Progressively Lowered Stress Threshold (PLST) Psychoeducation Intervention
Kathleen C. Buckwalter, PhD, RN, FAAN
The progressively lowered stress threshold (PLST) model developed by Hall and Buckwalter (1987) provides the foundation for a psychoeducation intervention to assist formal and informal caregivers in understanding behaviors and planning care for persons with dementia (PWD). To achieve this purpose the model addresses three dimensions of a dementing illness and the interaction of these dimensions across the disease process. The three dimensions include: 1) losses associated with cognitive decline and their accompanying symptom clusters, 2) behavioral states, and 3) stage of the disease process.
Losses accompanying cognitive decline are clustered into four groups a) intellectual losses, b) affective or personality losses, c) conative or planning losses, and d) a progressively lowered stress threshold. The model focuses on the fourth cluster by postulating that progressive cerebral pathology (as seen is PWD) is accompanied by a progressive decline in the stress threshold. A reduced tolerance to stress is reflected in the altered proportion of behavioral states. As the stress threshold declines over the course of the disease, there is a progressive reduction in normative behaviors and an increase in anxious and dysfunction behaviors (e.g., agitation). [Insert Figure1]
An important assumption of the PLST model is that all behavior has meaning, therefore, all stress-related behavior has an underlying cause (Hall & Buckwalter, 1987). The model identifies the following six factors that contribute to stress in PWD: a) physical stressors (e.g. pain, discomfort, infection, b) misleading stimuli or inappropriate stimuli, c) change of environment, caregiver, or routine; d) internal or external demand that exceed functional capacity; e) fatigue; and f) affective response to perceptions of loss (Hall & Buckwalter, 1987; Hall, Gerdner, Zwyart-Stauffacher, & Buckwalter, 1995).
Assessment of the temporal patterning of agitation over a 24-hour period reveals that PWD usually experience relatively few stressors in the early morning hours. However, as stressors accumulate, the person begins exhibiting anxious behaviors such as loss of eye contact and increased psychomotor activity (e.g., restlessness). Without intervention, stressors continue to accumulate until the stress threshold is exceeded, usually by mid-afternoon, resulting in severe agitation characterized by cognitive and social inaccessibility (Hall & Buckwalter, 1987). The patient cycles between states of anxiety and severe agitation if the stress threshold is repeatedly exceeded. [Insert Figure 2]
The following principles of the PLST model provide the foundation of care for the PWD:
These principles are used to equip caregivers with the knowledge and skills to recognize the subtle behavioral changes indicative of heightened anxiety in an effort to provide timely and appropriate intervention. Efforts to establish a more effective means of behavioral management in PWD is done in an effort to diminish the adverse outcomes experienced by both the PWD and their caregiver (formal and informal). [Insert Figure 3]
Principles of the PLST model have been used as the basis for care in persons with dementia since its inception in 1985. A growing body of research supports the application of its use in a variety of care settings (i.e., nursing homes, Alzheimer’s special care units, adult day care, and hospital settings). Benefits to the caregiver include: decreased depression, diminished uncertainty and unpredictability associated with managing the secondary symptoms of dementia, more positive appraisal of the stressors and burden associated with the caregiving experience, higher levels of satisfaction with the caregiving role, and reduced negative reactions to behavioral symptoms.
Key search terms:
Progressively Lowered Stress Threshold Model, dementia, caregiver, Alzheimer’s disease, stress, agitation,
An experimental 3-year study evaluated the effectiveness of a family caregiver training program based on the PLST model (NIH/NINR 5R01NR03234, PI: Kathleen C. Buckwalter, PhD, RN, FAAN). Table 1 (attached) provides a comparison of the intervention protocols for caregivers in the experimental (PLST) and comparison groups. Content is delineated by activities that take place in both home Visit #1 and Visit #2.
Both experimental and comparison group members received a Caregiver’s Notebook that contained a variety of supportive materials such as a Home Safety Checklist, “Caregiving at a Glance” tip sheet with information on items such as sleeping, giving medications, bathing, toileting and grooming, activities, nutrition and communication, recommended readings for family members caring for memory-impaired elders , and a directory of Senior Services available in their county or region of the state. Additional information was provided on communication skills, What Activities Work Best?, common behavioral problems and bathing, as these issues were reported as being most challenging to caregivers in our pilot study.
Please see Table 2 (attached) for a complete listing of contents contained in the Caregiver Notebooks as well as a comparison of materials received by caregivers in the experimental (PLST) versus comparison group. For example, caregivers in the PLST-intervention group received information about the PLST model, patterns of dysfunctional behavior in dementia, care plans to compensate for behavioral changes, and a series of data-based interventions (e.g Managing Delusions and Hallucinations, Reality vs. Validation, etc) that comparison group caregivers (who received the latest edition of the 36 Hour Day by Mace and Rabins as well as brochures and newsletters), did not.
A video, entitled “As the Memory Fades…the Challenge Begins: Understanding and Coping with Behavior Problems Related to Memory Loss) is also available. The video, supported in part by a grant from the the Scottish Rite Foundation of Iowa, illustrates principles of the PLST model using real life care recipients and caregivers.
An annotated bibliography is provided as a foundation of information to assist formal and informal caregivers in their understanding of the PLST model and application for an individualized plan of care for the PWD.
Hall, G. R., & Buckwalter, K. C. (1987). Progressively lowered stress threshold: A conceptual model for care of adults with Alzheimer’s disease. Archieves of Psychiatric Nursing, 1(6), 399-406.
This is the original article that introduces and describes the PLST model.
Hall, G. R., Gerdner, L., Zwyart-Stauffacher, M., & Buckwalter, K. C. (1995). Principles of non-pharmacological management: Caring for people with Alzheimer's disease using a conceptual model. Psychiatric Annals, 25(7), 432-440.
This article provides refinement and expansion of the PLST model. A case study is included to illustrate application of the model. Assessment is linked to the interaction of symptom clusters, levels of patient behaviors, and staging of the disease process. Principles of the PLST model are applied to develop an individualized plan of care in an effort to maximize a safe functional level while controlling for triggers that precipitate dysfunctional behavior.
Gerdner, L. A., Hall, G. R., & Buckwalter, K. C. (1996). Caregiver training for people with Alzheimer's based on a stress threshold model. Image: Journal of Nursing Scholarship, 28(3), 241-246.
The purpose of this article is to discuss a caregiver training protocol based on the PLST model for the management of dementia. More specifically the protocol is examined according to criteria proposed by McCloskey and Bulechek (1992) for a nursing intervention. Criteria includes: a) characteristics of the nursing diagnosis, b) research based for the intervention, c) desired patient outcomes, d) acceptability to the patient, e) capability of the nurse and f) feasibility for doing the intervention.
Hall, G. R., Buckwalter, K. C., Stolley, J. M., Gerdner, L. A., Garand, L., Ridgeway, S., & Crump, S. (1995). Standardized care plan for managing Alzheimer's patients at home. Journal of Gerontological Nursing, 21(1), 37-47, 48-49.
The article begins with a brief literature review that addresses the challenges faced by family members for in-home care of a PWD. Family caregivers often receive inadequate support and training for this role. A brief overview of the PLST model is provided and serves as the basis for a standardized care plan that targets some of the most disturbing behavioral symptoms associated with dementia. Nurses are encouraged to use this care plan as a framework for individualizing care for the PWD and as a training tool for family caregivers.
Smith, M., Hall, G. R., Gerdner, L. A., & Buckwalter, K. C. (2006). Application of the progressively lowered stress threshold (PLST) model across the continuum of care. Nursing Clinics of North America, 41 (1), 57-81.
An overview of the PLST model is provided with an expanded explanation of the six principles of care. A vignette is used to illustrate the application of these principles across the continuum of care for an elder woman diagnosed with probable Alzheimer’s disease. The PLST model provides a useful approach for planning and evaluating care across a variety of settings including: (home care with supplemental community services (i.e., adult day care), assisted living, hospitalization, skilled care, and an Eden Alternative nursing facility. Principles can be applied by knowledgeable nurses with diverse specialty backgrounds and taught to support staff and family caregivers.
Gerdner, L. A., Buckwalter, K. C., & Hall, G. R. (2005). Temporal patterning of agitation and stressors associated with agitation: Case profiles to illustrate the progressively lowered stress threshold model. Journal of the American Psychiatric Nurses Association, 11 (4), 215-222.
This study examined temporal patterning of stressors associated with agitation in PWD as postulated in the PLST model. Case profiles were developed to illustrate the factors that contribute to stress: a) physical stressors (e.g. pain, discomfort, infection, b) misleading stimuli or inappropriate stimuli, c) change of environment, caregiver, or routine; d) internal or external demand that exceed functional capacity; e) fatigue; and f) affective response to perceptions of loss. Each case profile is followed by a discussion to help nurses identify the subtle cues of cumulative stress with suggestions for timely and appropriate intervention.
Gerdner, L. A. (1999). Individualized music intervention protocol. Journal of Gerontological Nursing, 25(10), 10-16.
Individualized music is an evidence-based intervention for the management of agitation in PWD. This intervention uses the PLST model as the conceptual foundation to explain the effects of stress in PWD and applies these principles in an effort to achieve optimum effect for timing of the intervention.
Training qualifications and guidelines for those delivering the intervention:
Table 3 provides the outline used by nurses for training family caregivers in the principles and application of the PLST model for the care of PWD.
An individualized needs assessment is a critical component to this process. The Behavioral Assessment for Low Stimulus Care Plan (BALSCP) was developed to assist in the identification of specific problems amenable to the PLST intervention (see attached). This data provided by the caregiver allows the model to be tailored for an individualized plan.
The costs of implementing the intervention were not evaluated in this project and unavailable.
Caveats/ limitations on the implementation of this intervention:
There are limitations in the use of the PLST model in planning care for persons with certain dementing illnesses such as Pick’s disease, Korsakoff’s psychosis, diffuse Lewy body syndrome, frontal lobe dementias, dementia pugilistica, certain toxic or drug-induced dementias, dementia in persons who have long histories of psychosis, and possibly AIDS encephalopathy. Limited success has also been found with persons whose premorbid personality included violence as a normal coping mechanism (Hall, Gerdner, Zwygart-Stauffacher, & Buckwalter, 1995). Finally, the PLST-model intervention is most effective for caregivers of persons in the early through middle stages of the disease. It is not targeted for caregivers of persons in the endstage or terminal stages of dementia.
RESEARCH FINDINGS AND OTHER IMPORTANT REFERENCES
Buckwalter, K. C., Gerdner, L. A., Hall, G. R., Kelly, A., Kohout, F., Richards, B., & Sime, M. (1999). Effects of family caregiver home training based on the progressively lowered stress threshold model. In S. H. Gueldner & L. W. Poon (Eds.), Gerontological nursing issues for the 21st century: A multidisciplinary dialogue commemorating the international year of older persons (pp. 81-98). Sigma Theta Tau International: Nursing Center Press.
Buckwalter, K. C., Gerdner, L., Kohout, F., Hall, G. R., Kelly, A., Richards, B., & Sime, M. (1999). A nursing intervention to decrease depression in family caregivers of persons with dementia. Archives of Psychiatric Nursing, 13(2), 80-88.
Garand, L., Buckwalter, K. C., Lubaroff, D. M., et al. (2002). A pilot study of immune and mood outcomes of a community-based intervention for dementia caregivers. The PLST intervention. Archives of Psychiatric Nursing, 16, 156-167.
Gerdner, L.A., Buckwalter, K. C., & Reed, D. (2002). The impact of a psychoeducation nursing intervention on frequency of and response to behavioral problems and functional decline in dementia. Nursing Research, 51(6), 607-618.
Smith, M., Gerdner, L. A., Hall, G., & Buckwalter, K. C. (2004). The history, development, and future of the progressively lowered stress threshold model: A conceptual model for dementia care. Journal of the American Geriatrics Society, 52(10), 1755-1760.
Stolley, J. M., Reed, D., & Buckwalter, K. C. (2002). Caregiving appraisal and interventions based on the progressively lowered stress threshold model. American Journal of Alzheimer’s Disease and other Dementias, 17, 113-132.