Psychiatric Co-morbidity


Medical Management Considerations


Resources for Families

Advisory Committee

Publication Information


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Persons with developmental disabilities are subject to the full range of psychiatric illnesses seen in the general population. All types of mental disorders can be observed among people with mental retardation or other developmental disabilities, with an incidence estimated to be at least two to three times that of the general population. In many cases, the initial psychiatric presentation will consist of a change in behavior or function. As many as 40% of people with mental retardation may experience a period of disturbed behavior and function at some time in their lives, which may signal the onset of a psychiatric disorder.

The treatment of behavioral and psychiatric disorders in persons with mental retardation and developmental disabilities is gaining increased recognition within the fields of primary care medicine and psychiatry. As a result, the primary care provider can take an active role in the assessment and treatment of these individuals. As the gatekeeper to additional consultation, the primary care physician should be capable of identifying and possibly treating medical illnesses, diagnosing and/or managing psychiatric disorders in collaboration with a psychiatric consultant, and working with the family and social service organizations to create an appropriate living environment.


Common psychiatric conditions noted in people with mental retardation and/or developmental disabilities include anxiety disorders, affective disorders (depression and bipolar disorder), obsessive compulsive disorder, thought disorders, personality disorders, and attention deficit hyperactivity disorder. Many of these conditions may first be manifest as a change in behavior. Common maladaptive behaviors include overactivity, sleep disorders, aggression, self-injurious behavior, and impulsiveness.

Prevalence of Psychiatric Co-morbidity Among Persons with Developmental Disabilities

  • 30-70%
  • Higher for adults than children
  • Depression and anxiety disorders most common


In the most simple terms, there are three major causes of severe, challenging behavior in people with mental retardation and developmental disabilities. These include medical conditions traditionally under the purview of primary and specialty care physicians, psychiatric disorders, and adaptive dysfunction (a mismatch between the needs, abilities, and goals of the individual within his or her environment). Psychiatric disorders and challenging behavior may also stem from the frustration and confusion persons with developmental disabilities often feel as a result of cognitive and physical limitations. In many cases, the etiology is of multiple origin with a medical or psychiatric disorder accompanied by some distortion in individual or family function.


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Because biological, psychological, and environmental factors all play a part in the origin of psychiatric disorders and challenging behavior, primary care physicians should seek to understand the causes of a patient’s behavior and evaluate potential medical, psychological, and environmental inputs into its origin.

The standard instrument for diagnosing psychiatric disorders in the general population is the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (Fourth edition) (DSM-IV). This instrument has significant shortcomings in understanding the behavior of people with mental retardation and other developmental disabilities. Many of these concerns are addressed through the use of modified or alternative criteria, discussed below.

Physical Examination

A thorough medical assessment by the primary care physician is the first step in the process of diagnosing and managing a psychiatric disorder or challenging behavior. The physical examination and laboratory testing are important to rule out the presence of a treatable medical condition. Occult medical illnesses, in various organ systems, have been reported to cause psychiatric symptoms in up to 10% of cases in the general population, and may contribute to psychiatric symptoms in up to 50% of patients. This phenomenon may be more frequent in people with mental retardation because they have greater health care needs compared to people of the same age and sex in the general population. The most commonly involved organ systems (and medical conditions) include:

  • The nervous system (epilepsy);
  • Metabolic disorders (thyroid disease);
  • Infections (pneumonia, otitis media, dental infections, sinusitis);
  • Gastrointestinal disorders (gastroesophageal reflux);
  • Cardiac anomalies (arrythmias); and
  • Orthopedic problems (arthritis).

In addition, medication side effects are commonly associated with behavioral change and should be considered. In most cases, the epidemiology of chronic health problems mimics the pattern associated with aging in the general population (congenital problems in the young, degenerative processes in the elderly). However, the risk of specific health conditions may be increased as a result of specific genetic syndromes. The nature of these risks can be better assessed following a genetic consultation.

If the primary care physician overlooks a medical or organic cause of behavioral problems (e.g., hypothyroidism in a person with Down syndrome), it is unlikely to be recognized by the consulting psychiatrist or other care provider. Laboratory testing should be based upon clinical suspicions aroused by the history and physical examination. Even when these produce no clues, however, the clinician should remain ever vigilant and open to the possibility of an occult medical problem.

Behavioral Observations (signs and symptoms)

Behavioral problems associated with psychiatric conditions in people with mental retardation include aggression, self-injury, overactivity, and sleep disturbances. In addition, rumination, elopement, property destruction, and other behaviors are occasionally seen. Changes in behavior should be thoroughly worked up and not just dismissed as a part of mental retardation.

Behavioral Questionnaires

Inventories or behavioral scales are available to facilitate the evaluation of behavioral problems in children and adults with mental retardation. These include The Reiss Scale for Maladaptive Behavior, The Psychopathology Instrument for Mentally Retarded Adults (PIMRA), and The Aberrant Behavior Checklist. It is frequently of benefit to use two or more inventories and to have more than one care provider complete the instrument.

Diagnostic Hypotheses

It is important for the clinician to formulate a psychiatric diagnosis or etiologic hypothesis before prescribing a treatment. For example, in a person with epilepsy who is treated with phenobarbital and is noted to be overactive, the presence of vegetative signs should alert the clinician to the possibility of depression or mania. The clinician might then consider changing the anticonvulsant medication to carbamazepine, which can have a mood-stabilizing effect.

Strict diagnostic criteria for psychiatric disorders may not be met due to a number of features related to mental retardation, including cognitive and communicative deficits. (Return to the index for a document on Nonverbal Patients.) Frequently, a clear diagnosis cannot be made and the clinician may resort to empirical trial-and-error treatments. People with developmental disabilities who present with emotional or behavioral problems that do not constitute a specific psychiatric disorder may still benefit from psychiatric and behavioral treatment approaches. For example, antidepressants may help for irritability, self-injurious behavior, and overactivity.

It should be noted that automatically equating unusual behavior with psychosis will lead to overdiagnosis of psychosis and underrecognition of anxiety and depression. In addition, some symptoms may be unusual but usually are not the result of psychosis, such as imaginary friends; speaking in altered voices; experiencing the presence of dead or absent others; and phenomena the patient can start or stop at will.


Treatment is often based upon a combination of psychopharmacolgy, behavior modification, psychotherapy/counseling, cognitive therapy, and social skills training. These approaches are likely to require collaboration between the primary care provider and an interdisciplinary team of providers and caregivers in gathering data, evaluating the success of treatment, and modifying the treatment plan. A significant portion of treatment may require referral to a psychiatrist and/or psychologist, especially for those primary care physicians who see very few patients with developmental disabilities and/or do not feel comfortable managing psychiatric disorders or challenging behavior. Psychiatrists with expertise and interest in caring for persons with developmental disabilities would be ideal, although access to such individuals may be limited.

Because environmental, psychological, and biological factors all play a part in the successful treatment of psychiatric disorders and challenging behavior, the treatment of behavioral problems in persons with mental retardation and/or developmental disabilities may require changes in caregiver environment, psychoactive medications, and medical interventions, or any combination of the three.

The needs of an individual with both a developmental disability and mental illness are still often overshadowed by the primary diagnosis of a disability and/or mental retardation. Diagnostic overshadowing refers to the way some clinicians may attribute behavioral or psychiatric problems to patients’ cognitive delays. It is important for physicians to focus on treating psychiatric disorders in addition to managing the developmental disability.

Environmental Causes

Adaptive dysfunction relates to a mismatch between the needs, abilities, and goals of the individual within his or her environment. The environment may include the school, place of employment, home, and/or family unit. If a patient is poorly matched to his or her surroundings, their behavior may serve to control or alter the social environment.

The cause or purpose of behavioral dysfunction is amenable to an analysis of the patient’s goals and the current environment to identify areas of conflict. In particular, the potential communicative nature of the behavior is considered. For example, does an outburst always accompany a request to accomplish difficult tasks? Behavioral problems may be reduced or eliminated when the person is taught appropriate, replacement behaviors that serve the same function. This intervention is called functional analysis and is best conducted as part of a comprehensive diagnostic process, which includes traditional medical and psychiatric evaluations. Environmental dysfunction can often be distinguished from mental illness or an organic cause by a lack of vegetative signs (weight loss or sleep problem) and a relationship between the behavior and antecedent events.

Psychoactive Medications

Given the vast number of psychoactive medications on the market, it is wise for primary care physicians to be familiar with one or two drugs in each of the major classes of medications. This is generally sufficient to allow the clinician the flexibility to make appropriate choices between treatments. Ideally, psychiatric consultation is available to help determine appropriate initiation and dosage parameters for these medications. Clinicians should be comfortable using:

  • Antiepileptic medications (carbazepine, valproate);
  • Antimanic medications (lithium carbonate, valproate);
  • Tricyclic antidepressants (desipramine, imipramine);
  • Stimulants (methylphenidate, dexadrine);
  • Antianxiety medications (buspirone, hydroxyzine);
  • Anti-aggression medications (propanolol, nadolol);
  • Anti-self-injurious behavior medications (naltrexone);
  • Serotonin reuptake inhibiting antidepressants (sertraline, fluoxetine);
  • Neuroleptics; and
  • Atypical neuroleptics (risperidone, olanzapine).

Many of the medications identified above have multiple effects. Carbamazepine is an effective anticonvulsant with antidepressant, antimanic, and neuralgic effects. It is an excellent first choice in the treatment of aggression and/or self-injurious behavior, particularly in the presence of overactivity or a sleep disorder. The neuroleptics are often a good first choice of treatment during an acute problem, but every effort should be made to find alternative treatments because of long-term side effects. In addition to treating depression, antidepressants are valuable in the treatment of anxiety disorders and attention deficit hyperactivity disorder.

Supporting Families

The level of family stress and the families’ ability to utilize the resources of the extended family or obtain alternative community supports are important predictors of outcome. For example, a recent study of children with epilepsy noted that family function was one of the most important predictors of behavioral problems. Similar findings have been noted in families of children with cerebral palsy, cystic fibrosis, and other chronic illnesses. The primary care provider should always remember that a strong family is a more effective treatment partner.


Interventions for people with developmental disabilities and behavioral problems should be accompanied by careful follow-up. The behavioral response to the treatment plan should receive careful scrutiny. People taking psychoactive medication may require periodic screening for drug levels, side effects, and behavioral changes depending upon the medication used. In addition, the diagnosis may need to be reconsidered in light of the response to treatment. For example, when a trial of stimulant medication causes a worsening of behavior or ever-increasing doses are required to maintain therapeutic effect, the diagnosis of bipolar disorder should be considered.

The following is a simple summary of steps to follow in diagnosis and treatment of a psychiatric disorder:

  • Rule out the presence of a medical disorder;
  • Evaluate the presence of environmental supports and stressors;
  • Look for a complex of behavioral symptoms;
  • Establish a psychiatric diagnosis using standard or modified criteria;
  • Develop treatment goals;
  • Monitor treatment with a predetermined methodology; and
  • Establish a treatment endpoint.

Appendix 1: Medical conditions that may cause psychiatric symptoms

  • Epilepsy/seizures
  • Speech and language disorders
  • Thyroid dysfunction
  • Central nervous system damage
  • Dental pain
  • Gastrointestinal disorders
  • Urinary tract infections
  • Sinus/ear infections
  • Hypoxia
  • Hypercarbia
  • Hypoglycemia
  • Electrolyte disturbances
  • Psychoactive medication use or withdrawal
  • Hepatic or renal disease
  • Thiamine deficiency
  • Systemic infection
  • Post-operative state
  • Tourette’s Syndrome
  • Chronic arthritis
  • B vitamin deficiency
  • Porphyria
  • Lupus (SLE)
  • Wilson Disease


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Peer-Reviewed Journal Articles

Dykens, E.M., Hodapp, R.M, (1997). Treatment Issues in Genetic Mental Retardation Syndromes. Professional Psychology, Research and Practice, 28(3), 263-270.

Fuller, C.G., Sabatino, D.A. (1998). Diagnosis and Treatment Considerations with Comorbid Developmentally Disabled Populations. Journal of Clinical Psychology, 54(1), 1-10.

Kastner, T., Walsh, K. (1999). Challenging Behavior Problems in Children with Mental Retardation. In: Developmental and Behavioral Pediatrics. (Eds.) Parker and Zuckerman. Little Brown.

Masi, G. (1998). Psychiatric Illness in Mentally Retarded Adolescents: Clinical Features. Adolescence 33(130), 425-434.

Ryan, R., Sunada, K. (1997). Medical Evaluation of Persons With Mental Retardation Referred for Psychiatric Assessment. General Hospital Psychiatry 19, 274-280.

Silka, Van R. Hauser, M.J. (1997). Psychiatric Assessment of the Person With Mental Retardation. Psychiatric Annals 27, 3.

Special Interest Groups/Other Publications

Ludwig, B. (1997). Mental Health Supports for People with Developmental Disabilities.

National Information Center for Children and Youth with Disabilities. (1998). Emotional Disturbance fact sheet. Retrieved on June 13, 2006 from

International Consensus Handbook on Psychotropic Medication and Developmental Disabilities(1998). Reiss, S., Aman, D.(Eds.) Nisonger Center. Columbus Ohio.

Rubin, I.L., Crocker, A.C. (1989). Developmental Disabilities: Delivery of Medical Care for Children and Adults. Philadelphia: Lea & Febiger, pp. 334-366.

Ryan, R. (1996). Handbook of Mental Health Care for Persons with Developmental Disabilities. Chapter 4.

Ryan, R.M et al. (1997). Nonverbal Complaints/ Clues (handout from Whole Person Assessment Seminar) (June).

Smith Consultant Group and McGowan Consultants. (1998). (Ed.) M.L. Snyder, Signs and Symptoms of Illness. Health and Wellness Reference Guide. (pp. 117-121.) Neri Productions, State of Tennessee Commission on Compliance.

Wardinsky, T. (1998). Training Manual on Medial Needs of Individuals with Developmental Disabilities. Alta California Regional Center, 1997-1998 Wellness Project.


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American Academy of Child and Adolescent Psychiatry, 800-333-7636,

The Arc, 800-433-5255,


California Department of Developmental Services, 916-654-1690,

California Regional Centers, 915-654-1958,

Exceptional Parent Magazine, 800-247-8080,

March of Dimes Birth Defects Foundation, 914-428-7100,

National Alliance for the Mentally Ill, 800-950-NAMI,

National Association for Dual Diagnosis, 800-331-5362,

National Mental Health Association, 800-433-5959,


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Theodore A. Kastner, M.D., M.S.

Felice Weber Parisi, M.D., M.P.H.

Robin L. Hansen, M.D.

Terrance D. Wardinsky, M.D.


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Funded by a grant from the California Department of Developmental Services

For more information, contact:

Center for Health Improvement

1330 21st Street, Suite 100

Sacramento, CA 95814

(916) 901-9645

This document does not provide advice regarding medical diagnosis or treatment for any individual case, and any opinions or statements contained in this document are not intended to serve as a standard of medical care. Physicians are encouraged to view the considerations presented in this document in light of evolving scientific information. This document is not intended for use by the layperson. Reproduction of this document may be done with proper credit given to California Department of Developmental Services and the Center for Health Improvement.