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Cataract removal and visual stimulation
may delay course of dementia in elderly patients
Stefanie Petrou-Binder MD
in Ludwigshafen, Germany
CATARACT surgery and other interventions which improve vision may
delay the course of dementia in at-risk elderly patients, German
researchers believe.
“Visual impairments occur frequently in people suffering from
senile dementia and they strengthen the cognitive impairment of
the disease. The root of the visual problem is often cataract,”
reported Siegfried Lehrl MD at the annual congress of the German-Speaking
Association for Intraocular Lens Implantation and Refractive Surgery
(DGII).
Dr Lehrl, a psychiatrist at the Erlangen-Nuremberg University’s
psychiatric clinic, reported that almost one third of the dementia
patients he evaluated as part of a retrospective trial had severe
visual impairments. He reported that these patients had much lower
cognitive test scores than dementia patients without visual impairments.
He evaluated the cases of 49 patients diagnosed with dementia or
suspicion of dementia seen at the university day clinic between
1991 and 1994. His re-evaluation of these patients included the
use of two cognitive functions tests, the Mini-Mental-Status-Examination
(MMSE) and the KAI test (Kurztest für Allgemeine Intelligenz).
Dr Lehrl and his team tested 37 elderly patients in need of nursing
care with the MMSE and KAI screening tools. The remaining 12 patients
were excluded because of concomitant disease including Parkinson’s
disease and stroke. The average age of the participating patients
was 78 years, with 64% female.
MMSE test scores
The MMSE test scores indicated moderate to severe levels of dementia.
The 10 patients with severe visual disturbances had statistically
significantly lower MMSE scores compared with the 27 patients who
did not have severe visual disturbances.
Eight of the 10 patients scored in the range indicating severe dementia.
Test scores among the patients without visual impairment reflected
more moderate levels of dementia.
The results of the KAI test, which assesses the speed of information
processing, tended to support the MMSE results. In some cases, patients
who were unable to perform the visual element of the KAI test because
of poor vision underwent an acoustic KAI subtest which assesses
attention span, he noted.
In fact, it was the patients who did not perform well on the standard
KAI test who were more likely to become candidates for permanent
nursing care. These patients also had the lower MSSE scores, he
said.
Dr Lehrl explained that severely impaired visual acuity influences
the progress of dementia in two ways. First, the visual disadvantage
these patients have may be mistaken for dementia, and secondly,
the degree of dementia is indeed worsened by impaired vision.
He said the prevalence of cataract in old age is high, and that
IOL implantation may offer these patients the chance to reduce the
symptoms of dementia.
This in turn could have a positive influence on reducing the high
costs associated with more than one million cases of senile dementia
requiring permanent nursing care in Germany today.
The MMSE is an achievement test used internationally to assess a
broad spectrum of cognitive function including orientation, attentiveness,
concentration, language and direct and indirect memory.
The test is predominantly based on problems which have to be dealt
with out loud, such as spelling the word ‘radio’ backwards,
or subtracting seven starting from 100 (93…86…79…).
Patients receive points for correct answers. The possible point
spread is zero to 30. Patients with 25 to 30 have no dementia. Those
with 22 to 24 have questionable dementia. Moderate dementia is noted
in patients who scored 16 to 21 points. Patients with strong dementia
score only eight to 15 points and those with severe dementia score
zero to seven.
The KAI test has both visual and auditory subtests and correlates
with the MMSE. The optical test measures the basic speed of information
processing. The physician reads off a row of random, unrelated,
1.0cm high letters quickly and in a low voice.
At the last letter, the physician repeats the row and asks the patient
to repeat what he can, thereby ascertaining his limits. The auditory
test assesses the patient’s attention span vocally.
Friedrich Lehrl MD
Clinic for Psychiatry and Psychotherapy,
Erlangen-Nuremberg University, Germany
Email: siegfried.lehrl@psych.imed.uni-erlangen.de
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