Older adults who have a higher annual household income (HHI) were shown to be less likely than those with lower HHI to receive a dementia diagnosis after referral in Denmark, but more likely to receive that diagnosis earlier and at a less severe cognitive stage.
Dementia diagnosis and the stage in which it is detected may vary by socioeconomic status (SES), according to study findings published today in JAMA Network Open.
The impact of SES on health outcomes has been referenced across several prior studies, with factors such as access to care and affordability concerns associated with higher mortality risk in people overall and patients with conditions such as Parkinson disease (PD) and multiple myeloma.
Also increasing the risk of chronic disease development, the researchers of the present study note that dementia, a condition whose prevalence is expected to triple by 2050, has been associated in the past with SES.
“SES, commonly measured by educational level, income level, and occupation, has been recognized as a risk factor for dementia and dementia-related death given that low SES was found to be associated with an increased risk for both,” said the study authors.
They noted that although the prior studies showed an association between SES and dementia diagnosis and time of diagnosis, limitations existed in data collection, sample size, and access to care for participants.
Conducting the first register-based cross-sectional study to assess household income (HHI) and its association with diagnostic evaluation for dementia, they recruited 10,191 individuals from various Danish national registers who had received their first referral for diagnostic evaluation between January 1, 2017, and December 17, 2018 (mean [SD] age, 75  years; 53.7% women).
“Denmark offers universal, free health care services to all citizens regardless of their social or economic position,” explained the study authors. “Danish national registries record health, social, and economic data and can be linked at the individual level.”
Participants were evaluated for dementia diagnoses related to Alzheimer disease, PD, and other conditions, with stages at diagnosis characterized as cognitively intact, mild cognitive impairment but not dementia, or mild, moderate, or severe dementia. The annual HHI of participants was categorized as upper (n = 3394), middle (n = 3398), or lower tertiles (n = 3399) within 5-year interval age groups.
Participants of the lower-tertile HHI group were more likely than their upper-tertile counterparts to be women, have a lower educational level, live alone, and have multiple medical conditions. Of the study cohort, 8864 (86.8%) had a dementia diagnosis.
After conducting univariable and multivariable logistic and linear regressions adjusted for confounders such as age group, sex, and region of residence, findings indicated that participants within the upper-HHI tertile were less likely to receive a dementia diagnosis after referral compared with those in the lower tertile (odds ratio (OR), 0.65; 95% CI, 0.55-0.78).
There was no significant difference in dementia diagnosis between the middle-tertile and lower-tertile participants (OR, 0.92; 95% CI, 0.77-1.09).
Furthermore, fewer individuals with upper-tertile HHI presented with moderate (748 [22.0%]) or severe (147 [4.3%]) dementia at the time of diagnosis compared with individuals with middle-tertile HHI (moderate dementia: 882 [26.0%]; severe dementia: 185 [5.4%]) and lower-tertile HHI (moderate dementia: 902 [26.5%]; severe dementia: 193 [5.7%]).
Assessing this trend further, upper-tertile HHI was significantly inversely associated with cognitive severity stage at diagnosis compared with lower-tertile HHI (β, −0.16; 95% CI, −0.21 to −0.10). There was no significant difference in cognitive stage at diagnosis for lower- or middle-tertile HHI participants (β, 0.01; 95% CI, −0.04 to 0.06).
“The results of this study revealed a social inequality in dementia diagnostic evaluation: in Denmark, people with higher income seem to receive an earlier diagnosis,” concluded the study authors. “Public health strategies should target people with lower SES for earlier dementia detection and intervention.”
Petersen JD, Wehberg S, Packness A, et al. Association of socioeconomic status with dementia diagnosis among older adults in Denmark. JAMA Netw Open. Published online May 18, 2021. doi:10.1001/jamanetworkopen.2021.10432