The terms "developmental disability" and "mental retardation" are sometimes used interchangeably. In actuality, developmental disability is a broader classification, and mental retardation is one developmental disability that has multiple causes. Developmental disability refers to a wide variety of severe chronic conditions, originating before 18 years of age, due to mental and/or physical impairments, that interfere with an individual's ability to function in daily living at an effective level [1,2].

Intellectual disability is characterized by a significantly subaverage intellectual functioning that includes an intelligence quotient (IQ) below 75 on individually administered tests, onset before 22 years of age, and concurrent deficits in adaptive functioning in several areas [2]. A person's level of intellectual disability may be defined by their IQ or by the types and amount of support they need (adaptive functioning) [1,3]. The American Association on Intellectual and Developmental Disabilities (AAIDD) definition of intellectual disability focuses on adaptive skills and interactions between the person and his or her environment [2,4]. While the IQ test is a major tool in measuring intellectual functioning, other tests focus on limitations in adaptive behavior, which covers three types of skills [2]:

Providing care to those with DD is difficult due to a lack of awareness of healthcare needs and required tests and procedures. In a busy healthcare system, there is often not enough time spent explaining procedures, treatments, and care to patients. Allowing the individual to become familiar with personnel and equipment that will be used in patient care may be helpful in obtaining cooperation, but it is not always done because of time constraints. Scheduling appointments at a time when a family member or advocate can accompany the individual and be there to help communicate what is expected during a procedure is beneficial but also may not occur. Unfortunately, failure to take the time to establish rapport, explain procedures, and introduce a degree of comfort and safety to the patient may result in a partially finished procedure or test and unusable results. Time spent familiarizing the individual with healthcare providers and with the equipment may result in improved care for the individual with DD and satisfaction for the healthcare provider [5,7,15].

Difficulties in finding, keeping, and ensuring the competence of the direct support workforce in community developmental disability services is another challenge for individuals, families, providers, and policy makers. The recruitment and retention of competent direct support staff has been widely reported as one of the most significant barriers to the sustainability, growth, and quality of community services for people with DD [11,16].

Congenital heart conditions occur in about 50% of infants born with Down syndrome [25,26]. Screening by a pediatric cardiologist is essential, and surgical correction of defects is often necessary. Throughout their life span, individuals with Down syndrome should have follow-up care by a cardiologist [27]. Many individuals with Down syndrome will require subacute bacterial endocarditis prophylaxis with antibiotics prior to any invasive procedures or treatments, including routine dental care [25,28]. The American Heart Association recommendation states that antibiotic prophylaxis is not necessary for all individuals with certain heart conditions; the change in recommendation did not specifically address patients with DD [96]. The American Heart Association recommendations indicate that individuals with previous heart surgery should continue to take antibiotics before invasive procedures.

Atlantoaxial and atlanto-occipital instability are conditions that occur in about 10% to 20% of individuals with Down syndrome; however, actual spinal compression is rare [24,25,26,28]. Atlantoaxial instability is a term that refers to increased mobility and hyperflexibility of the cervical spine at the level of the first and second cervical vertebrae. Atlanto-occipital instability refers to a similar process in the occipital-cervical area [24]. Neurologic symptoms that may require surgical intervention can occur as a complication of this condition. Early onset of progressive arthritis of the spine is also common with aging and may manifest largely as a refusal to move [17,25,28]. A physical therapy evaluation may be helpful to suggest exercises that strengthen muscles and reduce trauma to the cervical spine. Cervical radiographic screening for atlantoaxial instability is no longer recommended routinely in adults, but cervical radiography in neutral, flexed, and extended positions should be considered if any of the signs or symptoms are present (Table 2) [28]. Pain management may become an issue as arthritis develops.

Assessing for seizures, administering medications appropriately, and managing the physical and psychologic aftermath of seizures are largely nursing responsibilities. Seizures may be difficult to recognize in patients with DD. In addition to generalized tonic-clonic movements, seizures may manifest as drop attacks, laughing spells, subtle tonic deviations of the eyes, or behavioral changes [38]. When one is familiar with an individual who has seizures, it is often possible to note signs that a seizure is imminent. Some individuals will have an aura or sign that they are about to have a seizure. Blurred vision, changes in light perception, or other sensory experience may cue the beginning of a seizure. If individuals can communicate this to those around them, support may be provided immediately. Even in individuals who cannot communicate clearly, it may be possible to recognize irritability or some other sign that may indicate a seizure is likely.

A number of urologic conditions may be associated with intellectual disability. For example, individuals with Down syndrome are at heightened risk for several problems, including obstruction in the lower urinary tract, renal hypoplasia, and ureterovesical junction obstruction [17,42]. Persons with Smith-Lemli-Opitz syndrome, a type of developmental disability, have been found to have upper urinary tract abnormalities at a rate of 57% and genital abnormalities at a rate of 71% [43]. Other problems that may occur in individuals with DD include renal hypoplasia, obstructive uropathy, and glomerular microcysts [44,97]. It should also be noted that, among boys and men with Down syndrome, undescended testicles are common and the risk for testicular cancer is increased [44].

Type 1 diabetes has been found to be more common among individuals with DD, particularly those with Down syndrome, than among the general population [98]. Other studies have found that individuals with DD who practice dietary management and regularly exercise have no higher incidence of type 2 diabetes than the general population [52,53]. This is a significant finding and appears to be in line with the general population's increase in diabetes along with an increase in obesity. Given that individuals with DD often tend to be shorter and stockier in build than the average person, it is particularly significant that a program emphasizing dietary controls and exercise may be helpful in reducing the incidence of diabetes among this population [17]. Although there are no specific recommendations regarding screening for diabetes in individuals with Down syndrome, it may be reasonable to screen these patients for this disease. They should also be counseled about diet, exercise, obesity, smoking, and alcohol use [28].

Lower bone density and resulting osteoporosis have been found to be common among people with DD [18,57,58,59]. A study of men institutionalized with DD found that 34% had ultrasound index values two standard deviations below an age-matched control group. Additionally, 51% had values more than two standard deviations below the reference group, demonstrating a very high occurrence of low bone mineral density [57]. A study of institutionalized postmenopausal women with DD found that 82% were at high risk for osteoporosis, with a severe decrease in bone mineral density [58]. This is due to multiple factors, including Down syndrome, smaller body size, endocrine abnormalities, reduced physical activity, reduced muscle strength, use of certain medications, and in women/girls, high phosphate levels [29,47,60].

Low vitamin D levels have also been reported in both men and women [60]. However, it is unclear if low vitamin D levels are associated with dietary issues or if they may result from other factors. Additionally, the effects of vitamin D on bone health have been difficult to separate from the associated effects of dietary calcium [61]. Certain anticonvulsant medications are known to affect the absorption of vitamin D, and this may also be a factor [62].

Individuals with mild-to-moderate developmental disabilities are likely to also have a diagnosis of mental illness. However, actual estimates of the frequency of occurrence of psychiatric diagnosis among those with DD vary [64,65]. Estimates of psychiatric diagnoses among individuals with intellectual disability range from 30% to 35% and suggest that some mental health conditions are more common among individuals with intellectual disability than in the general population [66,67,68]. There has been limited research studying mental health problems among adults with DD and even less in terms of treatment. There is little in the literature on assessment, diagnosis, and treatment of mental illness in this population; however, there is a growing interest in therapies that can help control challenging behaviors in the developmentally disabled population [67]. Accurate prevalence estimates are necessary to ensure the availability of appropriate treatment services [68]. Behavior problems are often assumed to be an outcome of the disability and not pursued beyond medicating to try to suppress behaviors [69,70].

A structured mental status assessment that includes all of the following areas will be most successful in collecting important data for psychiatric evaluation [70]:

Alzheimer disease is the most common form of dementia. Individuals with Down syndrome develop a clinical syndrome of dementia that is nearly identical to the characteristics of Alzheimer disease described in individuals without Down syndrome. The main difference is the early age of onset (i.e., late 40s or early 50s) in individuals with Down syndrome [17,74,75]. It is not clear why there is an increased likelihood of dementia in this population, but it is clear that the plaque and tangle formations found in the brain of individuals with Alzheimer-type dementia are sometimes found in the brains of individuals with developmental disorders. Additionally, there is an increase in frequency as the person with DD ages [74,75]. Epidemiologic and brain imaging studies of patients with Alzheimer disease and without Down syndrome have led to observations that patients with limited education or diminished baseline cognitive abilities may be at increased risk for Alzheimer disease. These data have led to the cognitive reserve hypothesis, which suggests that patients with better baseline cognitive abilities can tolerate more Alzheimer disease pathology and neuronal loss than patients with worse baseline cognitive abilities. Because most patients with Down syndrome have developmental disabilities and limited baseline cognitive ability, the cognitive reserve hypothesis would suggest that patients with Down syndrome are at increased risk of developing Alzheimer disease [75].

In some cases, the signs of dementia are associated with the use of neuroleptic medications, hypothyroidism, or depression. For a diagnosis of dementia to be made, the individual must be found to be functioning at a cognitive level below their baseline and the decline must be progressive. Nurses can make a significant contribution in helping to assess an individual for dementia because they are most likely to observe the individual frequently and be able to provide a clearer picture of changes from the baseline level of functioning. Additional studies of individuals with Down syndrome residing in communities have shown a lower occurrence of dementia than in previous studies of institutionalized populations. It is possible that the more active lifestyle of community residents has helped reduce their chances of having early onset dementia [74].

Psychotropic drugs may be of great benefit if they are given for specific diagnoses and symptoms. Drugs of most benefit in psychiatric care of individuals with DD are antidepressants, mood stabilizers, and antipsychotic medications [69]. Antidepressants are widely used in the general population, including in adolescents and children, for the treatment of depression, anxiety disorders, obsessive-compulsive disorders, and PTSD. Although the possibility of side effects is not entirely absent, consideration should be given to the damaging effects of untreated depression, and a balance should be achieved.

Mood stabilizers include lithium, valproic acid, lamotrigine, oxcarbazepine, and carbamazepine. With the exception of lithium, all of these drugs are also used for seizure control, and a dual benefit may be achieved in some individuals with DD [84]. These drugs are also used to treat bipolar disorder, and in individuals with DD who have a family history of bipolar disorder, it is appropriate to assess for signs of mood instability and treat accordingly [84]. Although there is limited data, clinical experience and some research indicate success in reducing aggression and self-injury in those with DD with the use of valproic acid [81].

Atypical (i.e., second-generation) antipsychotics were developed in the 1990s and are often used because they are thought to have fewer side effects and better efficacy than their predecessors [84]. They include risperidone, quetiapine, olanzapine, ziprasidone, aripiprazole, lurasidone, and paliperidone and are used to treat schizophrenia, severe anxiety, and aggression. These drugs are now more accepted than first-generation antipsychotics, but there is still a potential for extrapyramidal symptoms and weight gain [40,84]. It is important to note that the FDA has issued a Public Health Advisory for atypical antipsychotic medications because it has been determined that death rates are higher for elderly people with dementia when taking these medications. Antipsychotic medications are not FDA-approved for the treatment of behavioral disorders in patients with dementia [84].

Nursing responsibilities in the use of psychotropic medications are to provide accurate assessment information and monitor for side effects and interactions with other medications. Nurses should ensure that all direct care staff members are aware when a new medication is prescribed and advise them of what to watch for. All individuals receiving antipsychotics should be regularly tested for movement disorders to provide objective data [84]. Because seizure disorders occur so frequently in individuals with DD, nurses should be particularly alert for an advent of seizure or an increase in frequency when psychotropic medications are being used [40].

Behavior modification is based on the work of Skinner and is familiar to those who have taken a basic psychology course. The principle of behavior modification is based on the theory that all behavior is in response to positive and negative reinforcement and can be modified based on that theory. An outgrowth of Skinner's work was the establishment of behavior modification programs to treat the chronically mentally ill and individuals with DD [87]. In the 1950s, when these programs were put into place in institutional settings, considerable progress was made in the area of training institutionalized populations on basic skills. After a time, however, ethical and legal concerns arose about the use of negative reinforcement strategies, and many programs were abandoned [69]. However, there is still some value in the use of behavior modification, such as using a reward system to reinforce a desired behavior. For example, token economies, where the individual receives a token for a positive behavior and the token is later cashed in for a desired reward, have been successful in encouraging desired behaviors. If these interventions are included in a treatment plan and appropriate institutional approval is obtained, they can be very beneficial. The following is an example of the use of behavior modification to solve a health problem for a particular individual.

Cognitive therapy has been well-received in psychiatric care as an effective treatment for depression and anxiety. The principle of cognitive therapy is to help the individual change their negative self-view, thus improving his or her self-esteem and coping skills. Emphasis is placed on changing negative thinking patterns rather than just changing behavior [69,87]. Cognitive therapy focuses on learning new behaviors by using techniques introduced by the therapist [88,99]. Cognitive behavioral therapy has been used successfully with DD adults, and emerging studies, specifically on dialectical behavior therapy, have shown promise in effectively treating individuals with DD [67,69,88,100]. Role-playing, modeling, and homework assignments are some of the strategies used to initiate changes in thought and behavior.

Nursing has a major role in providing care for individuals with DD in all settings. Three important aspects of the nursing role are education, prevention, and support. Services are provided in care coordination, direct nursing care, health promotion, and health restoration. Nurses may also function in the role of case manager and be responsible for coordination of care provided by consultants and other members of the multidisciplinary team. In some settings, another provider will be the case manager and the nurse then has the responsibility of interpreting healthcare needs and educating other members of the team in those areas.

Local chapters of the AAIDD may serve as helpful resources for nurses who work with these families. The AAIDD includes professionals, family members, and advocates for individuals with DD. Its mission is to promote progressive policies, sound research, effective practices, and universal human rights for people with intellectual and developmental disabilities [2].

Advances in medicine, including improved health practices and medical care, have resulted in an increase in the number of DD individuals who survive into adulthood. As this population ages, additional needs must be met. These needs require a tailored approach from the nursing profession. The American Nurses Association (ANA) nursing standards provide specific direction on the scope of practice and a description of nursing of individuals with DD [94]. An important aspect of these standards is the emphasis on ethical principles in working with a dependent population. Society has a moral obligation to protect and provide for this group of people. Nurses are in a unique position to advocate for and protect these individuals.

Healthcare providers should work together with parents, other relatives, and guardians to make the best decisions regarding quality of life and health care. Generally, each individual will have someone appointed to either serve as a guardian or to act as an advocate in making decisions regarding health care. This will vary from state to state, and nurses should be familiar with the requirements in the state in which they practice. The ANA nursing standards can serve as a helpful resource [94].

There are a variety of state and federal laws that relate to institutional care provided for individuals with DD. Some are similar to regulations for nursing homes, but there is some variation. Nurses working exclusively with adults with DD should be aware of laws and regulations that apply to the group with which they are involved.