause anxiety or fear. This behavior is associated with anxiety disorders, particularly phobias.
  
• Restlessness: Restlessness is a state of being unable to relax or sit still, accompanied by agitation or nervousness. This symptom appears in anxiety and attention disorders.
  
• Hallucinations: Hallucinations are sensory experiences that appear real but are created by the mind. These false perceptions, which involve any of the senses, are symptoms of severe mental health conditions like schizophrenia.
  
• Delusions: Delusions are strongly held false beliefs that persist despite evidence to the contrary. These irrational beliefs are commonly seen in psychotic disorders.
  
• Disorganized Thinking or Speech: Disorganized thinking or speech involves incoherent or illogical thoughts and communication, making it difficult to understand or follow conversations. This is a symptom of severe mental illnesses, such as schizophrenia.
  
• Paranoia: Paranoia is an irrational distrust of others, involving beliefs that others are out to harm or deceive. This symptom is seen in various psychiatric disorders.
  
• Unstable Self-Image: Unstable self-image refers to an inconsistent or distorted view of oneself, leading to difficulties in personal identity and self-worth. This is a key feature of borderline personality disorder.
  
• Intense, Unstable Relationships: Intense, unstable relationships are marked by extreme highs and lows, swinging between idealization and devaluation of others. This pattern is common in borderline personality disorder.
  
• Impulsive or Risky Behaviors: Impulsive or risky behaviors involve acting without thinking or engaging in dangerous activities without considering the consequences. This symptom is linked to substance abuse and personality disorders.
  
• Chronic Feelings of Emptiness: Chronic feelings of emptiness are pervasive sensations of being emotionally void or unfulfilled. This symptom is associated with various mental health conditions, particularly borderline personality disorder.
  
• Difficulty Managing Anger: Difficulty managing anger involves frequent outbursts or an inability to control aggressive impulses. This emotional dysregulation affects relationships and personal well-being.
  
• Using Larger Amounts or Over a Longer Period Than Intended: This phrase refers to the escalation of substance use beyond what was initially planned, indicating a loss of control and the development of substance dependence.
  
• Unsuccessful Efforts to Cut Down or Control Use: Unsuccessful efforts to cut down or control use signify repeated failed attempts to reduce or stop substance use, highlighting the addictive nature of the behavior.
  
• Spending a Lot of Time Obtaining, Using, or Recovering from Substance Use: This behavior involves dedicating time to acquiring, consuming, or recovering from substances, which interferes with daily responsibilities and activities.
  
• Craving or Strong Desire to Use Substances: Craving or strong desire to use substances refers to an intense urge or compulsion to consume a particular drug, driven by addiction.
  
• Failure to Fulfill Major Obligations Due to Substance Use: Failure to fulfill major obligations due to substance use describes neglecting responsibilities at work, school, or home because of the priority given to substance use.
  
• Continuing Substance Use Despite Social or Interpersonal Problems: This phrase highlights the persistence of substance use even when it causes or exacerbates conflicts in relationships, showing the overpowering nature of addiction.
  
• Giving Up or Reducing Important Activities Due to Substance Use: This behavior involves sacrificing hobbies, social interactions, or other activities in favor of substance use, indicating a deepening addiction.
  
• Using Substances in Physically Hazardous Situations: Using substances in physically hazardous situations refers to engaging in drug use in environments or situations that pose risks, such as driving under the influence.
  
• Needing More of the Substance to Achieve the Same Effect: Needing more of the substance to achieve the same effect describes the development of tolerance, where increased doses are required to feel the initial hit of the drug.
  
• Withdrawal Symptoms When Not Using the Substance: Withdrawal symptoms when not using the substance involve physical or psychological reactions that occur when drug use is reduced or stopped, indicating physical dependence.
  
• Exacerbation of Mental Health Symptoms Due to Substance Use: This phrase refers to the worsening of existing mental health conditions as a direct result of substance use, demonstrating the complex interplay between addiction and mental health.
  
• Frequent or Severe Episodes of Psychosis or Mania: Frequent or severe episodes of psychosis or mania involve recurrent or intense bouts of hallucinations, delusions, or hyperactive behavior, exacerbated by substance use.
  
• Using Substances to Cope with Mental Health Symptoms: Using substances to cope with mental health symptoms describes the self-medication behavior where individuals use drugs to alleviate the symptoms of mental health disorders.
  
• Increased Substance Use During Heightened Mental Health Symptoms: Increased substance use during heightened mental health symptoms refers to the escalation of drug consumption in response to worsening psychological conditions.
  
• Greater Difficulty Maintaining Employment, Relationships, and Responsibilities: This phrase highlights the challenges in sustaining work, personal connections, and obligations due to the impact of addiction and co-occurring disorders.
  
• Higher Hazard of Legal and Financial Problems: A bigger threat of legal and financial problems refers to the increased risk of encountering legal issues or financial instability due to substance use and related behaviors.
  
• Less Responsive to Traditional Treatments: Less responsive to traditional treatments indicates reduced effectiveness of conventional therapy approaches in individuals with dual diagnosis, necessitating specialized care.
  
• Higher Peril of Relapse: An elevated probability of relapse describes the increased chances of returning to substance use after a period of abstinence, particularly in the context of co-occurring disorders.
  
• Increased Risk of Physical Health Issues: Increased risk of physical health issues refers to the heightened vulnerability to chronic diseases and other health complications due to prolonged substance use and its effects on the body.
  
• Poor Self-Care: Poor self-care involves neglecting personal hygiene, nutrition, and overall well-being, as seen in individuals struggling with addiction and mental health disorders.
  
• Social Isolation: Social isolation describes the withdrawal from social interactions and community involvement, driven by the prioritization of substance use over relationships.
  
• Withdrawal from Social Activities: Withdrawal from social activities refers to the gradual cessation of participation in group events or social gatherings due to the impact of addiction.
  
• Increased Conflicts and Strained Relationships: Increased conflicts and strained relationships describe the growing tension and deteriorating connections with loved ones as a result of addiction-related behaviors.

What Are the Causes of Dual Diagnosis/Co-occurring Disorders?

The causes of dual diagnosis/co-occurring disorders are genetic factors, family history, genetic predispositions, brain chemistry imbalances in neurotransmitters, structural and functional brain abnormalities, and lack of access to integrated care. The most common causes of dual diagnosis are explained below as proffered by Torrens and Adan (2023) in their research “Recent Advances in Dual Disorders (Addiction and Other Mental Disorders)”:

• Genetic Factors: Genetic factors involve inherited traits that increase susceptibility to both mental health disorders and substance use. These genetic influences contribute to developing dual diagnosis.
  
• Family History: Family history refers to the presence of mental health disorders or substance use issues within a person’s family. This history increases the risk of developing similar conditions due to shared genetics and environmental factors.
  
• Genetic Predispositions: Genetic predispositions are inherited tendencies that make an individual more vulnerable to developing mental health disorders and substance addictions. These predispositions are passed down through generations.
  
• Brain Chemistry Imbalances in Neurotransmitters: Brain chemistry imbalances in neurotransmitters involve irregular levels of chemicals like dopamine and serotonin in the brain, which disrupt normal mood regulation and contribute to both mental health disorders and substance use.
  
• Structural and Functional Brain Abnormalities: Structural and functional brain abnormalities refer to physical or operational irregularities in the brain that affect behavior, mood, and decision-making. These abnormalities increase the risk of co-occurring disorders.
  
• Abnormal Brain Development: Abnormal brain development is the atypical growth or formation of the brain, leading to increased vulnerability to mental health issues and substance use disorders from an early age.
  
• Early Brain Injuries: Early brain injuries include physical damage to the brain during childhood or adolescence, which predispose individuals to dual diagnosis by affecting cognitive and emotional regulation.
  
• Exposure to Chronic Stress and Trauma: Exposure to chronic stress and trauma involves enduring prolonged or intense stressors and traumatic events, which contribute to the development of mental health disorders and substance dependence.
  
• Adverse Childhood Experiences: Adverse childhood experiences are traumatic events during childhood, such as abuse or neglect, that increase the risk of developing co-occurring mental health and substance use disorders later in life.
  
• Social Environment Factors: Social environment factors include influences like community, cultural norms, and societal expectations that impact mental health and substance use patterns, contributing to dual diagnosis.
  
• Poor Social Support: Poor social support refers to a lack of meaningful connections and assistance from others, which exacerbates mental health challenges and increases substance use as a coping mechanism.
  
• Socio-Economic Challenges: Socio-economic challenges involve financial instability, lack of education, and limited access to resources, which contribute to stress and the development of co-occurring disorders.
  
• Peer Pressure: Peer pressure involves the influence of friends or social groups encouraging substance use, which breeds addiction and exacerbates existing mental health issues.
  
• Coping Mechanisms: Coping mechanisms are strategies used to manage stress or emotional pain, such as substance use, which develops into addiction and worsens mental health disorders.
  
• Self-Medication: Self-medication is the use of substances to alleviate symptoms of mental health disorders, which precipitates addiction and further complicates mental health.
  
• Poor Emotional Regulation: Poor emotional regulation refers to the inability to manage and respond appropriately to emotional experiences, contributing to mental health disorders and substance abuse.
  
• Personality Traits Like Impulsivity and Risk-Taking: Personality traits like impulsivity and risk-taking involve a tendency to act without thinking and engage in dangerous behaviors, increasing the risk of substance use and mental health disorders.
  
• Bidirectional Influence Between Disorders: Bidirectional influence between disorders refers to the way mental health disorders and substance use disorders affect and exacerbate each other, creating a cycle of worsening symptoms.
  
• Neurobiological Changes Due to Substance Use: Neurobiological changes due to substance use involve alterations in brain structure and function caused by prolonged substance use, which exacerbate mental health disorders.
  
• The Stigma Surrounding Mental Health and Substance Use: The stigma surrounding mental health and substance use involves societal judgment and discrimination, which discourages individuals from seeking help and contributes to the development of co-occurring disorders.
  
• Lack of Access to Integrated Care: Lack of access to integrated care refers to the unavailability of comprehensive treatment that addresses both mental health and substance use disorders, leading to inadequate treatment and increased risk of dual diagnosis.

What Is the Treatment of Dual Diagnosis/Co-occurring Disorders?

The treatment for dual diagnosis includes integrated treatment programs, therapy, medication management, support groups, nutrition, and holistic approaches. Treatment for dual diagnosis is an integrated approach that addresses the mental health disorder and the substance use disorder simultaneously. The most common treatment methods for dual diagnosis are elaborated below as proposed by the National Institute on Drug Abuse (2024)’s “What does it mean to have substance use and co-occurring mental disorders?”:

• Integrated Treatment Programs: Integrated treatment programs are comprehensive plans that address both mental health and substance use disorders simultaneously. These programs merge therapeutic and medical interventions to create a unified approach to recovery, ensuring that all aspects of an individual’s condition are treated concurrently.
  
• Therapy: Therapy involves evidence-based approaches like cognitive-behavioral therapy (CBT) and dialectical behavior therapy (DBT) that focus on addressing the interconnected nature of mental health disorders and substance use. These therapies help individuals develop coping strategies, change harmful behaviors, and manage symptoms effectively.
  
• Medication Management: Medication management is the supervised use of medications such as antidepressants, antipsychotics, and treatments for substance use disorders (e.g., methadone, buprenorphine) to alleviate symptoms and support recovery. This approach ensures that both mental health and addiction issues are treated pharmacologically.
  
• Support Groups: Support groups are peer-led communities like Alcoholics Anonymous (AA), Narcotics Anonymous (NA), and Dual Recovery Anonymous (DRA) that offer mutual support and shared experiences for those with co-occurring disorders. These groups provide emotional support, accountability, and a sense of belonging.
  
• Case Management: Case management involves the coordination of care by professionals who connect individuals with resources, monitor progress, and ensure that all treatment components are effectively integrated. This service supports comprehensive recovery by addressing practical and logistical needs.
  
• Behavioral Therapies: Behavioral therapies are treatment modalities aimed at modifying negative behaviors and thought patterns related to both mental health and substance use. These therapies focus on developing healthier coping mechanisms and improving emotional regulation.
  
• Cognitive-Behavioral Therapy (CBT): Cognitive-behavioral therapy (CBT) is a structured approach that helps individuals recognize and change harmful thought patterns and behaviors associated with co-occurring disorders. CBT promotes the development of positive coping strategies and supports long-term recovery.
  
• Dialectical Behavior Therapy (DBT): Dialectical behavior therapy (DBT) is a therapy that teaches essential skills such as emotional regulation, distress tolerance, and interpersonal effectiveness. DBT is particularly useful in managing the emotional and relational challenges associated with dual diagnosis.
  
• Motivational Interviewing (MI): Motivational interviewing (MI) is a client-centered approach that enhances motivation to change by exploring and resolving ambivalence about treatment. MI empowers individuals to commit to recovery and make informed decisions about their health.
  
• Holistic Approaches: Holistic approaches are treatment methods that address the overall well-being of individuals with co-occurring disorders. These approaches integrate physical, emotional, and spiritual health to support comprehensive recovery.
  
• Nutrition and Exercise: Nutrition and exercise involve adopting a balanced diet and engaging in regular physical activity to improve physical health, boost mood, and reduce symptoms of mental health disorders. These practices contribute to overall recovery by enhancing energy levels and promoting well-being.
  
• Mindfulness and Meditation: Mindfulness and meditation are practices that involve focusing on the present moment and developing awareness of thoughts and feelings. These techniques help individuals manage stress, improve emotional regulation, and reduce the risk of relapse.
  
• Art and Music Therapy: Art and music therapy are creative therapeutic approaches that provide alternative ways for individuals to express emotions, process trauma, and develop coping skills. These therapies offer a non-verbal outlet for dealing with the challenges of dual diagnosis.

What Are the Challenges in Treating Dual Diagnosis/Co-occurring Disorders?

The challenges for treating dual diagnosis are diagnostic, stigma, and relapse risk. These challenges in treating co-occurring disorders require specialized care and attention. The most common challenges in treating dual diagnosis are explained below as evidenced by the National Institute on Drug Abuse (2024)’s “What does it mean to have substance use and co-occurring mental disorders?”:

• Diagnostic Challenges: Diagnostic challenges are difficulties in identifying dual diagnosis due to the overlapping nature of symptoms between mental health disorders and substance use. The complexity arises when mental health symptoms are confused with substance effects and vice versa. Accurate diagnosis requires comprehensive assessments by trained professionals who differentiate between the two conditions.
  
• Stigma: Stigma refers to the negative perceptions and discrimination faced by individuals with dual diagnoses from both mental health and addiction communities. This stigma leads to social isolation, hesitation to seek help, and inadequate treatment, further complicating recovery. Addressing stigma through education and advocacy is crucial for fostering understanding and improving access to care.
  
• Relapse Risk: Relapse risk is the increased likeliness of returning to substance use among individuals with dual diagnosis. Managing this risk involves implementing effective relapse prevention strategies, such as building a strong support network, engaging in ongoing therapy, and adhering to medication management. These measures are essential for maintaining long-term recovery and stability.

Are there financial assistance programs for dual diagnosis treatment?

Yes, there are financial assistance programs for dual diagnosis treatment. Wagener, Dan (2024), in the American Addiction Centers article, “Financing & Grants for Substance Abuse Treatment,” lists several forms of financial assistance for substance abuse treatment, which include: State-funded programs for substance abuse and detox treatment, grants from the Substance Abuse and Mental Health Services Administration (SAMHSA), coverage through Medicare and Medicaid, and support from the U.S. Department of Veterans Affairs, and benefits provided under the Affordable Care Act (ACA). SAMHSA (2020) awarded over $1 billion in grants to support substance abuse treatment and prevention programs. This funding enhances the capacity of treatment facilities and boosts access to care for individuals struggling with substance use disorders.

How do healthcare providers determine the appropriate treatment plan for dual diagnosis?

To determine the appropriate treatment plan for dual diagnosis, healthcare providers conduct comprehensive assessments that include medical history, mental health evaluations, substance use history, and social factors, as explained by VeryWell Mind staff writer, Gupta, Sanjana (2022) in  the article “What Is a Dual Diagnosis?” These assessments assist in developing personalized treatment plans that address the unique needs of each individual. Providers use standardized tools like the Structured Clinical Interview for DSM-5 (SCID-5) to diagnose mental health disorders. In a study by Shabani, Amir, et al. (2021, “Psychometric properties of Structured Clinical Interview for DSM‐5 Disorders‐Clinician Version (SCID‐5‐CV),” the SCID-5 demonstrated high inter-rater reliability (kappa = 0.85) for diagnosing mental disorders in individuals with substance use disorders.