Memory complaints link to stroke risk for the highly educated

Forgetting why you have gone into a room or misplacing your keys is frustrating, but new research suggests that these lapses in memory could signal more than just absent-mindedness. A new study has found that highly educated people with memory complaints could have an increased risk for stroke.

Previous research found an association between memory complaints and Alzheimer's disease among the highly educated.

The study, published in Stroke, followed a cohort of participants who had completed questionnaires and undergone mental examination, looking for signs of incident stroke.

Studies have shown how stroke causes memory complaints," says the research team at Erasmus University Rotterdam in the Netherlands. 

"Given the shared underlying vascular pathology, we posed the reverse question: 'Do memory complaints indicate an increased risk of strokes?'"

Strokes are caused by the blocking of blood vessels to the brain by clots (ischemic stroke) or a blood vessel bursting (hemorrhagic stroke). Preventing blood vessels transporting oxygen and nutrients to the brain, strokes cause damage to the organ and kill brain cells.

According to the Centers for Disease Control and Prevention (CDC), strokes are the cause of almost 130,000 American deaths each year - 1 in every 19 deaths. Every year, more than 795,000 people in the US have strokes, at an estimated cost to the country of $36.5 billion.

It is important that stroke treatment begins as soon as possible, as it greatly increases the chances of survival. Research into potential risk factors for stroke will no doubt improve the odds of stroke patients being treated quickly and efficiently.

People with memory complaints and higher education had 39% higher risk of stroke

For the study, the authors followed 9,152 participants aged 55 or older from the Rotterdam Study - a large population-based cohort study that began in 1990 and was expanded upon in 2000.

First, the participants each completed a subjective memory complaints questionnaire before taking a Mini-Mental State Examination (MMSE), a test to determine the presence of cognitive impairment.

The participants were then followed-up until 2012. During this period, 1,134 strokes were recorded: 663 ischemic strokes, 99 hemorrhagic strokes and 372 that were unspecified.

An association was found between subjective memory complaints and a higher risk of stroke. Registering a high score in the MMSE, however, indicating normal brain function, was not associated with an increased stroke risk.

The researchers then conducted further analysis of their findings. "Given the role of education in revealing subjective memory complaints, we investigated the same association but in three separate groups: low education, medium education and high education," explains Dr. Ikram.

Levels of education were categorized as follows:

• Low education - primary education only
• Intermediate education - primary education with certain additional education, or general secondary education
• High education - vocational education or university training.

People with memory complaints were found to have a 39% higher risk of stroke if they had a higher level of education.

Potential new targets for risk assessment

If in future research the researchers can confirm this, then they would like to assess whether people who complain about changes in their memory should be considered primary targets for further risk assessment and prevention of stroke.

The authors believe that their finding could be explained by highly educated people being more likely to notice changes in their cognitive performance than less educated people, making memory complaints a more suitable measure of cerebrovascular degeneration in this population.

Future research will need to include more racially diverse groups, as over 95% of the study's participants were white people living in one particular area of Rotterdam. MRI findings should also be included so that the evidence of small vessel disease - an underlying factor in the relationship between stroke and memory complaints - can be fully explored.

References:

1. Subjective Memory Complaints and the Risk of Stroke, Ayesha Sajjad, et al., Stroke, doi: 10.1161/STROKEAHA.114.006616, published online 11 December 2014, abstract.
2. American Heart Association news release, accessed 11 December 2014 via AlphaGalileo.
3. Additional source: CDC Stroke facts, accessed 11 December 2014.