Mental Retardation

Definition

Mental retardation is a developmental disability in which a person has intellectual functioning that is significantly below average; usually defined as an intelligence quotient (IQ) of 70 or below. Mental retardation includes disabilities in various skills and possible behavioral issues.

Description

Mental retardation is the most common developmental disorder. The term “retarded” is sometimes viewed as derogatory; the terms mentally handicapped, mentally disabled, or mentally challenged are often used instead. Mental retardation is caused by a brain defect that is either genetic (inherited) or occurs during early development—before, at, or shortly after birth. This disorder is usually diagnosed during early childhood and almost always by the age of 18. Older adults with mental retardation have typically had this condition all of their lives. Mental retardation due to certain genetic disordersmay not appear ormaynot be recognized until adulthood. In cases where intellectual deficits are minimal, mental retardation may not be diagnosed until behavioral symptoms appear in later life.

The most common cause of mental retardation is Down syndrome. Most people with Down syndrome have mild to moderate retardation, but some are severely retarded. The majority of American adults with Down syndrome are employed and live in group homes or other independent living arrangements and some are married.

Fragile X syndrome is a common inherited cause of mental retardation in males and also a significant cause in females. Autism, a disorder characterized by social and communication difficulties, is common in people with fragile X syndrome and other types of mental retardation. About 25% of people with autism have some degree of mental retardation.

Approximately two-thirds of people with cerebral palsy (a neurological disorder that affects muscle coordination and body movement) have some degree of mental retardation. The most severe form of cerebral palsy, spastic quadriplegia/quadriparesis, is often associated with moderate to severe retardation. People with cerebral palsy who also have epilepsy or an abnormal electroencephalogram have increased risk for mental retardation.

About 30% of children born with spina bifida (incomplete development of the spinal cord or its covering) have mild to severe mental retardation.

Older adults with mental retardation have many of the same concerns as older people in the general population. In addition, older adults with mental disabilities generally have lower incomes, fewer opportunities to make choices for themselves, and less knowledge of options. Many mentally retarded adults are unemployed, underemployed, or in day or sheltered programs with little or no pay and no pensions.

Special health concerns

The rates of and risk factors for age-related health conditions are similar for people with mental retardation and the general population. Approximately 50% of people born with Down syndrome have congenital heart defects; however, the majority of these defects can be surgically corrected during childhood. Individuals with Down syndrome are 15–20 times more likely to develop leukemia, with most cases occurring in the first few years of life.

People with mental retardation often show signs of aging earlier than the general population and are more prone to dementia. It is estimated that at least 25% of people with Down syndrome over the age of 35 develop signs and symptoms of Alzheimer's-type dementia. Many people with Down syndrome experience functional decline due to treatable health problems such as hypothyroidism, depression , or hearing or vision loss. These conditions may co-exist with Alzheimer's disease or be mistaken for symptoms of dementia.

Obesity is a common problem for the mentally disabled, particularly among women and those with Down syndrome. Between 1985 and 2000 the percentage of mentally disabled adults with obesity increased from 19.4% to 36.4%, whereas the percentage in the general population increased from 11.4% to 20.6%. Obesity puts these individuals at risk for:

• high blood pressure (hypertension)
• heart disease
• type 2 diabetes
• arthritis
• respiratory disease

Mentally retarded adults may have less access to primary healthcare, cancer screening, dental care, and other needs than the general population. They may have difficulties communicating their symptoms and concerns, cooperating during screenings and diagnostic tests, and participating in rehabilitation. These difficulties can be compounded by mental health disorders, symptoms of dementia, or other physical conditions.

Women's health concerns

Women with Down syndrome are likely to experience adaptive, sensory, and/or rational thinking losses at an earlier age than the general population. Some studies suggest that women with Down syndrome enter menopause at an earlier age. Women with mental retardation may be at higher risk for osteoporosis and related bone fractures due to:

• amenorrhea—the absence of menstrual periods
• earlier menopause
• inactivity
• increased likelihood of falling
• need for certain medications such as anticonvulsants, excessive thyroid medications, and steroids

Older women with mental disabilities are often less educated, in worse health, and more dependent on government services than other people with disabilities. Mentally retarded women are also less likely to receive regular screenings for breast, cervical, ovarian, and uterine cancers and are less likely to recognize and report warning signs of cancer and other disorders.

Demographics

Down syndrome occurs in 1 out of every 733 live births and there are more than 350,000 Americans with this condition. It affects people of both genders and all races and socioeconomic groups. Fragile X syndrome affects about 1 in 4,000 males and 1 in 8,000 females of all racial and ethnic groups. The symptoms are usually more severe in males than in females.

The number of older people with Down syndrome and other forms of mental retardation is increasing. An estimated 500,000 Americans over age 60 are mentally retarded. This number is expected to double by 2030.

Causes and symptoms

Causes of mental retardation

Mental retardation can be caused by disease, a brain abnormality, or injury that occurs during fetal development, birth, or childhood. In many instances the cause of the mental retardation is not known. Known causes of mental retardation are:

• Down syndrome—the presence of part or all of an extra chromosome 21
• fetal alcohol syndrome
• fragile X syndrome—a mutation in a gene on the X chromosome
• spina bifida
• chromosomal abnormalities such as cri du chat and Prader-Willi syndromes
• Niemann-Pick disease—a group of inherited defects in lipid metabolism that cause brain damage with varying degrees of mental retardation
• congenital hypothyroidism—the thyroid gland does not produce enough thyroid hormones
• birth defects in the brain such as hydrocephalus or cortical atrophy
• infections such as congenital cytomegalovirus
• toxoplasmosis—a disease caused by a parasite found in cat feces and undercooked meat
• rubella or German measles—nearly 90% of infants whose mothers contracted rubella during the first trimester of pregnancy are mentally retarded

Mental retardation can be caused during or soon after birth by:

• asphyxia or lack of oxygen
• neonatal hypothyroidism—inadequate production of thyroid hormones by the thyroid gland in newborns
• kernicterus—a neurological condition caused by severe jaundice
• certain inherited metabolic disorders including phenylketonuria (PKU) and galactosemia

Older children can become mentally retarded due to:

• head injury
• physical abuse such as shaken-baby syndrome
• stroke
• extreme malnutrition l exposure to poisons such as lead or mercury
• infections such as meningitis and pertussis (whooping cough)

Before the development of a vaccine against Haemophilus influenza type b (Hib), Hib meningitis caused mental retardation in one out of three infected children.

Medical conditions of mentally retarded seniors

About 50% of mentally retarded people cannot care for themselves. A similar percentage has a physical disability or problems with mobility. About 25% have no useful speech and approximately 10% lack basic comprehension and are completely dependent on others.

Approximately two-thirds of mentally retarded individuals living at home have long-term medical conditions or major physical disabilities. As they age, adults with mental retardation tend to develop more medical problems than other people of the same age. The more severe the retardation, the more medical problems are likely to occur. However, as many as half of the medical problems may go undiagnosed.

Psychiatric disorders are about five times more commonin adults with mental retardation than in other adults of the same age. Autistic traits appear in about 50% of older people with mental disability. Approximately 75% of the mentally disabled aged 65 and older have a major psychiatric disorder such as depression, bipolar disorder , schizophrenia, or dementia.

Dementia is associated with Down syndrome in older adults, but not necessarily with other forms of mental retardation. Older adults with Down syndrome are also at an increased risk for Alzheimer's disease. It is believed that the genes that increase risk of Alzheimer's disease are located on chromosome 21, which is partially or completely duplicated in Down syndrome. The incidence of Alzheimer's disease in people with Down syndrome is estimated to be 5–10 times higher than in the general population and symptoms may appear as early as age 30. By age 40 almost all adults with Down syndrome develop at least some characteristics of early-onset Alzheimer's and nearly half have symptoms of Alzheimer's after age 50. Seizures are also very common after age 50. Early menopause appears to be a risk factor for early dementia among women with Down syndrome. About 75% of people with Down syndrome develop symptoms of dementia before the age of 70. Almost all older adults with Down syndrome have brain conditions indicative of Alzheimer's disease, they do not necessarily exhibit symptoms of dementia.

Common symptoms of dementia among people with Down syndrome include:

• lack of adaptability
• socially inappropriate behavior
• apathy
• depression
• increased agitation or aggressive behavior

Older mentally retarded adults can develop severe behavioral problems. Because of their limited coping skills, older mentally retarded adults may find it difficult to adjust to changes in their home or work situations. Transitions such as moving to a new environment or losing a familiar companion can cause behavioral problems including:

• social withdrawal
• continuous repetition of a specific behavior
• self-injury
• aggression

Diagnosis

Mental retardation is usually diagnosed in childhood. Physical examinations, laboratory tests, and sophisticated neurological tests can diagnose the cause of mental retardation in almost 50% of cases. Identifying the cause of the retardation may help with diagnosis of medical problems since certain conditions are associated with different types of retardation.

Diagnosis of medical conditions in persons with mental retardation is the same as for the general population, but it can be much more difficult, particularly when patients have low verbal skills and cannot express their thoughts and feelings. As a result, medical conditions often go undetected in people with mental retardation. In addition, illnesses and medical conditions may present atypical clinical symptoms in the mentally retarded. Prompt diagnosis and treatment of medical and mental disorders in people with mental retardation increases their life expectancy.

Health care providers must phrase their questions carefully so as to be understandable, and commonly used psychiatric evaluation tools may not be appropriate. Information about medical history and symptoms from family members, caregivers, and other professionals, in addition to behavioral and functional assessments can be crucial for diagnosis. Chronic pain or mental illness is sometimes diagnosed by behavioral changes such as withdrawal, apathy, or lack of responsiveness. Agitation, aggression, or sleeplessness may be symptoms of delusions or hallucinations.

It is recommended that people with Down syndrome receive a baseline test for dementia at age 30 and be screened annually thereafter for cognitive deterioration.

Treatment

Treatment of physical and mental disorders in older adults with mental retardation is similar to that in the general population, although mental limitations may complicate treatment. Psychiatric problems may be treated with drugs and behavioral therapy. Patients who are mentally disabled are at an increased risk for side effects of antipsychotic medications. Side effects may include movement problems, and tardive dyskinesia or involuntary movements, particularly of the facial muscles. Studies have shown that risperidone is well-tolerated in patients with mental retardation and provides sustained improvement in disruptive behaviors. Ziprasidone has also been shown to reduce the frequency of maladaptive behaviors and improve weight in the mentally retarded.

Prognosis

In 1930 the average lifespan of a person with mental retardation was 20 years, by 1980 it was 60 years. The average life expectancy of older adults with mental retardation has since increased to 66 years and continues to lengthen, with women living somewhat longer than men. Up to 80% of people with Down syndrome now live to age 55.

The problems experienced by people with mental disabilities tend to increase with age due to mental decline and loss of mobility. With proper support, these older adults can remain in their homes.

Common causes of death among people with mental retardation are:

• heart disease
• respiratory disease
• cancer
• dementia

Prevention

Several forms of mental retardation originate during pregnancy and can be avoided. The most preventable cause of mental retardation is fetal alcohol syndrome, which is caused by the mother consuming alcohol during pregnancy. Folic acid , a B vitamin, taken during pregnancy helps protect against spina bifida and other spinal cord defects that cause mental retardation. Rubella, pertussis, and Hib infections can be prevented with vaccines. Most newborns are tested for PKU. The effects of PKU and galactosemia, including mental retardation, can be prevented by a strict diet initiated shortly after birth. Hypothyroidism can be successfully treated if it is detected early. Early diagnosis and treatment of jaundice can help prevent kernicterus, a disorder caused by the presence of bile in the brain and spinal cord. Neural-tube defects, chromosome abnormalities, and gene mutations that cause mental retardation may be screened for prior to birth and people with family histories of inherited disorders may receive genetic screening and counseling.

QUESTIONS TO ASK YOUR DOCTOR

Caregivers or family members may want to ask a physician the following questions about people with mental retardation.

• Will the patient age differently than people in the general population?
• If the patient has Down syndrome are they more likely to have dementia?
• How is dementia diagnosed?
• What are special challenges confronting the patient?
• What type of therapies will benefit the patient?
• What is the best living situation for the patient?
• What arrangements should be made for the patient as their caregivers age?

As with the general population, diet, exercise , other lifestyle factors, and access to quality healthcare greatly affect the health and well-being of older adults with mental disabilities. Studies have shown that exercise improves physical fitness, psychological health, sociability, and life satisfaction, and decreases depression in older people with Down syndrome.

Caregiver concerns

Seniors with mental retardation may not know about bodily changes associated with aging or recognize warning signs of disease. It is important for caregivers to:

• watch for behavioral changes that may indicate an underlying medical problem, especially in patients with poor communication skills
• provide access to health information and to healthcare professionals who are experienced in treating the mentally disabled
• provide necessary support for medical examinations, tests, and treatment
• be alert for any potential mistreatment of the person in their care

About 75% of mentally disabled adults live at home and are cared for by family members. In the United States, more than 25% of these caregivers are estimated to be over 60 years of age. With increasing age these family members may no longer be able to provide adequate care or cope with behavioral problems. For the first time in history the vast majority of people with mental disabilities are expected to outlive their caregivers. In addition, an increasing number of older adults with mental disabilities are being moved out of institutions and into the community. As this population grows there is an increased need for support services, regardless of whether the individuals are living in their own homes, with their families, or in other residential situations.

KEY TERMS

Alzheimer's disease —A degenerative brain disease that is the most common form of dementia.

autism —A spectrum of developmental disorders characterized by impaired social and communication skills and certain behavioral patterns.

cerebral palsy —A disability caused by brain damage before, during, or shortly after birth that is characterized by poor muscular coordination and speech difficulties.

cognitive —Refers to intellectual activities including thinking, reasoning, and remembering.

Dementia —A usually progressive mental deterioration.

Down syndrome —Also called trisomy 21; a congenital condition characterized by an extra partial or complete chromosome 21, mental retardation, and specific physical attributes.

fetal alcohol syndrome —A wide range of birth defects, including mental retardation, in children whose mothers consumed large amounts of alcohol during pregnancy.

fragile X syndrome —An inherited disorder caused by repeated sequences on the X chromosome resulting in mental retardation and other abnormalities in males, but few if any problems in females who have a normal second X chromosome.

hypothyroidism —A deficiency in hormone production in the thyroid gland.

intelligence quotient (IQ) —A number used to express a person's relative intelligence based on a standardized test.

maladaptive —An inability or poor ability to adjust to change.

phenylketonuria (PKU) —An inherited metabolic disorder caused by an enzyme deficiency that results in the accumulation of the amino acid phenylalanine and its metabolites in the blood.

spina bifida —A neural-tube defect in which the spinal column does not completely enclose and protect the spinal cord.

Older family caregivers of aging mentally disabled adults need to plan for the future. Important considerations are:

• respite services to provide the caregiver with time off
• future living arrangements
• financial planning l guardianship

Resources

BOOKS

Davidson, P. W., et al. Mental Health, Intellectual Disabilities and the Aging Process. Oxford, UK: Blackwell, 2003.

Marks, B. A., et al. Exercise and Nutrition Health Education Curriculum for Adults with Developmental Disabilities, 3rd ed. Chicago: University of Illinois, 2006.

PERIODICALS

Fisher, Kathleen, and Paul Kettl. “Aging with Mental Retardation: Increasing Population of Older Adults with MR Require Health Interventions and Prevention Strategies.” Geriatrics 60, no. 4 (April 2005): 26–9.

Seltzer, Martha, T. Heller, and M. W. Krauss. “Special Issue on Aging.” American Journal on Mental Retardation 109, no. 2 (March 2004).

OTHER

“Caring for Someone with Developmental Disabilities.” National Family Caregiver Support Program Resources. November 1, 2004. [cited April 13, 2008]. U.S. Department of Health and Human Services Administration on Aging. http://www.aoa.gov/press/nfc_month/2004/fact_sheets/Fact%20Sheet%20-%20Careing%20for%20someone%20with%20DD.pdf

“Elder Health at Your Fingertips: Ch. 37: Mental Retardation.” Aging in the Know. May 31, 2005 [cited April 13, 2008]. American Geriatrics Society. http://www.healthinaging.org/agingintheknow/chapters_ch_trial.asp?ch=37

“Fact Sheet: Aging: Older Adults and Their Aging Caregivers.” American Association on Intellectual and Developmental Disabilities. March 23, 2005 [cited April 13, 2008]. http://www.aamr.org/Policies/faq_aging.shtml

Lott, Ira. “Alzheimer's Disease and Down Syndrome.” National Down Syndrome Society. 2002 [cited April 13, 2008]. http://www.ndss.org/index.php?option=com_docman&task=doc_view&gid=112

ORGANIZATIONS

American Association on Intellectual and Developmental Disabilities, 444 North Capitol Street, NW, Suite 846, Washington, DC, 20001-1512, (800) 424-3688, (202) 387-2193, http://www.aamr.org.

American Geriatrics Society, Foundation for Health in Aging, The Empire State Building, 350 Fifth Avenue, Suite 801, New York, NY, 10118, (212) 755-6810, (800) 563-4916, (212) 832-8646, [email protected], http://www.healthinaging.org.

American Psychiatric Association, 1000 Wilson Boulevard, Suite 1825, Arlington, VA, 22209-3901, (703) 907-7300, [email protected], http://www.psych.org.

The Arc of the United States, 1010 Wayne Avenue, Suite 650, Silver Spring, MD, 20910, (301) 565-3842, (800) 433-5255, (301) 565-3843/(301) 565-5342, [email protected], http://thearc.org.

National Down Syndrome Society, 666 Broadway, New York, NY, 10012, (800) 221-4602, (212) 979-2873, [email protected], http://www.ndss.org.

Rehabilitation Research and Training Center on Aging with Developmental Disabilities, Department of Disability and Human Development, College of Applied Health Sciences, University of Illinois at Chicago, 1640 W. Roosevelt Road, Suite 436 IIDD, MC 626, Chicago, IL, 60608, (312) 413-1647, (312) 413-1630, http://www.uic.edu/orgs/rrtcamr.

Margaret Alic Ph.D.