Survival and years of life lost in various aetiologies of dementia, mild cognitive impairment (MCI) and subjective cognitive decline (SCD) in Norway

Abstract

IntroductionAlzheimer’s disease patients are reported to have higher survival rate compared to patients with vascular dementia or dementia with Lewy bodies. There is a paucity of studies investigating survival including persons with cognitive decline and dementia of various aetiologies.ObjectivesWe aimed to compare survival for patients with subjective cognitive decline, mild cognitive impairment, Alzheimer’s disease, vascular dementia, mixed Alzheimer’s/vascular dementia, dementia with Lewy bodies/Parkinson’s disease, and other dementias compared to the general Norwegian population, taking into account the role of gender, cognitive function, function in everyday activities, comorbidity and education.MethodsPatients (N = 4682), ≥65 years, in the The Norwegian register of persons assessed for cognitive symptoms (NorCog) during 2009–2017 were followed for mortality in the National Registry until January 2018. Flexible parametric survival models were applied to estimate relative survival, life expectancy and years of life lost for diagnostic groups compared with the general population.ResultsPatients with vascular dementia or dementia with Lewy bodies/Parkinson’s had the shortest survival, followed by mixed dementia, Alzheimer’s disease, unspecified dementia, mild cognitive impairment and subjective cognitive decline. At age 70 years, men with vascular dementia or dementia with Lewy bodies/Parkinson’s had life expectancy of 4.7 years, which corresponded to 10.3 years of life lost compared to the general population. Years of life lost for other diagnoses were 10.0 years for mixed dementia, 9.2 years for Alzheimer’s disease, 9.3 years for other dementias, 5.2 years for mild cognitive impairment and 2.2 years for subjective cognitive decline. Corresponding years of life lost in women were: 12.7 years, 10.5 years, 9.8 years, 10.6 years, 7.8 years, and 2.6 years. Poor relative survival among dementia patients was associated with male gender, comorbidity, low cognitive function, and low function in activities of daily living.ConclusionsCompared with the general population, patients with subjective cognitive decline had no significant loss in life expectancy, while patients with mild cognitive impairment and all dementia subtypes had large losses, especially those with a diagnosis of vascular dementia or dementia with Lewy bodies/Parkinson’s.

Diagnostic diversity among patients with cognitive complaints: A 3‐year follow‐up study in a memory clinic

“…The mortality risks of our patients with dementia were comparable with the Swedish Dementia Registry (114 deaths/1000 person‐years), and our findings support the notion that old age and male gender are associated with poor survival among patients with cognitive complaints . Survival varied across dementia types and was found to be longer in AD than VaD, DLB, PDD, or mixed dementia (AD with VaD) . In our study, the survival difference among three diagnostic categories by the Kaplan‐Meier method disappeared after adjusting for age, gender, and baseline cognitive function in the Cox regression models.…”

“…8,11,24,25 Survival varied across dementia types and was found to be longer in AD than VaD, DLB, PDD, or mixed dementia (AD with VaD). 11,26 In our study, the survival difference among three diagnostic categories by the Kaplan-Meier method disappeared after adjusting for age, gender, and baseline cognitive function in the Cox regression models. Baseline MMSE scores, especially when lower than 17, were predictive of higher mortality risks.…”

Palliative Care in Advanced Dementia

“…Average post-diagnosis survival time for women (4.6–5.1 years) is longer than for men (4.1–4.3 years) ( 38 , 39 , 41 ), while life expectancy following diagnosis is determined individually by a number of predictors, e.g., age, sex, increased comorbidity, and type of dementia ( 42 – 44 ). People with vascular dementia or Lewy bodies have a shorter survival time than people with Alzheimer’s disease ( 45 , 46 ).…”

Cognitive Function and Mortality: Results from Kaunas HAPIEE Study 2006–2017

“…It is suggested that subjective cognitive impairment, which is recognised as a potential indicator for cognitive decline, is linked to all-cause mortality [8]. However, some studies argue that subjective cognitive decline does not predict mortality when objective cognitive deficits are controlled [9][10][11]. As scientists put it, complaints about cognitive abilities do not ultimately lead to cognitive impairment in all cases [10,11].…”

“…However, the link between cognitive function and mortality is not clear. Previous studies ascertained different links between cognitive decline and survival [9]. There also might be a difference in association according to the cause of death [19].…”