Lade Inhalt...

Alzheimer’s disease and language

Hausarbeit (Hauptseminar) 2008 36 Seiten

Anglistik - Linguistik

Leseprobe

Table of contents

Table of contents

List of figures

1 Introduction
1.1 Procedure of the Work

2 The study of Neurolinguistics
2.1 The brain
2.2 Language and the human brain

3 Dementia
3.1 Dementia of the Alzheimer’s type
3.1.1 Historical background
3.1.2 Causes of Alzheimer’s
3.1.3 Diagnosis
3.1.4 Therapy
3.1.5 The Alzheimer’s brain
3.1.6 Speech disorders in Alzheimer’s patients
3.1.6.1 Functional language abilities: reading, writing, understanding
3.1.6.2 Word finding/lexicon/semantic lexicon
3.1.6.3 Syntax
3.1.6.4 Discourse
3.1.6.5 Spared language abilities
3.1.6.6 Alzheimer’s in bilinguals

4 Analysis of linguistic Alzheimer’s symptoms in the film ‘Iris’
4.1 The film
4.2 Depicted speech problems

5 Conclusion
5.1 Open problems and outlook

Appendix

Bibliography
Literature
Internet Sources
Films

List of figures

Figure 1: The human brain (Alzheimer’s Disease and Education and Referral Center 2008:11)

Figure 2: Language areas of the left brain hemisphere (Obler and Gjerlow 1999: 6)

Figure 3: The surface of the cerebral hemispheres from the side, showing some specific functional areas (Jaques and Jackson 2000: 9)

Figure 4: PET-Scans of a normal brain and a brain with Alzheimer’s. Red areas show high activity. (www.alzheimers.org)

Figure 5: Alzheimer’s disease spreads through the brain (Alzheimer’s Disease and Education and Referral Center 2008: 32)

Figure 6: Schrinkage of the brain in Alzheimer’s (http://www.ahaf.org/alzdis/about/Brain_Neurons_AD_Normal.htm)

Figure 7: Plaques and tangles in an Alzheimer’s patient’s brain (http://www.ahaf.org/alzdis/about/AmyloidPlaques.htm)

Figure 8: Writing example of an Alzheimer’s patient. Months counted after her first examination. (Mielke and Kessler 1994:18)

1 Introduction

Iris has got more than one world going on inside her head - a secret world. [...] I’m the only friend that knows of her secret world. [...] It’s like in a fairy story: I’m the young man in love with a beautiful maiden. Who disappears into an unknown and mysterious world every now and again, who always comes back.

(John about Iris in the Film ‘Iris’ 2001)

John said this about his novelist girlfriend when they both were young. Unfortunatley in Iris lasts years, when she suffered from Alzheimer’s she also lived in her own world but would never come back again.

Having experienced our neighbour gradually losing his memory when I was about twelve years old Alzheimer’s disease to me has always been a topic I could relate to. Of course when we were kids we often found it funny that our neighbour, who had interesting stories to tell us, would talk about the same events over and over again. The older we got the more we became aware of the tragic behind this disease not necessarily for the patients but definetly for the ones who take care of them. Often the patients don’t realize that they tell stories more than once, but the caretakers who also often have to search for their consigned when they once again forgot the way home or can’t articulate themselves properly anymore have a very hard and often ennnerving task.

This paper is focusing on the impacts of Alzheimer’s disease on language production, since we won’t be able to explain this complex desease in medical detail. For introductory reasons a short insight into language and the brain in general will be given. From a neurolinguistic point of view we will then eleborate on the various brain areas affected by Alzheimer’s and on the various speech deficiencies that can occur within an Alzheimer’s patient. As an example of how big the impact of Alzheimer’s disease on language is, the main character in the film ‘Iris’, a dementic woman, will be examined with a focus on language problems.

1.1 Procedure of the Work

Chapter two gives a brief overview on the study of neurolinguistics and the recent discussions on where language is produced in the brain. Dementia and especially dementia of the Alzheimer’s type are in the focus of chapter three. In this chapter also special language problems of Alzheimer’s patients are being explained. In chapter four the film ‘Iris’ that depicts the life of a woman suffering from Alzheimer’s is analyzed in terms of her speech deficiencies that are depicted in the film. A conclusion is drawn in the last chapter also giving an outlook for further studies.

2 The study of Neurolinguistics

It was in the nineteenth century that neurolinguistics emerged from phrenology (the study of linking human characteristics with the relative size of skull areas) and psychiatry (the study of mental illness) (see Obler and Gjerlow 1999: 3).

According to Obler and Gjerlow the study of neurolinguistics is the study of “how the brain (‘neuro’) permits us to have language (‘linguistics’).” (1999: 1) Center of the study are the brain and nerve systems and language and how damage to the brain and nerve systems affects linguistic behavior and therefore the question is to be answered where language lies (see ibid.). Main actors in the field of neurolinguistics are neurologists, linguists and often also psychologists, speech-language pathologists and cognitive scientists all qualified in the field of neurolinguistics (see Obler and Gjerlow 1999: 2).

The field of linguistics in neurolinguistics is concerened with phonology, morphology, syntax, discourse, semantics, pragmatics and lexis (see Obler and Gjerlow 1999: 8). The relevant entities of language that are examined are oral, written and visual-gestural language use (see ibid.). The objects to be examined in neurology are the various areas of the brain. The broadest devision being between the cortex (external surface) and the internal space, called the subcortical areas (see ibid.).

2.1 The brain

Humans have two nervous systems one being the central nervous system (brain and spinal cord) and the other being the peripheral nervous system (system that regulates body functions such as breathing) (see Obler and Gjerlow 1999: 13f.). With neurolinguistics the focus is put on the first system described.

illustration not visible in this excerpt

Figure 1: The human brain (Alzheimer’s Disease and Education and Referral Center 2008:11)

In the following the main areas of the brain are described according to übler and Gjerlow (1999: 18f.) :

The cerebrum and the cerebellum are divided into a left and a right hemisphere that are connected through fiber bundles. The most important fiber bundle out of these is the corpus callosum. The surface of the cerebrum is called cortex and consists mostly of nerve cell bodies and since it appears grey when dissected is also refered to as ‘grey matter’. It is distinguished by its convolutions. They are called gyri and sulci. The gyri and sulci form four important lobes: the frontal lobe, the parietal lobe, the occipital lobe and the temporal lobe. Fissures are between the various lobes: the Rolandic fissure separates the frontal and the parietal lobes and the Sylvian fissure separates the frontal and parietal lobes from the temporal lobe and runs through the language area. The anterior region of the brain is the frontal lobe, the parietal and the occipital lobe belong to the posterior region of the brain.

Underneath the cortex lie the subcortical regions refered to as ‘white matter’. They consist of nerve cell fibres. Since the cortex surrounds the subcortical regions, grey matter can also be found more inside the brain, the thalamus and the hypothalamus are considered ‘grey matter’ as well (see übler and Gjerlow 1999: 21). The internal capsule is considered as ‘white matter’ but is “implicated in aphasia.” (ibid.) “Also the temporal isthmus along with the arcuate fasciculus connects anterior and posterior cortical areas involved in language.” (ibid.) Most crucial for language production is the cortex, but also the subcortical areas do play a role in language production (see übler and Gjerlow 1999: 18).

2.2 Language and the human brain

How do scientists examine where language is situated in the brain if so at all? Most of the research is done on patients that suffered brain damage and are now having problems in speech production of any kind. It is because of this that this paper focuses on Alzheimer’s disease to explain some language disorders. But there are also other methods to examine the brain: cortical stimulation allows us today to directly stimulate the brain by opening up the skull (see Obler and Gjerlow 1999: 9). An easier and less dangerous way is the positron emission tomography (PET-scans) that shows brain activity on a computer scan (see ibid.).

As Obler and Gjerlow describe: “Neurolinguistics has yet to develop a single large-scale unified theory acceptable to all [...] neurolinguists.” (1999: 3) This paper therefore presents some of the sometimes controversial theories on language and the brain.

There are two major schools in the study of neurolinguistics. Localizationalists claim that of the two brain hemispheres the left one is mainly responsible for language, especially the central parts of the outer surface and areas within the left-hemisphere cortical language area (see Obler and Gjerlow 1999: 9). The latter ones being devided in areas for producing language and areas for understanding language (see ibid.). Famous supporter of this theory are Broca, Goodglass, Kaplan and Geschwind (see ibid.).

Holists instead focus on how the different areas of the brain interconnect (Obler and Gjerlow 1999: 10). “Holists focus more on the ways language is dependent on cognitive abilities such as memory, abstract thinking, etc.” (ibid.) Famous supporter of this school were Goldstein and Jackson (see ibid.). Holists don’t link language to special areas of the brain (see ibid.).

Main areas of interest in neurolinguistics are Broca’s area and Wernicke’s area.

Broca found out in 1861 that “the area of the frontal lobe just in front of the Sylvian fissure” (Obler and Gjerlow 1999: 33) has to do with language function. Wernicke pointed in 1874 at an area in the back of the Sylvian fissure and situated behind Heschl’s gyrus that when damaged caused linguistic deficits (see ibid.).

As can be seen in the picture below, Broca’s area is said to be responsible for speech planning and output, maybe even for syntax whereas Wernicke’s area is responsible for speech comprehension (see Obler and Gjerlow 1999: 6).

illustration not visible in this excerpt

Figure 2: Language areas of the left brain hemisphere (Obler and Gjerlow 1999: 6)

So far these two centers of language production have been discovered however language is not uniquely produced in these two areas since “language impairment sometimes occurs after brain damage outside the classical language areas.” (Dabrowska 2004: 41) “Aphasic like symptoms may occur after damage to subcortical areas like the basal ganglia and the thalamus.” (ibid.) Today therefore the view is that various regions in the brain and not only these two classical language areas are involved in language processing also because a damage of one of these regions does not always lead to language impairment (see ibid.).

A tertiary association area is the parietal lobule being situated behind Wernicke’s area and consisting of the supramarginal and the angular gyrus (see Obler and Gjerlow 1999: 26). This area connects the secondary association areas namely the temporo, parieto and occipital lobe (see ibid.).

An important fact for the search of the language area is that “stimulation of a cortical area in one hemisphere usually makes the muscles on the opposite side of the body move. This is because most of the nerve fibres cross over to the opposite or contralateral side.” (Obler and Gjerlow 1999: 23)

The area of the brain called motor cortex is where nerve impulses that control the musculature originate (see Obler and Gjerlow 1999: 23). The location of this area is illustrated in figure 3 in the appendix. This area is important to produce language (see ibid.). Heschl’s gyrus, situated in the temporal lobe, makes it possible for us to recieve auditory stimuli (see Obler and Gjerlow 1999: 24). Between the temporal and the parietal lobe lies the planum temporale, a part of the cortex (see Obler and Gjerlow 1999: 25). It is larger in the left hemisphere than in the right and contiguous to the language areas and therefore considered as a secondary association area for language (see ibid.). In the secondary association areas “a higher level of processing takes place” (ibid.).

Obler and Gjerlow state that “recent studies suggest that approximately 97% of the population has language represented predominantly in the left hemisphere. Of the remaining 3%, most are left-handed [...] this means that the majority of left-handed individuals also have language represented in their left hemisphere.” (1999: 28) These numbers can be verified with a Wada test where an anesthetic is injected into one of the brain hemisphere. The majority of the patients can’t speak when their left hemisphere is disabled (see Obler and Gjerlow 1999: 28f.).

Curtiss and de Bode state: “Nearly a third of the right hemispherectomised patients had no productive language at all, compared to 16.7 per cent of the left hemispherectomies, which suggests that the right hemisphere plays an important role in language acquisition.” (quoted from Dabrowska 2004: 42) It is also suggested that for different languages overlapping but also different brain areas are activated as experiments showed (see Dabrowska 2004: 46). Dabrowska concludes as well, that “grammatical knowledge does not reside in the pattern of connections in Broca’s area.” (2004: 47) All in all she states: “...linguistic knowledge is represented in a redundant manner in various regions of the brain, with the language areas acting as a kind of central switchboard.” (2004: 48)

It is also suggested that language functions are more widely distributed in children than in adult persons since “children are likely to have a mild aphasia after just about any kind of brain damage, including damage to the right hemisphere and the non-linguistic parts of the left hemisphere” (Dabrowska 2004: 42). But here one could argue that a child’s brain is a lot smaller than this of an adult and therefore the regions could be harder to detect and maybe even still growing and therefore have a fuzzy boundary. And even persons who had to undergo a removal of the left hemisphere don’t lack speech capability completely (see ibid.).

As of today “modern aphasiologists are still not entirely in agreement over the extent to which specific language functions are subserved by specific brain areas.” (Obler and Gjerlow 1999: 33)

3 Dementia

The definition according to the World Health Organisation is as follows:

Dementia is a syndrom due to disease of the brain, usually of a chronic or progressive nature, in which there is disturbance of multiple cortical functions, calculations, learning capacity, language and judgement. Consciousness is not clouded. Impairments of cognitive function are commonly accompanied, and occasionally preceded by deterioration in emotional control, social behaviour, or motivation. (in Jacques and Jones 2000: 2)

Jacques and Jackson state that dementia is “a progressive failure of many cerebral functions.” (2000: 1)

Obler and Gjerlow cut it short and state: “Dementia is the loss of intellectual abilities [and] is caused by the deterioration of brain tissue.” (Obler and Gjerlow 1999: 91) However dementia does not “result in obvious brain damage in distinctly localized areas of the brain the way aphasias do. Rather they appear as more generalized atrophy.” (see ibid.) There are two types of dementias: cortical and subcortical dementia (see ibid.). In the first one the cellular changes mainly occur in cortical areas and in subcortical dementia it is vice versa (see ibid.). Alzheimer’s is the most common cortical dementia, in one-third of Parkinson’s patients occurs the subcortical dementia (see Obler and Gjerlow 1999: 92).

3.1 Dementia of the Alzheimer’s type

3.1.1 Historical background

The name of the disease derives from the man who explored it: Aloys Alzheimer. He was born in 1864 in Marktbreit, Germany and studied medical science in various cities around Germany, his special field being neuropathology (see Maurer 1993: 2). Until his death in 1915 he worked as a professor at the psychiatry of the University of Breslau (see ibid.). In 1901 a 51-year old woman called Auguste D. was brought to him who suffered from memory loss, paranoia, disorientation and difficulties in speaking and understanding (see Maurer 1993: 3). After her death in 1906 Alzheimer was allowed an autopsy of her brain and he described his findings in the presentation ‘Über einen eigenartigen, schweren Erkrankungsprozess der Hirnrinde’ at the 37th meeting of the ‘Südwestdeutschen Irrenärzte’ in Tübingen (see ibid.). This was the first description of what was later to be called dementia of the Alzheimer’s type (see ibid.).

[...]

Details

Seiten
36
Jahr
2008
ISBN (eBook)
9783640967070
Dateigröße
1014 KB
Sprache
Deutsch
Katalognummer
v147279
Institution / Hochschule
Ernst-Moritz-Arndt-Universität Greifswald – Institut für Anglistik/Amerikanistik
Note
1,3
Schlagworte
Alzheimer Alzheimer's disease Sprache und Alzheimer Language and Alzheimer's disease Neurolinguistik Neurolinguistics

Autor

Teilen

Zurück

Titel: Alzheimer’s disease and language