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NIDCD Workshop on Epidemiology of Communication Disorders

March 29-30, 2005
Bethesda, Maryland

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The Epidemiology of Communication Disorders Workshop was held March 29-30, 2005, in Bethesda, Maryland. The purpose was to review current epidemiologic knowledge in the field of communication disorders and to suggest ways to encourage more epidemiologic research. Findings from earlier epidemiologic investigations and reports on useful biostatistical methods were presented. Howard Hoffman, Program Director for Epidemiology and Biostatistics, Division of Scientific Programs, NIDCD, chaired the workshop. The Agenda and list of invited participants is attached.

The workshop convened at 8:30 a.m. when James Battey, Jr., M.D., Ph.D., Director, NIDCD welcomed the attendees and gave the charge for the meeting. Karen Cruickshanks, Ph.D., University of Wisconsin, presented the keynote address on the importance of population-based research studies for understanding the burden of communication disorders in society. She explained the critical role that epidemiologic research plays in the design and evaluation of interventions that may prevent or delay impairment and disability. Following the keynote address, Paul Eggers, Ph.D., NIDDK, and Teri Manolio, Ph.D., NHLBI, summarized epidemiologic research programs in their Institutes. Mary Ann Guadagno, Ph.D., CRC, then provided an overview of the operation of NIH epidemiology study sections and what is critical for success in epidemiologic research applications.

The primary focus of the workshop was on how to stimulate more epidemiologic research in NIDCD mission areas.  Workshop participants reviewed clinical and epidemiologic knowledge within each of the NIDCD mission areas in presentations to the whole group. Then, as members of panels within their field of expertise, they were asked to recommend priority topics where more epidemiologic research would be useful. Participants were also asked to offer advice on infrastructure needs (e.g., the issuance of Program Announcements) that could stimulate more epidemiologic research on communication disorders.

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Introduction to Epidemiologic Research

Epidemiologic research may not be familiar to some research investigators. The etymology of the word epidemiology is instructive: “epi” means either “on or about”, “demos” is the “people or population”, and “logy” means “the study of”. Abraham Lilienfeld (1920-84), Professor of Epidemiology at Johns Hopkins University, defined epidemiology “as the study of the distribution of a disease or physiological condition in human populations and of factors that influence this distribution”. Another often-quoted definition of epidemiology is: “the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control of health problems” (Last JM, A Dictionary of Epidemiology, IEA, 1988). This rewording of the definition clarifies the purpose of epidemiologic research, which is to provide knowledge to improve health and prevent disease. Dr. Lilienfeld also pointed out also noted the distinction between descriptive and analytic epidemiology. Descriptive epidemiology examines rates (often using demographic variables) to determine whether there is uniformity by person, time, and place. Non-uniformity of rates can lead to the identification of high risk groups for targeted interventions or the generation of hypotheses.

Analytic epidemiology assesses hypotheses of association between suspected risk factors and health outcomes. Analytic epidemiology, in which hypothesis-based examination of large data bases is done, can be facilitated through the assembly and maintenance of data bases. Such studies make good use of scarce data that are costly to collect. The statistical techniques for assessment of associations in analytic epidemiology can be applied equally to: 1) experimental studies using populations or groups of individuals as units in clinical trials, and 2) observational studies that use individuals as the unit for analysis in (prospective) cohort, case-control, or cross-sectional study designs.

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Priorities for Epidemiologic Research in Hearing

Scope of epidemiologic investigation in hearing

Few classic epidemiologic studies of the sort designed to document disease prevalence and identify risk factors have been conducted in the area of hearing. Modern epidemiology, which encompasses analytical studies, clinical trials, outcomes research, and health services delivery, has received scant attention in the field of hearing research.

Reviewers of epidemiologic research grant applications are encouraged to recognize the need for research in quality-of-life areas, which encompasses the majority of the NIDCD portfolio. The classic association of epidemiology with hard endpoints (such as death) should be expanded to include soft endpoints that deal with sensory deficits in the areas, for example, of hearing, balance, taste, and smell.

Epidemiology training

Based on the report that only 1.1% of NIDCD funded grants are associated with epidemiology, there is a definite need to increase the number of investigators with training in epidemiology and an interest in hearing research. Training options include MPH, MS, or PhD degrees in epidemiology for clinicians and audiologists, post-doctoral training for those in related disciplines, and pilot grant mechanisms to perform feasibility studies and collect preliminary data for epidemiology applications. Currently, R21s are available for exploratory work, to develop tests and questionnaires, and bring communities together for large population-based cohort studies. The need for investigators trained in epidemiology was endorsed by the other panels and occupied much of the discussion. Some impediments to this approach are the realities of designing epidemiologic studies and getting them funded. Specific funding amounts are not currently allocated to mission areas or types of research; rather, funding is determined by the priority scores for all grants assigned to NIDCD, with some projects identified for special consideration based on unfunded areas, priority populations, and other Institute programmatic factors. Clinicians and audiologists may not see any benefit in epidemiologic training because the chances of getting a project funded on the first application are low, lack of success is discouraging, and financial pressures to earn clinical income for self-support compete with time needed to revise and resubmit an unsuccessful grant. Workshops at epidemiology meetings and elsewhere may encourage epidemiologists to seek collaborations with those with clinical expertise. Program Announcements, Requests for Applications (RFAs) for grants and Requests of Proposals (RFPs) for contracts are mechanisms that can be used to raise the success level of hearing-related epidemiological applications.

Priorities for epidemiologic research in children

Hearing

When universal newborn hearing screening (UNHS) was recommended by an NIH consensus conference in 1993, controversy arose over the efficiency and cost effectiveness of this approach. Now that UNHS is widespread within the United States, population-based studies to evaluate impact on both short-term and long-term outcomes are needed. For example, there is a need to document and evaluate both false positive and the false negative rates associated with UNHS programs in order to reduce costs and minimize the negative impact of hearing loss on quality of life. Other profitable research areas include: incidence data and associated long-term outcomes (e.g., speech and language development, academic achievement, quality of life, economic success) by etiology, incidence of multiple disabilities for children with hearing loss, incidence of progressive and late onset hearing loss, and a comparison of outcomes for children who are implanted versus those who wear hearing aids. Early predictors for long-term success for children with hearing loss should also be identified.

Otitis media

In 2004, the American Academy of Pediatrics, the American Academy of Family Practice, and the American Academy of Otolaryngology Head and Neck Surgery jointly issued evidence-based guidelines for diagnosis, treatment and management of acute otitis media (AOM) and otitis media with effusion (OME) in children 2 months to 12 years of age. The only strong OME recommendation issued was to use pneumatic otoscopy as the primary diagnostic method, and to distinguish AOM from OME to guide effective management. The guidelines for AOM included a strong recommendation to assess pain and recommend treatment to reduce pain. Several other recommendations relating to diagnosis, treatment, management, and prevention of these conditions were issued by both panels. Perhaps most importantly, the AOM panel recommended a change in current treatment to permit observation for 48 to 72 hours without antibiotics in children 6 months to 2 years old with nonsevere illness and an uncertain diagnosis and in children 2 years and older with nonsevere illness. The observation period without use of antibacterial agents is for children with AOM without high fever (< 39ºC or

Given these new otitis media guidelines, it will be extremely important to use epidemiologic research methods to determine how the guidelines affect clinical practice and whether their adoption leads to any significant changes in otitis media outcomes. Of particular interest in light of the option for observation without antibiotics is monitoring of the incidence of serious AOM sequelae (e.g., mastoiditis and intracranial complications). Also, since the recommended period of observation or “watchful waiting” is accompanied by instructions to seek further medical help if symptoms persist or worsen, it will be important that studies examine the compliance with these instructions in addition to monitoring serious AOM sequelae.

Prevention of AOM remains an important challenge. Prevnar®, a vaccine containing the 7 most common serotypes involved in invasive pneumococcal disease, was efficacious in preventing AOM in randomized controlled trials. However, the effect was quite small – 6% for a single episode and about 20% for recurrent AOM and treatment with tympanostomy tubes for recurrent AOM and chronic OME. Population-based studies of the effect of Prevnar® on AOM would be welcome, since its effectiveness in preventing AOM in the community setting may differ from that observed in the trials because of its potential effects on colonization and serotype replacement.

In addition to vaccination, prevention of AOM with xylitol, a naturally-occurring sugar alcohol used widely as low-calorie sweetener in foods, should be explored. Two randomized controlled trials in Finland demonstrated that xylitol reduced the rate of AOM by 30-40% in children in a daycare setting. However, the trial used 5 daily doses, which is impractical and a regimen not likely to be practical for widespread use. Evaluation of xylitol efficacy in a trial with a more practical dosing regimen is needed.

Since daycare attendance is the most often identified and the strongest modifiable risk factor for AOM, prevention strategies that evaluate changes in use of daycare (e.g., later entry, fewer children) or infection control practices within the daycare setting should be developed and tested.

Priorities for epidemiologic research in adults

Hearing

Age-related hearing loss (ARHL) is common in older adults; the population-based Beaver Dam cohort study identified a HL (PTA >25 dB) incidence of 21% over a 5 year period in adults ≥ 48 years, and more than half of those with ARHL at the initial exam had progressive HL at the 5-year follow-up. Prospective epidemiologic studies designed to identify etiologic factors, including those that are modifiable, are needed. Studies employing quality of life measures should be conducted to assess the impact of ARHL in the at-risk adult population. Intervention studies are needed to determine efficacy of hearing protection devices and drugs and pharmacologic rescue in noisy work and leisure environments. More studies to determine prevalence, incidence and risk factors for hearing loss in minority populations are also needed. The advances being made in the genetics of hearing loss should be used in large-scale genetic epidemiology studies of hearing loss. Development of phenotypic definitions of age-related hearing loss and subtypes is vital for population genetic studies.

Other conditions

Epidemiologic studies designed to determine prevalence and incidence rates of tinnitus and identify etiologic factors for this condition are needed. Data emerging from these studies could be used to design prevention strategies for this condition.

Ancillary studies

Large population-based studies offer an opportunity to include questions and tests to evaluate the burden of hearing loss, tinnitus and otitis media. One example is to include hearing assessments in prevention studies of cardiovascular disease based on the intriguing initial associations of cardiovascular risk factors with hearing loss in adults. Inclusion of new assessments in existing studies has advantages (less expensive, time efficient because the study population does not have to be recruited) and disadvantages (questions are not worded optimally, often must compromise on a less sensitive/specific exam or test based on respondent burden). Nevertheless, adding ancillary projects to well-designed existing studies can be a cost-effective way to collect useful initial data.

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Priorities for Balance and Vestibular Epidemiologic Research

The balance and vestibular field lags significantly behind other NIDCD components in epidemiological research. In order to move forward, epidemiologically significant common language to describe vestibular symptoms needs to be developed. In particular, the distinction between vertigo, disequilibrium, and presyncope is often lost in standard American Medical Association Current Procedural Terminology (CPT® ) code based population epidemiology, yet it is critical for understanding symptoms as they may relate to organ systems and disease processes in the population setting. Therefore, standardized definitions are necessary to share and compare data between studies, and validation work needs to be completed with these definitions.

With suitable definitions in mind, the development of validated survey tools, including well defined questions and simple and definitive clinical tests, to acquire true incidence and prevalence data of balance disorders is needed. Research in the epidemiology of balance problems should ideally involve experts across multiple specialties, particularly otolaryngology and head and neck surgery, neurology, cardiology, internal medicine, family medicine, geriatrics, and physical therapy. Developing a written manual to illustrate performing screening vestibular tests is a possible method to integrate meaningful balance epidemiology into ongoing larger epidemiology studies.

Because balance disorders are multidisciplinary, it seems that an ideal initial mechanism for determining the incidence and prevalence of balance disorders, as well as their associated co-morbidities, is to integrate these questions with larger epidemiologic studies where much of the data will be collected on co-morbid conditions. From the perspective of the NIDCD in particular, which is interested in the vestibular system, developing screening methodology that distinguishes vestibular disorders from more global balance disturbances would be valuable.

Another problem is the lack of standardization in vestibular and balance testing that exists among major vestibular balance testing centers. Such standardization will be required to compare data across studies. With standardized tests, the necessary longitudinal data on tests of vestibular function can be developed. Currently, only limited age-related data exist and these data are not specific to the normal aging process, but also include subjects with significant age-related morbidities. Such information is needed to inform patients about changes in ability and disability with increasing age, to develop effective interventions, and to decrease related morbidity and mortality. Because of the paucity of epidemiologists involved in balance research, it is necessary that we develop collaborations with epidemiology in other fields, particularly aging and neuroepidemiology.

Because falls are the major morbidity commonly related to balance problems, development of tools to discern the mechanisms of falls in different age groups would be useful in understanding this public health problem. Although there is a significant body of research on falls in the older population, there are few studies on falls or imbalance in younger populations and there are no epidemiology studies that include vestibular dysfunction. The NIDCD should attempt to foster evidence based medicine to evaluate outcomes on well defined populations of balance disordered patients in order to better understand the etiologies, injuries related to falls, and to develop preventive intervention strategies.

The field also needs to develop vestibular and balance related quality of life instruments that are sensitive to change in order to assess improvement, if any, after patients are treated for vestibular and balance disorders.

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Priorities for Chemosensory (Smell and Taste) Epidemiologic Research

The chemosensory area of NIDCD primarily funds basic science, with significant advances in mechanisms of sensory function and research in olfactory and taste genes. Clinical research arose from centers that characterized causes, signs and symptoms of chemosensory disorders, originally estimated by an expert panel to afflict 1% of the population. Findings from these centers and related research include: 1) olfactory dysfunction results from damage to olfactory receptors and nerves by pathogens, nasal/sinus disease, and head trauma, 2) olfactory dysfunction is an early marker for neurodegenerative disorders (e.g., Alzheimer’s Disease [AD], Parkinson’s Disease [PD]) and schizophrenia), 3) retronasal olfactory impairment occurs with compromised oral health and mouth movements, 4) ageusia is rare and spatial taste loss is more common, and 5) phantom taste, smell, touch and oral pain syndromes result from damage to sensory nerves and structures.

Aging is associated with decreasing sense of smell, loss of spatial taste function, and relative stability in whole mouth taste function but probable losses of bitter taste perception. Less is known about those losses associated with aging alone and those associated with disease. Diminished quality of life has been described by those with multiple chemosensory problems, those with abrupt onset and/or that reach a noticeable level. These include: disruption of life with constant chemosensory sensation; impaired role functioning with occupations requiring adequate chemosensation (e.g., chef/food provider, firefighter); fear of failing to smell warning odors (e.g., fires, natural gas); loss of emotion connected with olfaction; changes in food enjoyment, dietary selection and weight; suffering from disorders that are not observable, that are relatively unknown, and for which little treatment is available.

Treatments from chemosensory disorders have been limited to those for: 1) nasal or sinus disease inflammation or viral damage (e.g., tetracycline, steroids, surgery) and 2) phantom sensations (e.g., benzodiazepines, surgery).

Funding for clinical research has been low, in part due to lack of apparent treatments. However, clinical and epidemiological research in chemosensation is needed to increase understanding of the extent of disorders, risks for these disorders, changes with aging, and how chemosensory disorders influence health and quality of life. There is also a need to define normal and usual variation in chemosensory functioning and how this variation associates with diet and lifestyle behaviors (e.g., intake of vegetables, smoking, and alcohol use) and thus risk of chronic diseases such as cardiovascular disease, cancer, and obesity.

There is a need to understand how chemosensory function serves as markers for chronic conditions (e.g., AD, PD) and if early identification promotes positive outcomes of these conditions. It is also important to know how chemosensory function associates with the management of chronic conditions (e.g., obesity). It is necessary to identify treatments that improve chemosensation and quality of life, while being cost effective. At all levels, coordination is needed across basic, clinical and epidemiological research approaches.

Defining the disorder and normal variation

There are challenges to conducting population-based chemosensory research. One is how to “operationalize” the disorders with tests that have consensus approval. Previous research shows that reports of disorders of che­mosensory functioning show poor correlation with measured dysfunction, unless that loss is gross (e.g., anosmia). Little is known if reported acute functioning (e.g., super tasting, olfactory acuity) associates with high performance on testing (although olfactory losses are described in those with olfactory hypersensitivities). Needed are tests of smell (orthonasal, retronasal), taste (whole mouth, spatial) and somatosensory (touch, temperature, pain) functioning that are portable, adminis­tered consistently with ease, cost efficiently, and minimally taxing to participants (e.g., cognitive ability, time).

Work among experts (in psychophysics, practice, research, and epidemiology) could lead to the selection of optimal methods, weighing the advantages and disadvantages of each method. Thresholds provide comparison across chemosensory disorders but may not reflect perception of more intense sensations. Perceived intensity offers more information if it is collected with valid measures and methods that avoid sensory fatigue. Identification tasks indicate dysfunction but do not differentiate those who live in “pastel” versus “vibrant” olfactory or taste worlds. Hedonic measures present minimal cognitive challenge but lack specificity to stimulus quality or intensity. Electrophysical (e.g., olfactory event-related potentials) and biological measures (fungiform papillae density, sniff volume) may complement direct behavioral measures without cognitive demand if they can be done efficiently and cost-effectively. Genotyping shows promise if there is increased understanding of how the gene relates to sensory response (e.g., TAS2R38 and bitterness of phenylthiocarbamide [PTC], 6-n-propylthiouracil [PROP]). While genotyping captures what is present at birth, it may not reflect chemosensory sensations at the time of testing. As well, interesting parallels exist across communication disorders and brain derived neurotrophic factors, which are important for the development of taste and olfactory receptor organs.

Population-based studies with chemosensory disorders

These studies would provide accurate data on the prevalence of chemosensory disorders, co-morbidities (e.g., neurodegenerative disorders and olfactory dysfunction), who is at risk, and what are the risks (or compromises on quality of life). These studies could provide insight into preventing chemosensory disorders, for example, environments, health practices, and prevention efforts that promote nasal/sinus health and minimize chemosensory disorders. Longitudinal studies or cross-sequential designs could differentiate chemosensory changes from primary versus secondary aging and assess relationships between chemosensory disorders and degenerative disorders (e.g., olfactory dysfunction and neurodegenerative disorder severity; does one precede or predict the other). Adding dietary and quality of life measures to these studies would determine how these disorders may be related to dietary and other lifestyle practices (poor dietary quality, weight changes) and how quality of life may be impacted.

Incorporating chemosensory testing into ongoing and continuing population studies would increase the probability that advances in these areas will be achieved. A model is the inclusion of olfactory and taste testing into the Beaver Dam, Wisconsin Offspring Study (BOSS) and plans to include chemosensory testing in the National Health and Nutrition Examination Survey (NHANES).

Another fruitful area appears to be the linking of chemosensory functioning with otitis media. Pathogens that cause these infections damage taste from the chorda tympani nerve and this damage can influence whole mouth taste, somatosensory and retro-nasal olfactory sensations. Preliminary evidence suggests these oral sensory changes map onto differences in food behaviors (e.g., preference, intake) and adiposity in children and adults. Taste may provide an early functional measure of middle ear insult that precedes more chronic infections associated with otitis media with effusion (OME) and hearing problems. Conversely, a history of chronic OME may be associated with taste dysfunction later in life. Important questions include how oral sensory function correlates with reported exposure to pathogens and other exposures (e.g., prescription drugs). Case-controlled studies could identify if dietary, lifestyle, and health outcomes differ statistically between those with (case) and without (control) significant history of otitis media, especially when there is a dose-response relationship with outcome measures.

Controlled clinical trials must test emerging treatments of chemosensory disorders, including those to treat phantom sensations and olfactory dysfunction related to nasal/sinus disease. These trials aim to define medical, quality of life, and cost-effectiveness outcomes and promote evidence-based clinical practice.

Researching variation in chemosensory function

Chemosensory function varies across individuals as shown by evidence from animals and humans using behavioral, psychophysical, anatomical and emerging gene markers. The variation is influenced by genetics, environment (e.g., hormones, exposure to pathogens, medications) and interactions between the two across the lifespan. For example, emerging gene research in taste shows that humans have an unusually high level of functional diversity in bitter taste receptor genes. Since chemosensation functions as a gatekeeper for ingestive behavior, a key question is how markers of chemosensory variation associate with sensation and hedonics of simple and complex stimuli (e.g., foods and beverages), patterns of intake, and diet-related chronic diseases (obesity, cardiovascular disease and cancer).

Population-based studies are needed on the epidemiology of variation in chemo-sensory function including groups that vary in ancestry, environment, and age (young, middle-aged, elderly). Including measures of chemosensory variation into existing population-based studies would be an efficient and effective way to address this need (e.g., Beaver Dam, NHANES, population-based studies of cardiovascular risk, child development studies). These population-based studies can serve to test the impact of chemosensory variation on dietary behaviors, lifestyle behaviors (e.g., alcohol use, smoking), chronic disease risk and quality of life. Ideally, these studies would be coordinated across countries to obtain a global perspective on the epidemiology of chemosensory variation. Knowledge of the impact of chemosensory variation on health behaviors could help to improve public health efforts to decrease the risk of chronic diseases. Chemosensory variation could affect the response to health promotion programs involving changing diet and lifestyle behaviors. Epidemiologic studies could assess whether outcomes from health promotion programs differ with chemosensory variation. Findings from these studies could guide development of health promotion programs that can be tailored to the individual.

A summary overview of examples of chemosensory interfaces with epidemiological studies is provided below in Table 1.

Table 1. Epidemiological studies (from lowest to highest scientific evidence) and chemosensory (smell and taste) conditions and disorders

Case series — what clinicians see

Increase identification of chemosensory disorders; develop standard assessment measures and tests; increase health professionals who can assess and identify chemosensory disorders; increase use of standard testing and surveys

Ecological study — geographical comparisons

Coordinated studies across diverse populations in the United States and other countries, including possible migration studies to test environmental and genetic factors that influence risk of chemosensory disorders and variation in chemosensory functioning

Cross sectional study — survey, snapshot in time

Include standardized chemosensory testing in nutrition and health surveillance studies such as the United States National Health and Nutrition Examination Survey (NHANES)

Case-control study — compare people with and without a disease

Compare cases and controls for difference in chemosensory functioning, especially in communication-related disorders (e.g., otitis media) and other chronic conditions (e.g., cancer, cardiovascular disease, obesity)

Cohort study — follow people over time to study diseases

Include chemosensory testing into existing or emerging studies and emerging or on-going trials

Randomized controlled trial (RCT)

Chemosensory response to treatments and how chemosensory functioning influences response to health interventions

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Epidemiologic Research Priorities in Voice, Swallowing, Speech, and Language

The voice, speech, and language panel expanded its scope slightly to include issues of swallowing as well. In the following text, “communication” will be used to refer collectively to these domains.

Five themes were identified. The first and most prominent was that of examining issues of communication over the lifespan. The second was that of studying exposures and their effects on individual differences in communication, particularly with those levels or aspects of communication viewed as constituting disability or as compromising quality of life. A third topic was that of the association of individual differences in communication and communication disorders with important life outcomes. In this latter case, these outcomes could provide better information on aspects of disability. Fourth was the need for measurement development. Fifth there is a need to look for ways to initiate epidemiological studies that are feasible and thus efficient suggesting a screening battery/inventory that might be used across epidemiological studies.

Lifespan perspective of communication problems

The focal point of discussions concerned important population-based studies that could yield a wide range of important information on multiple aspects of communication. These studies were organized according to a lifespan perspective in order to address particular issues at salient developmental time periods. These studies are summarized in Table 2.

Table 2. Lifespan perspectives on epidemiologic research problems in voice, swallowing, speech and language

Age Group

Type of Study

Research Areas

Birth through preschool (perinatal to 4+ years)

Cohort studies

  • Perinatal-post natal risk factors (exposed +/-)
    • Infection
    • Assisted reproductive technology (ART)
    • Unique exposures (e.g., Romanian adoptees)
    • Congenital disorders, including problems of voice/swallowing
  • Course of communication development
    • Late talker
    • Autism
    • Regressions and new cases
    • Stuttering and voice problems

Pre and early adolescence (9 to 14+ years)

Cross-sectional studies

  • Voice and fluency at pubescence
  • Social systems and communication functions
    • Quality of life
    • Social participation
    • Stigma, teasing

Early adulthood (18 to 25+ years) through middle age (35 to 54 years)

Cross-sectional studies

  • Criminal behaviors
  • Communication functions
    • Occupational performance
    • Income
    • Social participation
    • Quality of life
    • Chronic illness and other conditions
    • Menopause

Mature and older adults (55+ years)

Cross-sectional and cohort studies

  • Communication system integrity
  • Communication function
  • Social systems and communication functions
    • Quality of life
    • Social participation

Birth through the preschool years

Cohort studies that involve exposed and unexposed infants and parents are needed. Longitudinal studies of exposed infants could be used to explore current issues regarding obstetrical and neonatal practice patterns (maternal infections, assistive reproductive technologies), early rearing or nutrition (Romanian adoptees, breastfed infants, or vitamin-deficient mothers), or selected congenital disorders. Population studies could focus on the course of communication development with a particular focus on the emergence of communication disorders (autism, stuttering, or voice problems) and, as well, the occurrence of regressions in development that may lead to “new cases”.

Pre and early adolescence

This is a time of important biological and social changes. Each of these changes may have impact on communication (voice changes, social systems changes). In this respect, studies of the roles of communication on quality of life, social participation, and such events as stigma and teasing are important.

Early adulthood through middle age

In early adulthood there are important transitions to new activities and social roles. This is a time when a subgroup of individuals enters into antisocial/criminal activities and suggestions have been made that communication disorders are associated with this. Better data and theory are needed for understanding this association and whether communication may be causal or coincident with such social problems.

The specific occupational demands placed on communication are not well known, although it is likely that changing workforce demographics are resulting in more jobs that require communication skills and fewer jobs that place less demand on these skills. If this is true, the economic impact of communication disorders on the U.S. workforce will be substantial. It is not clear how these changes are affecting those who enter the workforce with limited communication skills.

In young to middle-aged adults, the emergence of chronic illnesses and other conditions may also adversely affect communication skills.

Post-menopausal women are understudied and suggestions have been made that the biologic changes occurring during this period may contribute to both voice and swallowing problems.

Mature and older adults

First, the basic integrity of communication systems needs to be documented in mature and older adults, and this information needs to be associated with competence in basic but important communication functions and the impact of these competencies on quality of life and social participation. In most of these areas, issues concerning voice, swallowing, speech, and language can be addressed. It is important to design studies that emphasize the reciprocal relationships between diagnosis of a communication disorder and its association with limitations that could result in disability. Data that allow the demonstration of morbidity associated with individual differences is also needed.

Early identification of individuals with dementia and other health care problems that are not part of normal aging could lead to earlier intervention and prevention of subsequent morbidity, which could lead to the preservation of a quality of life at a higher functioning level than otherwise. All of these aspects have direct implications for expenditure of health care dollars, and the costs of communication disorders to individuals and society.

Development of measures

Two areas of need related to measurement development were identified. First, assessment standards are needed. Second, measures of communication that are suitable for use in population studies are also needed. These could be questionnaires, or brief observations that are developmentally appropriate for different groups and for different aspects of communication. This could be accomplished by means of consensus conferences or via funding grants (e.g., R21s). Also necessary are measures developed to study communication functions, quality of life, social participation, and occupational function. Most of the measures that exist in these areas are not well adapted to communication or communication disorders or are not suitable for larger, population-based research studies. The group thought it was necessary to develop tools and determine the epidemiology of communication problems across the lifespan before legitimate studies of epidemiology of treatment could be completed.

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Cross-Cutting Issues

Archive data bases

Several data bases from prior cohort studies could be used to generate important data. A system of identifying these and making them known to the research community would be a very cost effective way of increasing the amount of research on epidemiology of communication disorders. The development of repositories of existing data that could be made available to the research community would be useful, as would ensuring that there are funding mechanisms available for secondary analyses of existing data.

Future aspirations

Given the prominence of epidemiological research outside the United States, improved opportunities for international collaboration would be useful. Finally, population-based research could be increased if the advantages of epidemiological principles and study designs were better known in the clinical research community.

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