NHS Choices have produced two good reviews or recent studies widely reported in the news.
They looked at a recent study investigating the use of self-reported cognitive activity in older adults. The study had a longitudinal design and a reasonable sample size (n=1157). The study showed a positive association between cognitive activity and delayed onset of dementia but was also associated with a more rapid rate of cognitive decline after onset of dementia. There were various interpretations of these results but the authors of the review point out that the results may have been influenced by a number of confounding factors and that replication with adjustment for confounders is needed before firmer conclusions can be drawn.
The other was a double-blind study published in PLOS-One. The NHS Choices detailed coverage is here. Essentially they took a relatively small group of people with mild cognitive impairment and randomised them to either a combination of high dose Vitamin B12, B6 and folic acid or else placebo. The subjects underwent an MRI scan of the head on entry to the study and two years later. They found that there was a 30% reduction in the rate of cerebral atrophy in the group on the high dose vitamin therapy. There were a few limitations however. Firstly there is the sample size – they have 168 people included in the final analysis. The second point is that the actual shrinkage is quite small – 0.76% versus 1.08% in the placebo group and over a relatively short time period (2 years) it is difficult to determine the significance of this. For instance, one of the most significant predictors of conversion from one form of MCI – amnestic MCI to Alzheimer’s Disease is the volume of the hippocampus rather than the cerebral volume. Another point is that we don’t know which people in the group were converting from MCI to dementia and the study wasn’t designed to detect changes in cognition between the groups. Still the result is interesting and they add some supportive evidence for the effect being mediated by homocysteine levels although as with the above study replication is needed with a slightly different design to address the above issues.
One small study showed evidence of hypoperfusion in the frontal lobes and hyperperfusion in the parietal lobe in FrontoTemporal Lobar Degeneration and a reversal of these findings in people with Alzheimer’s Disease. An open access systematic review of non-pharmacological interventions in dementia has been published here – the researchers find a good evidence base to support various interventions but depending on the outcome measures used. The authors of one paper have produced a mathematic model of Alzheimer’s Disease progression using ADAS-Cog scores as the dependent variable and basing their results on data from the Alzheimer’s Disease Neuroimaging Initiative. In a moderately sized prospective study with an albeit short follow-up period of 1.5 years, people with incident Alzheimer’s Disease who engaged in physical activity experienced significantly lower mortality than those who were inactive even after controlling for confounders. There wasn’t an assocation with rate of cognitive decline although there is other data which supports such a relationship. Anosognosia for amnesia was found in people with Alzheimer’s Disease but not mild cognitive impairment in this small study.
Mind Hacks has another interesting Spike Activity instalment.
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