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On the importance of having a good heart

Today I just though I'd draw your attention to an article ("Vascular Contributions to Neurodegeneration: Protocol of the COMPASS-ND Study"), led by my esteemed colleague and power-house Eric Smith (U. Calgary), about our estimating cerebrovascular health in participants to the COMPASS-ND cohort of the Canadian Consortium for Neurodegeneration and Aging. As you might expect, this component of brain health is closely linked to what happens elsewhere in the body - namely cardiovascular health.

The COMPASS-ND cohort is the biggest and most phenotypes observational study on Alzheimer's disease and the full spectrum of related disorders - from subjective to mild cognitive impairment, to other forms of dementia e.g. vascular, mixed, Lewy body and fronto-temporal cases. Apart from extensive clinical testing - clinical, cognitive, and behavioural - we also sample blood, saliva, and faeces in everyone, as well as cerebrospinal fluid (the latter in about 15% of the whole cohort).

An inclusion criteria to the study is to be able to be scanned using MRI. We use for this purpose the Canadian Dementia Imaging Protocol, the development of which was led by yours truly, alongside Eric and other colleagues from across Canada. Of specific interest in the protocol, and evidenced in the initial data from the article, was our emphasis on assessing cerebrovascular health - i.e. getting images of the state of vascular pathology in the brain. In that, the protocol was compliant with both the STRIVE and HARNESS position papers.

And it paid off. Contrary to other efforts - such as the well-known ADNI study - that attempt to create a study group as homogeneous as possible, the aim of the COMPASS-ND was to embrace real-world heterogeneity and so, it was not surprising but still interesting to see how much vascular pathology was present across participants in our cohort.

In fact, after reviewing the MRIs, the initial diagnostic changed to include a vascular component in at least 25% of cases (e.g. from Alzheimer's disease dementia to a mixed (Alzheimer's and vascular) dementia)(these results not shown in the article and are still preliminary, but hey, I thought they were really, really interesting).

These results lend further weight to the necessity of creating multi-factorial models and theories, and move away from the unicity of constructs such as the amyloid hypothesis. By embracing this complexity, we stand a better chance at understanding what is actually going on in Alzheimer's, a question which remains unanswered after a solid 40 years of intense research worldwide. Moreover, detecting cerebrovascular changes is of importance, as cardiovascular diseases are to some degree treatable.

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