neurotaylor

Dementia research update

Following a request on Twitter, this post summarises some of the major research developments in dementia science between the time when my book The Fragile Brain was submitted (March 2016) and its publication last month (November 2016).

For a more general study of growing older, there’s an OUP VSI (Very Short Introduction) on ageing just out, though I haven’t had a chance to look at it yet.

Treatments

The big clinical news is surely the failure of the solanezumab trial, based on the amyloid cascade hypothesis. Some researchers reacted by giving reasons why the failure didn’t kill the hypothesis; others remarked that you can’t kill something that’s already dead. Apart from its implications for research, this is another setback for patients desperate for good news.

Lifestyle

Good news may yet arrive from treatment trials, but we got some by another route this year, courtesy of big epidemiological studies such as Langa et al. and Matthews et al.. These support the idea that dementia rates may be slowing, at least in Western countries like the UK. That suggests that the lifestyle changes people have made so far may be having an effect.

These changes are sizeable. In the UK, for instance, smoking has dropped from 46% to 19% of adults since 1974, according to the Office for National Statistics. If so much change is possible, perhaps there’s hope for other risk factors like overeating, pollution, and physical inactivity. It would help if governments would take them more seriously, though there are hints of progress here too, such as the new UK sugar tax. Countries in which smoking rates remain high and diets are becoming more Western are storing up trouble – and expense – for future generations.

Research

In research, one obvious change (certainly since I began work on The Fragile Brain) is that neuroimmunology – and the broader acceptance that blood factors can and do affect the brain far more than previously thought – is now mainstream. For example, the journal Neuropsychopharmacology has just issued a table of contents on the topic (Volume 42, Issue 1, January 2017). Emphasis on diabetes and depression as risk factors has increased accordingly, given the importance of inflammation in these disorders. Research into the gut and microbiome, and their potential impact on ageing brains, is also gathering pace (e.g. Sampson et al.).

Complementing this is the growing understanding that the brain’s non-neuronal cells – such as astrocytes, microglia, oligodendrocytes, pericytes and endothelial cells – really matter for neurons’ and synapses’ wellbeing. These formerly neglected cells, and the vascular system, are vital for keeping the brain healthy into old age (see e.g. Ma et al.).

There has also been progress on the notoriously difficult problem of the amyloid peptides’ structures (see for example Riek et al., Xu et al., Wälti et al., Eisenberg et al., and more).

Work on prions, and on the implication that amyloid too may be infectious, also proceeds: see for example the recent Nature Insight review by (of course) John Collinge et al. The other papers in that collection are also well worth a look. For example, the fascinating piece by Rebecca Canter and colleagues looks at neural circuitry failures in neurodegeneration.

Efforts continue to make the impact of new methods, such as organoids, ‘omics’ and neuroimaging, felt in neurodegeneration research, and to organise the masses of data they produce (see e.g. Rollo et al.). It’s becoming clearer that lipids, and the cell membrane, are more important players than previously realised, which potentially opens up new treatment and dietary avenues for research. For proteins, the importance of variants in genes other than ApoE, such as TREM2, is becoming more apparent, and ApoE studies are also branching out.

This is a brief summary of recent developments; there’s much more than I’ve covered here. It’s a fast-moving field, and 2017 should bring plenty of advances in basic research. And treatments? Well, here’s hoping. Perhaps some of the other antibody trials, or alternative approaches such as insulin, will produce encouraging results.

Whatever happens in 2017, in dementia research and elsewhere, I wish you a successful new year.