News From the 59th Annual Meeting of the American Academy of Neurology, Boston, April 28 - May 5, 2007

Personality Traits Early Clue to Distinguishing LBD From AD. Lewy body dementia (LBD) is often difficult to distinguish from Alzheimer disease (AD) but subtleties in symptoms provide clues to the differential diagnosis. With the aim of identifying clinical markers that would aid in the early differential diagnosis of LBD and AD, a team led by James E. Galvin, MD, MPH, assistant professor of neurology, anatomy, and neurobiology at Washington University School of Medicine in St Louis conducted a longitudinal study. The research involved a group of patients (mean age, 77.6 years) in whom either LBD (n = 125) or AD (n = 125) had been diagnosed. An additional 34 healthy controls were included in the study. Intimates of the studied patients were annually interviewed about changes in the patients' personalities, interests, and drives in accordance with the Blessed Dementia Rating Scale (BDRS). The study was intended to follow patients until death, when autopsy data could be retrieved.

In all, a mean of 4.8 (range, 1 to 14) evaluations and interviews were conducted. Galvin and colleagues determined that patients with LBD were more likely than patients with AD to display diminished emotional responsiveness, apathy, and purposeless hyperactivity and to lose interest in hobbies.

The team concluded that incorporating a simple personality trait rating scale such as the BDRS in the diagnostic workup is useful in distinguishing LBD from AD.

Photophobia is a Differential in the Diagnosis of Tauopathies. Photophobia may be a key feature that helps distinguish progressive supranuclear palsy (PSP) from corticobasal degeneration syndrome (CBDS), according to a team from the Mayo Clinic. In looking at the prevalence of visual hallucinations, REM sleep behavior disorder, and photophobia in 21 patients in whom PSP (n = 10) or CBDS (n = 11) was diagnosed, Keith A. Josephs, MD, assistant professor of neurology, and junior colleague Alex D. Cooper, MD, found that photophobia was strongly associated with PSP.

All patients had received a diagnosis of either PSP or CBDS by a single movement disorders specialist between years 2003 and 2006. Median age of disease onset was 66 years (range, 59 to 77) for patients with PSP and 65 years (range, 49 to 81) for patients with CBDS. All 10 (100%) of the patients with PSP experienced photophobia while only 2 (18%) of the patients with CBDS experienced this symptom. Incidence of visual hallucinations and REM sleep behavior disorder were infrequent (5% incidence for each symptom), and these symptoms were not more commonly seen in one patient group than another.

Because photophobia appears to be a distinguishing symptom of PSP, its presence can be considered a factor in the differential diagnosis of PSP and CBDS, the Mayo investigators concluded.

Tau Marker for PSP Nigh. Because tau levels vary widely in cerebrospinal fluid (CSF), they have not been considered useful in differentiating neurodegenerative disorders, but a multicenter team of Italian researchers that scrutinized tau forms has identified a pattern unique to progressive supranuclear palsy (PSP). The team evaluated total tau and phospho-tau CSF levels in 26 healthy persons (controls) and 78 patients with neurodegenerative disorders such as PSP, Alzheimer disease, frontotemporal dementia, cortico- basal degeneration syndrome, Parkinson disease, and Lewy body dementia. The study participants also underwent clinical and neuropsychological testing as well as MRI.

In ferreting out different tau epitopes, the researchers identified an extended (55 kDa) and a truncated (33 kDa) form. They measured the ratio of these forms in the CSF and found that the ratio of truncated to extended forms was significantly decreased in patients with PSP compared with controls and patients with other neurodegenerative diseases. The researchers concluded that their findings may be extrapolated into identification of a diagnostic marker for PSP.

The respective citations for the meeting presentations that correspond with these news briefs are as follows:

• alvin J, Malcom H, Johnson DK, Morris J. Personality traits distinguishing dementia with Lewy bodies from Alzheimer disease. Neurology. 2007;68(suppl 1): A13.
• Cooper AD, Josephs KA. Photophobia, visual hallucinations, and REM sleep behavior disorder in patients with progressive supranuclear palsy and cortico- basal syndrome: a prospective study. Neurology. 2007; 68(suppl 1):A48.
• Padovani A, Borroni B, Gardoni F, et al. Pattern of tau forms in CSF: a new marker for progressive supra- nuclear palsy. Neurology. 2007;68(suppl 1):A235.