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Decreases in Stroke-Related Dementia Result from Smaller Memory Decrements

Declines in stroke-associated dementia may be due to a reduction in memory deficits occurring immediately after stroke onset, according to a cohort study published on March 16 in the journal Stroke.

“Consistent with recent trends observed in the Framingham Study, we observed improvements in cognitive functioning after stroke in recent years. However, we found that improvements in poststroke memory functioning were driven primarily by lessening of immediate memory deficits at the time of stroke onset, not differences in memory decline around stroke onset," wrote Chloe W. Eng, MSPH, of the University of California San Francisco, and colleagues.

The study authors found, however, that pre-stroke memory functioning for people who had a stroke had improved in recent years compared with earlier periods. And they attributed that, in part, to the fact that “determinants of stroke are less strongly associated with memory than in the past," adding, “Recent decreases in stroke-related dementia are also likely partially attributable to smaller memory decrements in the immediate aftermath of stroke."

These data add to the current understanding of stroke-associated decline by considering possible trends in the association between cognition and stroke across nearly 20 years, the researchers noted.

The researchers assessed a nationally representative cohort and looked at evidence on temporal trends in memory change associated with incident stroke.

The study authors assessed 2,434 participants with a first stroke, of which 590 were fatal, and 1,844 were nonfatal. At baseline, mean age was 66.3 years in epoch 1, 67.1 years in epoch 2,  and 66.5 years in epoch 3.

They evaluated adults age 50 years and older from the Health and Retirement Study across six-year successive epochs from 1998 to 2016. Participants were selected from six-year epochs and at baseline were stroke-free.

They used demographic-adjusted linear regression models to compare yearly rates of change in a composite z-standardized memory score.

The findings indicate that crude stroke incidence rates declined from 8.5 per 1,000 person-years in epoch 1 to 6.8 per 1,000 person-years in epoch 3. Moreover, the rates of memory change prior to and after stroke onset were similar across epochs.​

Notably, memory decrement immediately following stroke onset attenuated from −0.37 points in epoch 1 to −0.26 points in epoch 2 and −0.25 points in epoch 3 (pvalue for linear trend=0.02).

Limitations of the study include the inability to differentiate between stroke subtypes, that the study relied on self-reported stroke status, and inadequate information to assess potential mediation of secular trends by comorbidities like depression and vascular risk factors, the researchers noted.

Even though improvements in patient care for stroke survivors may account for trends in poststroke memory outcomes, future studies should focus on direct measures of quality of care and other potential mediators, the authors noted.Future studies may consider the impact of specific changes in stroke care during this study period to further address possible underlying mechanisms behind these observed trends," they concluded.


Eng did not report any disclosures.

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Eng CW, Mayeda ER, et al. Temporal trends in stroke-related memory change: Results from a US national cohort 1998–2016. Stroke 2021; Epub 2021 March 16.