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 Visual impairments: DLB vs. PCA 
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Joined: Fri Aug 11, 2006 1:46 pm
Posts: 4811
Location: SF Bay Area (Northern CA)
Post Visual impairments: DLB vs. PCA
One person in our local support group was first diagnosed with CBD (corticobasal degeneration) and, later, PCA (posterior cortical atrophy). That's the extent of my knowledge on PCA.

In the abstract below, PCA is described as the "visual variant of Alzheimer's Disease." This UK research compares 10 patients with possible or probable DLB, 9 patients with PCA, and 20 healthy controls on four visual tasks.

The findings were: "DLB patients did not differ from controls in low level visual functions of visual acuity and line orientation... However, higher level visual functions of contour integration...and the most complex task of object rotation...were impaired in DLB. In contrast, PCA patients were impaired in all tasks..."

It sounds like the "higher level visual functions" have to do with visuospatial deficits.

I've copied the abstract below.


Neuropsychology. 2010 Jan;24(1):35-48.

Visual impairments in dementia with Lewy bodies and posterior cortical atrophy.

Metzler-Baddeley C, Baddeley RJ, Lovell PG, Laffan A, Jones RW.

Research Institute for the Care of Older People (RICE), The RICE Centre, Royal United Hospital, Bath, BA1 3NG, United Kingdom.

Dementia with Lewy bodies (DLB) and Posterior Cortical Atrophy (PCA), the visual variant of Alzheimer's disease, are neurodegenerative diseases that present with progressive deterioration in visual perception. However, little is known about the precise nature underlying the complex visual deficits associated with both conditions.

The present study compared DLB, PCA, and healthy control participants, in four visual tasks designed to measure the efficiency of the visual system at different levels of processing. In ascending order of complexity there were tasks of visual acuity, line orientation, contour integration, and rotated object comparison.

DLB patients did not differ from controls in low level visual functions of visual acuity and line orientation, suggesting that early visual processing areas including V1 were relatively preserved, consistent with pathology evidence (Yamamoto et al., 2006).

However, higher level visual functions of contour integration, mediated by extrastriatal areas, and the most complex task of object rotation, relying on processing within inferior temporal (IT), parietal, and frontal cortices, were impaired in DLB.

In contrast, PCA patients were impaired in all tasks, consistent with evidence of widespread pathology within occipital and parietal areas in PCA. The latter suggests that both lower and higher level visual impairments contribute to the complex visual symptoms associated with PCA.

PubMed ID#: 20063945 (see for this abstract only)

Wed Jan 13, 2010 11:28 pm

Joined: Wed Dec 30, 2009 1:46 pm
Posts: 3213
Location: WA
That's very interesting, Robin! Now I'm going to have to research PCA! Do neurologists ever read these articles? [Just kidding--sort of!] Line orientation deficit was one of the first things I noticed with my husband. I know nothing abaout PCA, but I'll be looking it up! Thank you for posting these findings.

Thu Jan 14, 2010 12:52 pm

Joined: Tue Dec 01, 2009 5:04 am
Posts: 14
Location: New Zealand
Post LBD Research
Thanks Robin for that posting. My husband also has line problems when reading - blames the glasses, etc. It seems there are two problems, understanding what he's reading as well as the above. The frustrations of not being able to follow a paragraph through nad keep track of a story is immense.
I appreciate all these pieces of a complex jigsaw that you bringto our notice.

Fri Jan 15, 2010 4:31 am
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Joined: Thu Sep 10, 2009 2:29 pm
Posts: 68
Location: Marco Island, FL
Thanks, Robin. Still not sure I understand, but will copy and take to both the neurologist and the opthamologist to be sure they've seen it.


"It's not what you look at that matters, it's what you see.".....Thoreau

Fri Jan 15, 2010 9:01 am

Joined: Fri Jan 15, 2010 9:33 pm
Posts: 3441
Location: Vermont
I'm wondering if this is one of the reasons my dad can no longer read his 4 newspapers a day, which he was able to do just before Thanksgiving..... hmmmmm.......

Thu Jan 28, 2010 8:38 pm
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