Cognitive impairment has more than doubled since 2009, study suggests

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.