Yesterday we discussed the topic of subtype diagnosis in the #demphd chat, which actually gave me some good ideas for some of my PhD chapters in which I compare everyday functioning profiles (IADLs) between Alzheimer’s and other types of dementia. But let’s move back to the beginning.
Most non-researchers or non-clinicians might confuse dementia and Alzheimer’s disease, not realising that the latter is just one form of dementia. So, here a little diagramme of some of the most prevalent subtypes:
As I said, there are other dementia subtypes! Take Alcohol-related dementia for example! I haven’t heard of it until quite recently! So to catch up with the latest research, I read this paper by Ridley and colleagues (2013) , a nice read for such a small subtype.
Speaking of prevalence rates of subtypes, one of the first question we were discussing in yesterday’s chat was on the prevalence rates of different subtypes. Yes, Alzheimer’s disease is the most prevalent form. But how common is DLB or vascular dementia? One of the prevalence factors the Alzheimer’s Society report Dementia: An Update discusses is that there are 40,000 people with early-onset dementia in the UK (that is, an onset before the age of 65). And according to the report, 17 percent of people with dementia have vascular dementia, whilst different forms of FTD only affect 2 percent of all people with dementia . Check out their nice infographic to that.
But as we were discussing, a 100 percent correct diagnosis can only really be made post-mortem, and there can be many cases of misdiagnosis. This is because symptom patterns of different dementia forms can overlap, so that it can be difficult to rule out certain subtypes.
The issue of a diagnosis of mild cognitive impairment was also raised. Can MCI truly be diagnosed, or is it merely heightened levels of cognitive deficits compared to the majority of older adults? It is a good question, since many people with a diagnosis of MCI do not continue to develop dementia. In the newest edition of the Diagnostic Statistical Manual (Edition 5), MCI has been newly classified under ‘mild neurocognitive disorder’ . If you are equally skeptical about MCI or just want to find out more, I’d suggest this recent review by Sachs-Ericsson and Blazer .
Taking into account the less common forms of dementia, it is difficult to recruit sufficient numbers for a study if you indeed decide to focus on specific subtypes. Some of us just recruit any type of dementia, as it depends on the research focus. Others however only focus on specific subtypes. As @RionaMcArdle pointed out, Newcastle seems to be the hub for DLB research, a rare form of dementia already, which must make it increasingly difficult to recruit people with this subtype!
All in all, it was a really helpful discussion for some of my write up. Plus, it was good to see some new faces, showing how #demphd is continuously growing! Welcome to @tshakey @shivoconnor @kim_neurosci @dengmaohui 🙂
Don’t miss the next chat on #publishing on May 5th!