Risk factors differ for early and delayed dementia after ICH

By Lucy Piper

Acute haematoma parameters predict the onset of dementia in the first 6 months after intracerebral haemorrhage (ICH), but not that of delayed dementia, report researchers.

"These findings support the hypothesis that different mechanisms underlie cognitive impairment after ICH depending on temporal dynamics", they say.

Among 738 ICH patients aged an average of 74.3 years, 279 (37.8%) developed dementia at some point over the median 47.4 months of follow-up, with the incidence of early and delayed onset very similar, at 140 and 139 patients, respectively.

The researchers, led by Alessandro Biffi (Massachusetts General Hospital, Boston, USA), estimated the yearly incidence of dementia to be 5.8%.

Results of multivariable analyses showed that every 10 mL increase in haematoma size increased the risk of early dementia by 47%, while a lobar location of ICH increased the risk by 104%.

Carrying at least one copy of the apolipoprotein E (APOE) ε2 gene variant was also found to be a significant risk factor for early dementia, increasing the risk by 69% among a subset of 257 patients who had APOE status and magnetic resonance imaging data available.

By contrast, for delayed onset of dementia, significant risk factors were diagnosis of a mood disorder and increasing white matter disease on computed tomography, which increased the risk by 29% and 70%, respectively, while attaining at least 10 years of education reduced the risk by 40%.

Additional risk factors identified in the subsample of patients included being a carrier of at least one APOE ε4 variant copy and increasing burden of lobar cerebral microbleeds, with risk increases of 112% and 78%, respectively.

The only risk factor predicting early and delayed dementia was advancing age at index ICH, the team notes in JAMA Neurology.

"These findings are of immediate clinical relevance to health care professionals and patients who have experienced ICH", the researchers highlight.

They continue: "Assuming replication of our findings in future studies, adequate communication of the risk of cognitive decline (especially beyond the immediate period after ICH) will represent a critical issue for physicians, their patients who have experienced ICH, and patients' family and caregivers."

In a related editorial, Rebecca Gottesman (Johns Hopkins University, Baltimore, Maryland, USA) says that the study provides "valuable insight" and the frequency of dementia reported "emphasizes that it may be helpful to routinely incorporate questions about cognitive status and functional recovery after ICH."

But she also points out that the underlying process remains unclear and dementia after ICH should be considered as both "a potential cause and effect".

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