Reacción a "Reactions: study associates hormone therapy for menopause with possible development of dementia "

[T]he study has strengths in utilising nationwide data it has available and their effort to try to differentiate between different types and duration of HRT use is admirable, well-needed and seems fairly robust. 

However, the study has fundamental limitations in its ability to interpret and understand the true underlying causal pathways of the observed association, as both the exposure (why you would be prescribed HRT in the first place, and why you would be prescribed certain types and duration of medication use) and the outcome (dementia diagnosis) have many things in common that influence them, and so this association may be artificial. 

For example, changes in sleep or mood are very common symptoms of menopause and reasons to seek out HRT; meanwhile we are starting to understand that sleep and mood may play an important role in in the expression and progression of dementia.  

The best way to understand whether HRT medication itself causes dementia comes from clinical trials, and to date, there is not enough evidence to support a direct link from the medication itself, and this new study alone should not change practice.  

What is clear from this study is that more research is warranted to understand the exacerbated risk of AD in women, including the role and patterns of HRT on diseases that cause dementia, but also to understand the wider context, encompassing menopausal symptoms, as well as life course and sociocultural influences that impact women in this transitional period of their life.