SPEECH AND LANGUAGE

Speech and language difficulty commonly affects individuals with dementia and other neurological conditions. One may experience deficits in the form of verbal expression (i.e. word-finding difficulty) or comprehension (i.e. difficulty understanding speech). Language function includes speaking, understanding speech, repeating things we have heard, naming objects, reading, and writing. “Aphasia” is the term used to describe an acquired loss of language function, and may manifest as impaired expression, comprehension, or both.

Anatomy of the Brain that Governs Speech and Language

Broca’s Area
Broca’s area, located in the left hemisphere, is associated with speech production and articulation. Our ability to articulate ideas, as well as use words accurately in spoken and written language, has been attributed to this crucial area.

Wernicke’s Area
This critical language area which connects to Broca’s area via a neural pathway, is primarily involved in the comprehension. Historically, Wernicke’s area has been associated with language processing, whether it is written or spoken.

Angular Gyrus
The angular gyrus allows us to organize language and thoughts, as it is located in close proximity to other critical brain regions such as the parietal lobe which processes tactile sensation, the occipital lobe which is involved in visual analyses, and the temporal lobe which processes sounds. The angular gyrus allows us to associate a perceived word with different images, sensations, and ideas.

(Wernicke-Geschwind model of language processing)

Impact of Neurological Illness

Alzheimer’s Disease (AD)
In Alzheimer’s disease, the most common cause of dementia, language functioning may be relatively spared in the early stages of the disease, but it is likely to decline substantially in the mid to late stages. People with AD often have difficulty with language expression, word fluency, and naming objects. Syntax and comprehension of language are generally preserved in the early stages, however, in the later stages, speech may become halting due to word-finding difficulties. In other words, he/she has great difficulty speaking in full sentences because of the great effort that is required to find the right words. Writing skills may often be compromised. Speech comprehension may be significantly impaired during the end-stage of the disease.

Frontotemporal Dementia (FTD)
Less common degenerative conditions such as those associated with frontotemporal lobar degeneration often primarily involve language deterioration, while memory may be relatively spared until later stages. Initial symptoms often involve problems with finding the right words during conversation.

NOTE: See section titled “Language Symptoms in FTD” under FTD Education section.

Corticobasal Degeneration (CBD)
CBD most commonly involves difficulty with language expression, such as word finding difficulty or speech articulation problems. Reading and writing may also be impaired.

Stroke and Injury
Individuals who have suffered neurological injuries, such as stroke or traumatic brain injury, may also experience speech and language deficits, particularly, but not exclusively, if the left side of the brain was affected. Aphasia is common in people who have left sided brain injuries. Speaking, listening, reading, and writing skills may all be affected to varying degrees. Should the stroke affect the parts of the brain that control muscles used in speech (those in tongue, mouth, and lips), speech can become slurred or slowed.

Cause of Dementia associated with Language

Primary progressive Aphasia (PPA)
PPA is caused by brain cell degeneration in the parts of the brain that control speech and language (left side of the brain in the frontal, temporal, and parietal regions that normally control language function). This type of aphasia begins very gradually and initially manifests as word finding difficulty in speaking or writing. Eventually, verbal communication, ability to understand speech, and written language also declines. Diseases which cause PPA include Alzheimer’s, Pick’s Disease, Parkinson’s, corticobasal degeneration, and Lewy Body disease.

Broca’s (Expressive or motor) Aphasia
Damage to a discrete part of a the brain in the left frontal lobe (Broca’s area) of the language-dominant hemisphere has been shown to significantly affect use of spontaneous speech and motor speech control. Words may be uttered very slowly and are poorly articulated. Speech may be labored and consist primarily of nouns, verbs, or important adjectives. Speech takes on a telegraphic character. People suffering from Broca’s aphasia have great difficulty with repetition, and a severe impairment in writing. In some patients, however, the understanding of spoken and written language may be relatively well-preserved.

Wernicke’s Aphasia
Damage to the posterior superior areas of the language dominant temporal lobe (often called Wernicke’s area) has been shown to significantly affect speech comprehension. In other words, information is heard through an intact auditory cortex in the anterior temporal lobe, however, when it arrives at the posterior association areas, the information cannot be sufficiently “translated”. In contrast to Broca’s aphasia, the person with Wernicke’s aphasia talks volubly and gestures freely. Speech is produced without effort, and sentences are of normal length. However, the person’s speech is devoid of meaning.

• Fluent, grammatically correct speech with little meaning
• Poor comprehension
• Paraphasic errors
  -calling a spoon a “fork” (semantic)
  -calling a spoon a “spood” (literal)
• Neologisms (or non-sense words)

Total (Global) Aphasia
If damage encompasses both Wernicke’s and Broca’s areas, global aphasia can occur. In this case, all aspects of speech and language are affected. Patients can say a few words at most, and understand only a few words and phrases. They usually cannot carry out commands or name objects. They cannot read or write or repeat words said to them.

Resources

See our Resources section for PPA