Saturday, March 14, 2015

Speech Markers of Alzheimer's Disease Progression

Bill Yates
Brain Posts
Posted 1st November 2013

Sensitive, reliable and inexpensive markers of disease progression in Alzheimer's disease are needed.

It is known that language and speech domains are impaired with Alzeimer's disease.

What is not known is whether speech performance can be used in the diagnosis and monitoring of progression in Alzheimer's disease (AD).

A recent case series published in the journal Brain supports the potential for expanded use of speech assessment in AD.

Ahmed and colleagues reported their findings in a group of 15 patients.  All patients had been assessed longitudinally, died during the course of follow up and had post-mortem confirmation of AD.

Subjects completed a comprehensive battery of neuropsychological assessments during their period of observation.

One neuropsychological assessment of speech in this study was a test called the Cookie Theft description from the Boston Diagnostic Aphasia Examination.  In this task, a series of pictures is shown to subjects who then are asked to tell the examiner everything they saw in the pictures.

The vocal production in this task can be recorded and the speech can be graded on a group of language domains including: speech production, syntax complexity, lexicon content and fluency errors.

The primary findings from these subjects followed through the course of AD included:
  • Two thirds of subjects showed abnormalities in connected speech when classified as mild cognitive impairment prior to meeting clinical criteria for AD
  • There was a linear progression of speech deficits as subjects progressed from mild to moderate to severe deficits
  • The speech/language deficit impaired with disease progression included syntax complexity, semantic content and lexicon content
The authors conclude from this case series that language assessment may prove to be simple but valuable tool in distinguishing effects of normal brain aging from AD. Additionally, they note careful speech and language assessment may serve to aid in the longitudinal monitoring of the severity of the disease and potentially even be used as an outcome measure in clinical drug trials.

The take home message for family members would be that speech and language is commonly impaired in AD.  Reduction in the amount and complexity of speech to family members may be one clue to the need for clinical assessment.

The finding of the current study will need to be replicated in separate cohorts of patients. This will not be easy as collecting longitudinal data on AD subjects early and throughout progression is difficult and time consuming.

Additionally, research will need to identify specific marginal effects of language assessment above other commonly used AD assessment tools (MMSE).

Readers with more interest in this research can access the free full-text manuscript by clicking on the PMID link below.

Follow the author on Twitter: @WRY999

Photo of sandhill crane sculpture at the Brookfield Zoo is from the author's files.

Ahmed S, Haigh AM, de Jager CA, & Garrard P (2013). Connected speech as a marker of disease progression in autopsy-proven Alzheimer's disease. Brain : a journal of neurology PMID: 24142144.

See the original article:

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