Cognitive decline in advanced age is closely related to dementia. The trajectory of cognitive function in older Chinese is yet to be fully investigated. We aimed to investigate the trajectories of cognitive function in a nationally representative sample of older people living in China and to explore the potential determinants of these trajectories.

This study included 2,038 cognitively healthy persons aged 65–104 years at their first observation in the Chinese Longitudinal Healthy Longevity Survey from 2002 to 2014. Cognitive function was measured using the Chinese version of the Mini-Mental State Examination (MMSE). Group-based trajectory modeling was used to identify potential heterogeneity of longitudinal changes over the 12 years and to investigate associations between baseline predictors of group membership and these trajectories.

Three trajectories were identified according to the following types of changes in MMSE scores: slow decline (14.0%), rapid decline (4.5%), and stable function (81.5%). Older age, female gender, having no schooling, a low frequency of leisure activity, and a low baseline MMSE score were associated with the slow decline trajectory. Older age, body mass index (BMI) less than 18.5 kg/m2, and having more than one cardiovascular disease (CVD) were associated with the rapid decline trajectory.

Three trajectories of cognitive function were identified in the older Chinese population. The identified determinants of these trajectories could be targeted for developing prevention and intervention strategies for dementia.

The prevalence and factors associated with delays in help seeking for people with dementia in China are unknown.

Within 1,010 consecutively registered participants in the Clinical Pathway for Alzheimer's Disease in China (CPAD) study (NCT01779310), 576 persons with dementia (PWDs) and their informants reported the estimated time from symptom onset to first medical visit seeking diagnosis. Univariate analysis of general linear model was used to examine the potential factors associated with the delayed diagnosis seeking.

The median duration from the first noticeable symptom to the first visit seeking diagnosis or treatment was 1.77 years. Individuals with a positive family history of dementia had longer duration (p = 0.05). Compared with other types of dementia, people with vascular dementia (VaD) were referred for diagnosis earliest, and the sequence for such delays was: VaD < Alzheimer's disease (AD) < frontotemporal dementia (FTD) (p < 0.001). Subtypes of dementia (p < 0.001), family history (p = 0.01), and education level (p = 0.03) were associated with the increased delay in help seeking.

In China, seeking diagnosis for PWDs is delayed for approximately 2 years, even in well-established memory clinics. Clinical features, family history, and less education may impede help seeking in dementia care.

Depression among older adults is under-recognized either in the community or in general hospitals in Chinese culture. This study aimed to develop a culturally appropriate screening instrument for late-life depression in the non-psychiatric settings and to test its reliability and validity for a diagnosis of depression.

Using a Delphi method, we developed a geriatric depression inventory (GDI), consisting of 12 core symptoms of depressive disorder in old age. We investigated its reliability and validity on 89 patients with late-life depression and 249 non-depression controls. Both self-report (GDI-SR) and physician-interview (GDI-RI) versions were assessed.

Cronbach's α coefficient was 0.843 for GDI-SR and 0.880 for GDI-RI. Both GDI-SR and GDI-RI showed good concurrent validity with the 15-item Geriatric Depression Scale (GDS-15) (GDI-SR: r = 0.750, p < 0.001; GDI-RI: r = 0.733, p < 0.001). The area under the curve of the receiver operating characteristic (ROC) was 0.938 for GDI-SR and 0.961 for GDI-RI, suggesting good to excellent discrimination of depression versus non-depression. Using a cut-off of three items endorsed, sensitivity and specificity were 92.1% and 81.9% for GDI-SR, and 93.3% and 87.1% for GDI-RI.

The GDI, either based on self-report or rater interview, is a reliable and valid instrument for the detection of depression among older adults in non-psychiatric medical settings in Chinese culture.