True, I have that abstract as well. But according to Sinha, U.; Hollen, K.M.; Rodriguez, R. & Miller, C.A.: Auditory system degeneration in Alzheimer's disease. Neurology 1993;43: 779-785
1) Senile plaques and NFTs were distrubuted throughtout the ventral nucleus of the medial geniculate body and central nucleus of the inferior colliculus in 9 of 9 AD patients. 2) Adjacent nuclei within the MGB and IC were consistently spared. 3) NFT and SP were also present in the primary auditory and auditory association cortices. 3) IN all control tissues, there were neither SP nor NFTs in any of the above sites. 4) The cochlear nuclei were normal in tissues from both AD and controls. 5) The MGBv is the majro thalamic relay for the AI function and receives fibers from neurons of the central nucleus of the IC, with projections arranged tonotopically in a lamianar pattern corresponding to a dradient of high-to-low frequency ranges. 6) IN contrast, the clnical features of presbycusis in ellderly include only high-frequency loss due to lesion peripherally. 7) These changes in the brain!
s of AD patients may provide an additional basis for altered cognitive function due ot primary sensory deafferentation
This may or may not affect peripheral hearing loss. Since the inferior colliculus is a major relay station both afferently and efferently auditory perception can be affected at the central level.
In addition, to support my stance of increased ability through stimulation, see: Inglis, F.M. & Fibiger, H.C.: Increases in hippocampal and frontal cortical acetylcholine release associated with presentation of sensory stimuli, Neurosci 1995;66: 81-86
1) Rats: hippocampal probes: auditory, visual, olfactory and tactile stimuli. 2) All stimuli increased acetylcholine release in hippocampus and cortex. 3) Reached significance: hippo: all except olfactory stimulation. \ Frontal: all except visual. 4) NO differences in amount of release in hippocampus between 3 stimuli. 5) Tactile responses resulted in the highes ACh release in the frontal. 7) Affects attentional systems mediated by frontal cortex or memory encoding by hippocampus.\
These are my notes on the articles, Please excuse spelling errors or short hand. There are numerous other articles that deal specifically with hearing loss, but more on the central auditory system and neurotransmission
see also Thiel, C.M. Friston, K.J. & Dolan, R.J.: Cholinergic Modulation of Experience-Dependent Plasticity in Human Auditory Cortex Neuron 2002;35: 567-574
There's also the Uhlmann article in JAMA of 1989.
I'll work on your specific questions when I can print them out. My printer is screwed up right now. Sorry
>From: "Ward Drennan" <firstname.lastname@example.org>
>To: "Barbara Reynolds" <email@example.com>
>Subject: Re: Inexpensive hearing aids
>Date: Sun, 28 Mar 2004 00:19:20 -0500 (EST)
>I just found somethings relevant to your comments on medline. It's going
>to be hard to take a close look at this first one seeing as the text is in
>Chinese. I think you've already referred to the 2nd.
>Zhonghua Er Bi Yan Hou Ke Za Zhi. 2003 Jun;38(3):198-201. Related
>[Hearing impairment in senile dementia of Alzheimer's type]
>[Article in Chinese]
>Wang NY, Yang HJ, Su JF, Kong F, Zhang MX, Yan B, Dong HQ, Zhang XQ, Jia
>JP, Han DM.
>Department of Otorhinolaryngology, Capital University of Medical Sciences,
>Beijing 100053, China. firstname.lastname@example.org
>OBJECTIVE: To evaluate the pure tone hearing threshold and word
>recognition score of senile dementia of the Alzheimer's disease (AD)
>patients, and to analyze the relationship between hearing loss and the
>cognition impairment. METHODS: Pure tone audiometry, word recognition
>score (WRS), acoustic immittance and auditory brainstem response (ABR) are
>used to evaluate the auditory function of 43 patients with AD and 50
>subjects of the control group. The confounding factors are controlled.
>RESULTS: The average age of 43 dementia patients was 72.7 +/- 6.4, and
>69.7% was female. Bilateral hearing thresholds are similar in all
>subjects. All indices but Mini-mental scale of equastionnaire (MMSE) of
>patients and control group were not statistically different. There was no
>significant difference in pure tone audiometry (PTA), PTA2 (dB HL, mean
>+/- s) and WRS (%, mean +/- s) between the two groups (P > 0.05),
>therefore the hearing threshold of AD group (PTA = 26.3 +/- 8.5, PTA2 =
>29.1 +/- 8.7, WRS = 85.5 +/- 15.5) is lower than that of control group
>(PTA = 23.2 +/- 10.6, PTA2 = 26.2 +/- 11.8, WRS = 87.6 +/- 16.8). No
>significant difference was found between the two groups in audiometry
>reliability, acoustic immittance and ABR (P < 0.05). CONCLUSION: No
>significant difference was found between the peripheral hearing
>dysfunction of AD patients and that normal elderly people, i.e., PTA, PTA2
>and WRS were not related to MMSE.
> Age Ageing. 2003 Mar;32(2):189-93. Related Articles, Links
>The effects of improving hearing in dementia.
>Allen NH, Burns A, Newton V, Hickson F, Ramsden R, Rogers J, Butler S,
>Thistlewaite G, Morris J.
>York House, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL,
>BACKGROUND: audiological function is impaired in people with dementia and
>poor hearing is known to exaggerate the effects of cognitive deficits.
>OBJECTIVE: the objective of this study was to assess the effects of
>increasing auditory acuity by providing hearing aids to subjects with
>dementia who have mild hearing loss. METHOD: subjects were screened for
>hearing impairment and fitted with a hearing aid according to standard
>clinical practice. Measures of cognition and psychiatric symptoms,
>activities of daily living, and burden on carers were made over 6 months.
>Hearing aid diaries were kept to record the acceptability of the hearing
>aids to the subjects. RESULTS: more than 10% of eligible subjects were
>excluded as removal of wax restored hearing. Subjects showed a decline in
>cognitive function, no change in behavioural or psychiatric symptoms over
>the study period. Forty-two percent of subjects showed an improvement on
>an independently rated measure of change. The hearing aids were well
>accepted. Both carers and subjects reported overall reduction in
>disability from hearing impairment. CONCLUSIONS: all patients with hearing
>impairment require thorough examination. The presence of dementia should
>not preclude assessment for a hearing aid as they are well tolerated and
>reduce disability caused by hearing impairment. Hearing aids do not
>improve cognitive function or reduce behavioural or psychiatric symptoms.
>There is evidence that patients improved on global measures of change.
>PMID: 12615563 [PubMed - indexed for MEDLINE]
>2: Lakartidningen. 2001 Jun 6;98(23):2802-6. Related Articles, Links
>[Presbyacusis--hearing loss in old age]
>[Article in Swedish]
>Horselkliniken, Karolinska sjukhuset/institutionen for klinisk
>neurovetenskap, Karolinska institutet, Stockholm. email@example.com
>Presbyacusis is a very common type of hearing loss, often having profound
>effects on the quality of life in old age. Since the number of elderly
>persons is increasing, the incidence of presbyacusis is also expected to
>increase in the future. Presbyacusis is caused by cochlear degeneration,
>most pronounced in the basal cochlear coil. The most common audiometric
>configuration is a gently sloping audiogram, above all affecting the high
>frequencies. Efforts to improve auditory communication in old age are
>important, and can be expected to result in improved quality of life for
>elderly persons and in more efficient use of public resources. The
>alleviation of age-related hearing handicap includes aural rehabilitation
>with hearing aid fitting and training programs, specially designed for
>elderly people. Hearing loss is often combined with other handicaps, such
>as dementia, immobility and poor vision. The synergistic effects of
>multiple handicaps can be extensive. Prevention is an issue which is both
>challenging and problematic. The most important preventive measure is
>noise reduction, which must start early in life and not shortly before
>retirement. Inner ear treatment programs, currently under development,
>might possibly be suitable for treatment of inner ear disorders in the
>future. Considerable gains can be achieved with respect to resources both
>human and economical through rehabilitation and suitable preventive
>PMID: 11462274 [PubMed - indexed for MEDLINE]
>3: Can J Psychiatry. 1999 May;44(4):393-4. Related Articles, Links
>Deafness mistaken for dementia.
>Jalbert M, Primeau F.
>PMID: 10332584 [PubMed - indexed for MEDLINE]
>4: West J Med. 1997 Oct;167(4):247-52. Related Articles, Links
>Hear ye? Hear ye! Successful auditory aging.
>Gates GA, Rees TS.
>Department of Otolaryngology-Head and Neck Surgery, University of
>Washington School of Medicine, Seattle 98195-7923, USA.
>Age-related hearing loss (presbycusis) is a multifactorial process that
>affects nearly all people in their senior years. Most cases are due to a
>loss of cochlear hair cell function and are well mediated by communication
>courtesy and modern amplification technology. Severe hearing loss is
>generally due to cochlear problems or age-related diseases and may require
>speech reading, assistive listening devices, and cochlear implants,
>depending on the degree of loss. Presbycusis may seriously impair
>communication and contribute to isolation, depression, and possibly
>dementia. Accurate diagnosis and prompt remediation are widely available
>but are frequently underused. Geriatric health care and well-being is
>enhanced by the detection and remediation of communication disorders.
>PMID: 9348755 [PubMed - indexed for MEDLINE]
>5: Biol Psychiatry. 1995 Nov 15;38(10):649-58. Related Articles, Links
>Age at onset of geriatric depression and sensorineural hearing deficits.
>Kalayam B, Meyers BS, Kakuma T, Alexopoulos GS, Young RC, Solomon S,
>Shotland R, Nambudiri D, Goldsmith D.
>Department of Psychiatry, Cornell University Medical College, New York, NY.
>Comorbidity of sensorineural hearing deficits and both depressive states
>and dementia in late life provided the rationale for this investigation.
>Cognitively intact geriatric major depressives (n = 43) were assessed for
>depressive symptoms, cognitive performance, and delusions while
>symptomatic, and following treatment, when audiometry was performed.
>Late-onset depressed patients (LOD) had more hearing deficits compared to
>early-onset depressives (EOD). Age at onset of depression was found to
>have a significant effect on Pure-Tone Thresholds for 0.5-4.0 kHz and on
>Word Recognition in Noise in the better ear (0.001 < p < 0.031; ANCOVA).
>Criteria for neural deficit were met more frequently in LODs compared to
>EODs, although this was attributable to the older age of LOD. Additional
>investigations can contribute to our understanding of the relationship
>between forms of hearing loss and both the course of geriatric depression
>and its relationship to dementia.
>PMID: 8555376 [PubMed - indexed for MEDLINE]
>6: Arch Neurol. 1995 Jun;52(6):626-34. Related Articles, Links
>Auditory dysfunction in aging and senile dementia of the Alzheimer's type.
>Gates GA, Karzon RK, Garcia P, Peterein J, Storandt M, Morris JC, Miller JP.
>Virginia Merrill Bloedel Hearing Research Center, Department of
>Otolaryngology-Head and Neck Surgery, University of Washington, Seattle,
>OBJECTIVE: To determine the prevalence and type of auditory dysfunction in
>older volunteer subjects with mild probable Alzheimer's disease (pAD).
>METHODS: Pure-tone thresholds, word recognition in quiet, Synthetic
>Sentence Identification with Ipsilateral Competing Message or
>Contralateral Competing Message, distortion-product otoacoustic emissions,
>and auditory brain-stem responses were done in 82 elderly volunteer
>subjects whose cognitive, psychologic, and neurologic status had been
>determined through annual testing in a research center. Based on clinical
>criteria and the Clinical Dementia Rating (CDR) scale, 40 subjects had
>been judged to be nondemented (CDR score, 0), and 42 had a clinical
>diagnosis of pAD, with 22 in the questionable (CDR score, 0.5) and 20 in
>the mild (CDR score, 1) categories. RESULTS: The mean age-adjusted
>pure-tone average thresholds (0.5, 1.0, and 2.0 kHz) were poorer in the
>subjects with pAD by 5.1 dB in the right ears and 6.1 dB in the left ears;
>these differences were not statistically significant. Word recognition in
>quiet did not differ by CDR category. The age-adjusted scores on the
>Synthetic Sentence Identification with Ipsilateral Competing Message or
>Contralateral Competing Message were significantly reduced in the subjects
>with mild pAD. Distortion-product otoacoustic emission amplitudes and
>auditory brain-stem response thresholds and latencies paralleled the
>pure-tone threshold results and did not differ across the CDR groups.
>CONCLUSIONS: Central auditory dysfunction was evident in subjects with
>even mild cases of pAD, whereas peripheral auditory function was not
>different from that in age-matched control subjects. Additional research
>is needed to delineate the mechanisms of central auditory dysfunction and
>to establish the sensitivity and specificity of auditory testing in
>subjects with Alzheimer's disease. We recommend auditory assessment,
>including Synthetic Sentence Identification with Ipsilateral Competing
>Message or Contralateral Competing Message, for older patients in general
>and in particular for those in whom dementia is suspected.
>PMID: 7763213 [PubMed - indexed for MEDLINE]
> > I just read the piece on Mead Killion's idea of inexpensive hearing aids.
> > Hearing aids are not just something to slap in your ears and off you go.
> > There are a myriad of considerations to take into account when not only
> > choosing the setting during the first fitting, but the follow up care.
> > This is largely due to the plasticity of the auditory system and the
> > absolute need for the Audiology, Dispensing, Manufacturing and other
> > related medical fields to go beyond hearing aids as a simple correction.
> > Auditory neuroscience has been my specialty for the last 6 1/2 years.
> > It's taken me a long time to amass the amount of journal articles (3400)
> > among multidisciplinary fields of medical science to be able to fit
> > successfully those patients that range from mild to severe hearing losses.
> > Considerations such as their current and past medical or developmental
> > history is of utmost importance if I am to be successful at fitting the
> > hearing aids during the first 6 months that match the initial auditory
> > system capability and to keep pace with the neurophysiological changes
> > that occur through stimulation and rehabilitation
> > For example, if I have a patient with panic and anxiety disorders and a
> > patient who is a professional musician, even though they may have the
> > exact same audiogram, their settings on the hearing aids will be
> > completely different including the type of hearing aid. The P and A will
> > be drastically below the expected settings and the PM will be above. This
> > is due to their specific neurophsyiology makeup that give substantial
> > control over his system in the musician and the lack of control in the
> > P&A. The neuroanatomical differences in musicians vs. non-musicians
> > have been established numerous times. With a 25% greater response to
> > piano harmonics than pure tones, I need to try to match the hearing aids
> > to musical harmonics instead of the pure tones we use during testing.
> > Additionally, the counselling that would go into encouraging and
> > maintaining use of the hearing aid is also going to markedly different.
> > An Alzheimer's patient and a Parkinson's patient's rehabilitation time is
> > going to be significantly longer than a normal healthy control due to the
> > depletion of Acetylcholine through the degenerative process of AD and the
> > anticholinergic medication of the PD patient. Acetylcholine is largely
> > responsible for auditory system plasticity during rehabilitation. A
> > decreased availability will extend the rehabilitation time and potentially
> > reduce the final recovery of function.
> > I could go on and on about the different parameters that make hearing aid
> > fittings difficult for so called "easy" mild hearing losses. But I won't.
> > Suffice it to say, if more University programs would concentrate on the
> > neuroscience end of central auditory processing and the degenerative
> > processes as a result of a hearing loss (which can begin at 20dBHL with
> > the loss of GABA receptors creating more spontaneous activity, less
> > temporal resolution, less frequency resolution, less spatial acoustics,
> > etc.) Mr. Killion, with all due respect to his position in Audiology would
> > not be so quick to relegate hearing aids to the "over the counter reading
> > glasses" genre.
> > Barbara Reynolds, M.S.
> > Clinical Audiologist FREE pop-up blocking with the new MSN Toolbar – get
> > it now!
>Ward R. Drennan, Ph. D.
>Kresge Hearing Research Institute
>Ann Arbor, MI 48109