Journal of Speech Pathology & Therapy
Open Access

Alzheimer’s disease; Dementia; Cognitive decline; Speech impairment; Phonological impairment; Language deficits; Communication difficulties; Neurodegeneration; Language processing; Neuroimaging; Comprehensive language assessment; Speech therapy

Introduction

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that affects millions of people worldwide, making it the most common cause of dementia. The disease is characterized by the gradual decline of cognitive functions, which includes memory, language, and speech [1]. Communication difficulties, especially in speech and phonology, are prevalent in individuals with AD, significantly impacting their daily life and social interactions. This review aims to consolidate existing research on speech and phonological impairments across different stages of Alzheimer’s disease.

Speech and phonological impairment in alzheimer’s disease:

Early stages: During the early stages of Alzheimer’s disease, subtle changes in speech and phonology can be observed. Individuals may experience difficulty finding the right words, a condition known as anomia. This word-finding difficulty can cause increased hesitations and pauses during conversation [2]. Moreover, there may be a reduction in fluency, and individuals may struggle to maintain a smooth and coherent flow of speech. They might also use filler words, such as “um” or “uh,” more frequently, as they search for appropriate words. These initial signs of speech and phonological impairment are often overlooked or misattributed to normal aging or benign memory lapses. As a result, the diagnosis of Alzheimer’s disease might be delayed, hindering early interventions that could potentially slow down the progression of the disease and improve the individual’s quality of life [3].

Mid-stages: As Alzheimer’s disease progresses into the mid-stages, speech and phonological impairments become more apparent and pronounced. Speech may become less intelligible, meaning it becomes increasingly difficult for others to understand what the individual is saying. Phonological errors, such as sound substitutions or omissions, can occur more frequently, leading to mispronunciations and further challenges in communication. The overall rate of speech production may decrease during this stage, affecting the flow and rhythm of conversation [4]. Individuals may take longer to respond to questions or participate in discussions, leading to potential communication breakdowns and misunderstandings. Furthermore, they may struggle to comprehend complex language, including following multi-step instructions or understanding abstract concepts, which further hinders effective communication.

Late stages: In the advanced stages of Alzheimer’s disease, speech and phonological abilities are severely impaired. Expressive language becomes highly limited, and individuals may rely more on non-verbal communication, such as gestures, facial expressions, or body language, to convey their needs and emotions. Pronunciation errors become more frequent and prominent, making it increasingly challenging for caregivers and loved ones to understand the individual’s intentions and desires [5,6]. The loss of language abilities in late-stage AD significantly impacts social interactions, leading to feelings of frustration and isolation for both the affected individual and their loved ones. Communication becomes a major challenge, and individuals may withdraw from social engagements, further exacerbating the sense of isolation and loneliness. Speech and phonological impairment in Alzheimer’s disease have farreaching effects on affected individuals and their caregivers. Early recognition of these impairments is crucial for timely diagnosis and intervention, which can help maintain functional communication and improve the overall quality of life for individuals living with Alzheimer’s disease [7]. As the disease progresses, speech and language deficits become more pronounced, leading to significant challenges in daily communication and social interactions. By consolidating existing research on speech and phonological impairments across different stages of Alzheimer’s disease, this review sheds light on the importance of understanding and addressing these deficits to provide better care and support for individuals affected by this debilitating condition. Further research is warranted to develop targeted therapeutic approaches that can ameliorate speech and language difficulties and enhance the wellbeing of those living with Alzheimer’s disease [8].

Underlying mechanisms: The exact mechanisms that underlie speech and phonological impairment in Alzheimer’s disease are complex and not yet fully understood. However, significant progress has been made in identifying some of the key factors contributing to these deficits. Neuroimaging studies have played a crucial role in unraveling the structural and functional changes in the brain associated with language deficits in AD. Language processing is a complex cognitive function that relies on the coordination of various brain regions. In Alzheimer’s disease, there is a selective and progressive degeneration of brain areas crucial for language processing. Among these regions, the left temporal and frontal lobes are particularly affected [9,10]. The left temporal lobe, especially the posterior portion known as Wernicke’s area, is essential for language comprehension. Damage to this region can lead to difficulties in understanding spoken and written language. The left frontal lobe, particularly Broca’s area, is responsible for language production and articulation. Impairments in this area can result in speech production difficulties, including the inability to express thoughts fluently and accurately. The degeneration of these language-related brain regions contributes to the speech and phonological impairments observed in individuals with Alzheimer’s disease. As the disease progresses, the damage to these areas worsens, leading to more severe language deficits.

Amyloid plaques and tau tangles: Alzheimer’s disease is characterized by the abnormal accumulation of two proteins in the brain: amyloid-beta plaques and tau tangles [11]. Amyloid-beta plaques are formed by the aggregation of amyloid-beta protein, while tau tangles result from the abnormal accumulation of tau protein within nerve cells. These protein aggregates disrupt normal brain function and contribute to the progressive neurodegeneration observed in Alzheimer’s disease. The accumulation of amyloid-beta plaques and tau tangles in brain areas involved in language processing, such as the left temporal and frontal lobes, can directly affect language functions. This interference with neural connections and signaling pathways impairs the brain’s ability to process and produce language, resulting in speech and phonological deficits.

Diagnostic and therapeutic approaches: Early detection of speech and phonological impairment in Alzheimer’s disease is crucial to initiate timely interventions that can help maintain functional communication and improve the overall quality of life for affected individuals. Comprehensive language assessments play a vital role in identifying these deficits and formulating appropriate treatment plans [12]. A thorough evaluation of language abilities, including speech production, phonological processing, and language comprehension, is essential to diagnose speech and phonological impairments accurately. Speech and language pathologists (SLPs) conduct these assessments, which may involve tasks such as picture naming, repeating phrases, understanding complex instructions, and verbal fluency tests.

Speech therapy and communication-focused interventions: Speech therapy is a cornerstone of intervention for individuals with Alzheimer’s disease experiencing speech and language deficits. SLPs work with patients to address specific communication challenges and develop personalized treatment plans [13-15]. These interventions aim to:

a) Maintain functional communication: By focusing on practical communication skills, speech therapy helps individuals maintain their ability to express basic needs and participate in daily conversations.

b) Improve speech intelligibility: Techniques such as articulation exercises and voice training can enhance speech clarity and intelligibility, making it easier for others to understand the individual.

c) Facilitate alternative communication: In later stages of the disease when verbal communication becomes extremely challenging, SLPs may explore alternative communication methods, such as using augmentative and alternative communication (AAC) devices.

d) Enhance quality of life: Effective communication is vital for maintaining social connections and emotional well-being. Communication-focused interventions can improve the overall quality of life for individuals with Alzheimer’s disease and reduce feelings of frustration and isolation.

Conclusion

Speech and phonological impairment in Alzheimer’s disease represents a critical aspect of the multifaceted cognitive decline experienced by affected individuals. Throughout the course of the disease, language difficulties evolve and become increasingly pronounced, profoundly impacting the affected individual’s daily life and social interactions. Early recognition of these deficits is paramount as it allows for more effective management and intervention strategies to be implemented. The early stages of Alzheimer’s disease may present subtle changes in speech and phonology, often mistaken for normal aging or benign memory lapses. This delayed recognition can hinder early diagnosis and interventions, preventing individuals from accessing appropriate support and care when they need it most. However, through comprehensive language assessments and vigilant monitoring, healthcare professionals can identify speech and phonological impairments early on, enabling timely intervention to support language function and communication skills. Unraveling the underlying mechanisms of speech and phonological impairment in Alzheimer’s disease remains an area of active research. Neuroimaging studies have provided valuable insights into the structural and functional changes occurring in language-related brain regions. Further research is necessary to understand the precise interactions between these brain areas, the accumulation of amyloid plaques, and tau tangles, and their role in language deficits. Advancing our understanding of these mechanisms will aid in the development of targeted therapies that can ameliorate communication difficulties and potentially slow down the progression of language impairments in Alzheimer’s disease. Improved understanding and intervention strategies for speech and phonological impairment can have far-reaching benefits. By providing effective support and tailored therapies, the quality of life and wellbeing of individuals living with Alzheimer’s disease can be significantly enhanced. Maintaining functional communication and improving speech intelligibility can foster greater social engagement and emotional connection, mitigating the sense of isolation and frustration that often accompanies language deficits. Furthermore, alleviating the burden on caregivers and loved ones is equally crucial. Communication-focused interventions and therapies can equip caregivers with effective tools to facilitate meaningful interactions with their loved ones. Enhanced communication skills enable caregivers to provide more compassionate and informed care, strengthening their ability to meet the complex needs of individuals with Alzheimer’s disease. In conclusion, speech and phonological impairment in Alzheimer’s disease have far-reaching implications for individuals living with this devastating condition. Early recognition and intervention hold the potential to enhance the management of language deficits and provide significant support to those affected. Further research into the underlying mechanisms and the development of targeted therapies are essential to improving the lives of individuals with Alzheimer’s disease and easing the burden on caregivers and loved ones. A comprehensive approach that combines scientific understanding, compassionate care, and evidence-based interventions is fundamental to fostering a more inclusive and supportive environment for individuals living with Alzheimer’s disease.

Acknowledgement

Not applicable.

Conflict of Interest

Author declares no conflict of interest.

1. Emery VOB (2000) Language Impairment in Dementia of the Alzheimer Type: A Hierarchical Decline? Int J Psychiatry Med 30:145-164.

Indexed at, Google Scholar, Crossref

2. Murphy J, Oliver TM, Cox S (2010) Talking Mats and involvement in decision making for people with dementia and family carers. JRF.

Google Scholar

3. Patel D, Krishnaswami S, Steger E, Conover E, Vaezi M, et al. (2018) Economic and survival burden of dysphagia among inpatients in the United States. Dis Esophagus 31:1-7.

Indexed at, Google Scholar, Crossref

4. Omura K, Komine A, Yanagigawa M, Chiba N, Osada M (2019) Frequency and outcome of post-extubation dysphagia using nurse-performed swallowing screening protocol. Nurs Crit Care 24:70-75.

Indexed at, Google Scholar, Crossref

5. Savundranayagam MY, Hummert ML Montgomery RJV (2005) Investigating the Effects of Communication Problems on Caregiver Burden. J Gerontol B Psychol Sci Soc Sci 60:48-55.

Indexed at, Google Scholar, Crossref

6. Perren A, Zürcher P, Schefold J (2019) Clinical approaches to assess Post-extubation Dysphagia (PED) in the critically ill. Dysphagia 34:475-486.

Indexed at, Google Scholar, Crossref

7. St Louis KO, Reichel I, Yaruss JS, Lubker BB (2009) Construct and concurrent validity of a prototype questionnaire to survey public attitudes toward stuttering. J Fluency Disord 34:11-28.

Indexed at, Google Scholar, Crossref

8. St Louis KO, Roberts PM (2010) Measuring attitudes toward stuttering: English-to-French translations in Canada and Cameroon. J Commun Disord 43:361-377.

Indexed at, Google Scholar, Crossref

9. St Louis KO, Roberts PM (2013) Public attitudes toward mental illness in Africa and North America. Afr J Psychiatry 16:123-133.

Indexed at, Google Scholar, Crossref

10. Weidner ME, St Louis KO, Burgess ME, LeMasters SN (2015) Attitudes toward stuttering of nonstuttering preschool and kindergarten children: A comparison using a standard instrument prototype. J Fluency Disord 44:74-87.

Indexed at, Google Scholar, Crossref

11. Valente AR, Jesus L, Leahy M, St Louis KO (2014) Attitudes and knowledge of the Portuguese population about stuttering. Eur Sympos Fluency Disord.

Google Scholar

12. Northcott S, Simpson A, Moss B, Ahmed N, Hilari K (2017) How do speech-and-language therapists address the psychosocial well-being of people with aphasia? Results of a UK online survey. Int J Lang Commun Disord 52:356-373.

Indexed at, Google Scholar, Crossref

13. Weidner ME, St Louis KO (2014) The Public Opinion Survey of Human Attributes–Stuttering/Child (POSHA–S/Child). Morgantown, West Virginia.

Google Scholar

14. St Louis KO, Sonsterud H, Carlo EJ, Heitmann RR, Kvenseth H (2014) Public attitudes toward-and identification of-cluttering and stuttering in Norway and Puerto Rico. J Fluency Disord 42:21-34.

Indexed at, Google Scholar, Crossref

15. St Louis KO, Williams MJ, Ware MB, Guendouzi J, Reichel I (2014) The Public Opinion Survey of Human Attributes-Stuttering (POSHA-S) and Bipolar Adjective Scale (BAS): Aspects of validity. J Commun Disord 50:36-50.

Indexed at, Google Scholar, Crossref