News Roundup: Alzheimer Disease

There’s a lot going on in neurological research on Alzheimer disease (AD). β-amyloid affects memory, but it may do so by impacting sleep. Researchers have measured a specific link to β-amyloid in the prefrontal cortex, and its impact on slow wave sleep could affect memory consolidation in the hippocampus. Neuroanatomy will never be the same, since scientists recently discovered vessels linking the immune and nervous systems directly. Exciting new research directions based on this finding will certainly result. Symptoms of AD could be different depending on age. Younger AD patients may actually have more problems with behavior and non-memory tasks, which may change AD treatments to be based on age.

Explore researchers' findings on the following pages.

β-amyloid Disrupts Sleep in AD

• β-amyloid, the pathologically misfolded protein found in AD, is known to disturb non-rapid eye movement (NREM) sleep.

• Scientists at the University of California used neuroimaging to study 26 cognitively healthy volunteers, aged 65 to 81, to determine how much β-amyloid had built up in their brains, and its associations with sleep quality.

• Researchers found that increases in β-amyloid deposits, specifically in the medial prefrontal cortex (mPFC), correspond with increases in NREM sleep disruption.

• β-amyloid in the mPFC affected hippocampal memory consolidation (measured by a recall task) through reductions in mPFC NREM slow wave sleep.

• Sleep disruption in AD, specifically through mPFC connections to the hippocampus, could be one factor impacting memory in AD.

Source: Mander BA, et al. β-amyloid disrupts human NREM slow waves and related hippocampus-dependent memory consolidation. Nat Neurosci. Published online 1 June 2015.

New Nervous System – Immune System Link Could Revolutionize Neurology

• Scientists at the University of Virginia studied the meninges of mice to find undiscovered lymphatic vessels lining the dural sinuses.

• The newly-found structures link the nervous system and immune system by transporting fluid and immune cells from the cerebrospinal fluid to cervical lymph nodes.

• The finding revolutionizes what is known about brain anatomy and could provide new perspectives for the treatment of immune system and nervous system diseases, such as AD.

Source: Louveau A. Structural and functional features of central nervous system lymphatic vessels. Nature. Published online 1 June 2015.

AD First Symptoms Are Age Dependent: Evidence from the NACC Dataset

• Alzheimer’s disease symptoms may be different in people of different ages.

• Researchers in London studied 7815 patients from the National Alzheimer Coordinating Center database to examine the association between age and first cognitive or behavioral symptoms.

• Non-memory cognitive symptoms were more common in younger AD patients, such as language or problem-solving deficits.

• More behavioral symptoms occurred at younger ages as well.

• The study could have implications for treatments for AD based on age.

Source: Barnes J, et al. Alzheimer's disease first symptoms are age dependent: Evidence from the NACC dataset. Alzheimer Dement. In press.

Take-home points

• β-amyloid disrupts sleep and this may be one way it impacts memory in AD.

• A new immune system – nervous system link revolutionizes what is known about brain anatomy.

• People with AD have different symptoms depending on their age.