DLB fluctuations: specific features that reliably differentiate DLB from AD and normal aging.

Area of Science:

• Neurology
• Gerontology
• Psychiatry

Background:

• Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are common neurodegenerative disorders.
• Distinguishing between DLB and AD is crucial for appropriate patient management and care.
• Fluctuations in attention and arousal are characteristic of DLB but require clear definition for diagnostic utility.

Purpose of the Study:

• To investigate specific features of fluctuations that can differentiate DLB from AD and normal aging.
• To establish the reliability and validity of informant-reported fluctuation symptoms in diagnosing DLB.

Main Methods:

• A cohort of 200 cognitively normal elderly individuals, 70 DLB patients, and 70 AD patients were studied.
• Collateral informants completed a 19-item questionnaire assessing symptoms of fluctuations and delirium.
• Statistical analysis was performed to identify features distinguishing the groups.

Main Results:

• Four key fluctuation characteristics differentiated AD from DLB: daytime drowsiness, prolonged daytime sleep, long staring spells, and disorganized speech.
• The presence of three or four of these features occurred in 63% of DLB patients versus 12% of AD patients and 0.5% of controls.
• Informant reports of these features showed high positive predictive value (83%) for DLB diagnosis against AD.

Conclusions:

• Disturbed arousal and disorganized speech are specific fluctuation aspects that reliably distinguish DLB from AD and normal aging.
• Informant-reported symptoms provide a valuable tool for differentiating DLB in clinical settings.
• These findings enhance the diagnostic criteria for DLB, particularly in differentiating it from AD.