however it is possible that although coded as the underlying cause some of these deaths were precipitated by another condition such as influenza or cvd ho and hendi for example in england and wales over a third of all deaths with an underlying cause of dementia or alzheimer s disease are reported to also have a respiratory disease mentioned on the death certificate ons a although the reasons for the seasonal pattern in deaths from dementia and alzheimers disease are not clear it may be related to the greater vulnerability of people with these conditions to respiratory diseases