Vascular risk factor associations with subjective cognitive decline and mild behavioural impairment

Subjective cognitive decline and mild behavioural impairment identify older persons more likely to have early Alzheimer's disease. Vascular co-pathologies may also contribute to new onset and persistent cognitive and behavioural symptoms later in life. We investigated vascular risk factor associations with subjective cognitive decline and mild behavioural impairment. Cross-sectional data for 1285 (81.0% female) participants without mild cognitive impairment or dementia enrolled in the Canadian Platform for Research Online to Investigate Health, Quality of Life, Cognition, Behaviour, Function, and Caregiving in Aging were analyzed. Vascular risk factors included body mass index class, self-reported clinician diagnoses of hypertension, high cholesterol, diabetes, self-reported smoking, and the cumulative number of vascular risk factors. Outcomes were the Everyday Cognition scale and Mild Behavioural Impairment Checklist. Logistic and negative binomial regressions were used to model odds and severity of subjective cognitive decline and mild behavioural impairment as a function of individual or cumulative vascular risk factors. Having three or more vascular risk factors (odds ratio = 1.23, 95% confidence interval [1.04-1.47]), actively smoking (odds ratio = 1.54, 95% confidence interval [1.29-1.82]), being overweight (odds ratio = 1.46, 95% confidence interval [1.22-1.74]), and having diabetes (odds ratio = 1.29, 95% confidence interval [1.09-1.53]) were associated with higher odds of subjective cognitive decline. Having any number of vascular risk factors was dose-dependently associated with higher odds of mild behavioural impairment, as were all five vascular risk factors individually; active smokers (odds ratio = 2.67, 95% confidence interval [2.25-3.18]) and obese persons (odds ratio = 2.29, 95% confidence interval [1.91-2.75]) had over twice the odds of mild behavioural impairment. Vascular risk factors associations with subjective cognitive decline were stronger in participants with mild behavioural impairment. All vascular risk factors were linked to higher Everyday Cognition and Mild Behavioural Impairment Checklist total scores, indicating greater subjective cognitive decline and mild behavioural impairment symptom severity. Overweight body mass index, hypertension, and high cholesterol associations with subjective cognitive decline and mild behavioural impairment were stronger in middle-aged adults than older adults, but diabetes and active smoking had greater effects in older adults. Vascular risk factors are strongly related to experiences of cognitive and behavioural changes in later life, even in the absence of objective cognitive impairment. Furthermore, vascular associations with subjective cognitive decline symptoms may be more pronounced in persons with concomitant behavioural decline. Vascular pathologies may contribute to both cognitive and behavioural markers traditionally linked to Alzheimer's disease in older persons, prior to mild cognitive impairment and dementia.