Cognitive impairment may have doubled in the last decade

• Researchers investigated the incidence of memory concerns and mild cognitive impairment over 10 years among United Kingdom healthcare providers.
• They found that while memory concerns have remained stable, reports of cognitive impairment more than doubled between 2009 and 2018.
• They say this is likely due to a series of healthcare strategies to better identify and care for dementia in the U.K.

Dementia is characterized by a gradual deterioration in cognitive function, impacting memory, judgment, language, and other cognitive abilities.Over 55 million people live with dementia worldwide, and there are around 10 million new cases per year.

Initial concerns that point to dementia include subjective memory concerns (SMC) — when no clear impairment is found from psychometric testing, and mild cognitive impairment (MCI) — when there is objective evidence of decline.Both SMC and MCI increase dementia risk.

Until now, few studies had examined people who present symptoms of SMC and MCI to healthcare providers, and even fewer have explored their prognoses.

Recently, researchers from University College London examined records of SMI and MCI and their progression into dementia.

They found that at a 3-year follow-up, 45.5% of those with SMC and 51.7% of those with MCI received a dementia diagnosis.

They also found that rates of SMC and MCI as recorded by healthcare providers are lower than those reported in community surveys, suggesting that a minority of people who experience memory loss consult their general practitioner (GP) and have it recorded.

“Given the increased understanding of the importance of cognitive concerns over the past decade, and how this may signify incipient dementia, it is likely that the increase in recording of cognitive decline is a result of doctors’ better understanding of the need for more detailed assessment of objective cognitive function,” Yen Ying Lim, Ph.D., associate professor at Monash University, not involved in the study, told MNT.

The study was published in Clinical Epidemiology.

Data analysis

The researchers used the IQVIA medical research database, which collects over 18 million anonymized patient records from over 790 U.K. primary care facilities.

They used data from 1,310,838 individuals with memory concerns and 1,348,796 individuals with cognitive decline. The people were between 65 and 99 years old and contributed data to the database between January 2009 and December 2018.

Data included diagnostic records of SMC, MCI, and dementia, alongside covariates including age, sex, and social deprivation.

The researchers noted that SMC reports remained stable over time and affected 4.3% of individuals. However, they increased with age from 3.66 cases per 1,000 people among those aged 65–69 to 17.89 cases per 1,000 between 80 and 99 years old.

They also noted that females and those with higher levels of social deprivation were more likely to record SMC.

Over the study period, 1.1% of the participants reported MCI, with 38.4% of these people also reporting SMC.

Unlike SMC, MCI reports increased over time, from 1.32 cases per 1,000 people in 2009 to 3.5 cases per 1,000 people in 2018.

Rates of MCI also increased with age from 0.65 cases per 1,000 people aged 65–69 to 5.17 cases per 1,000 among those aged 80–99.

Identification strategies

To explain the stable rate of SMC records alongside the increase in those for MCI, the researchers noted that the National Healthcare System (NHS) in the U.K. published three national dementia strategies between 2009 and 2015, including financial incentives to diagnose dementia.

“Of interest to me is that several important policies were implemented in 2012 to improve assessment and increase rates of diagnosis,” Tracey Gendron, MS, Ph.D., chair and associate professor at the Department of Gerontology at Virginia Commonwealth University, not involved in the study, told MNT.

“With an increased emphasis on increasing diagnosis, it is logical that increased reporting would follow in the decade since. A limitation is that it could be that doctors that receive more training are now better able to identify the signs and symptoms of cognitive decline and potentially miss reporting these cases prior to receiving the training,” she explained.

The researchers added that recordings of SMC are more in alignment with trends in dementia incidence, which have reportedly declined by 13% each decade over the last 25 years.

They nevertheless say that fewer cases of SMC were recorded in primary care than in the community at large, perhaps due to older people’s decision-making in seeking help for memory concerns and under-identification in primary care settings.

The researchers concluded that SMC and MCI predict a higher risk of developing dementia and that recording cases sooner increases the opportunity for early intervention.

Study limitations

“A key limitation is that as the authors only analyzed health records, they were unable to determine: (a) the nature of cognitive decline (e.g., memory, or other cognitive domains?), and (b) the magnitude of cognitive decline (i.e., how large that decline was over X years),” noted Dr. Lim.

“They also acknowledged that the classification of cognitive decline was based on a clinician’s ‘formal or informal cognitive assessment.’ This is very non-specific.”

“The authors have also referenced the observation from Wolters et al., 2020, that dementia incidence has declined by 13% per decade over the past 25 years, yet do not provide any discussion around how their findings on increases in cognitive decline run in contrast to this observation. While not all cognitive decline is related to dementia, all dementias are characterized by impairment in one or more domains of cognition,” she concluded.

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