Background: Recent research has demonstrated that DBS sites in Alzheimer’s (AD) and Parkinson’s (PD) influencing cognition are functionally connected to the subiculum. However, the results are mixed, and it is unclear how or if DBS site-subiculum connectivity can be optimized to improve patient cognition. Methods: We studied how subiculum connectivity influenced cognitive outcomes in both PD (subthalamic nucleus) and AD (fornix) DBS patients (total n = 110). We first confirmed DBS site-subiculum connectivity had opposite cognitive effects in each disease. We next investigated patient factors underlying these opposing effects. Lastly, we related our findings back to clinical practice to guide DBS programming in PD and AD. Results: DBS site-subiculum connectivity correlated with cognitive improvement in AD but decline in PD. This was dependent upon hippocampal atrophy; such that higher subiculum connectivity was beneficial when the hippocampus was atrophic but deleterious when it was intact. Finally, we related our findings back to anatomy with cadaveric dissections and present how DBS stimulation can be optimized to improve patient cognition. Conclusions: DBS site-subiculum connectivity influences cognition but depends on patient factors. Thus, to optimize cognition based on patient factors, DBS electrodes can be programmed to stimulate subregions with higher or lower subiculum connectivity.

The decision of whether to grow old in one's home (also referred to as ageing in place (AIP)) or relocating to an institution is an ongoing negotiation process, which involves residential decisions and adaptation. This research aims to explore how childless older adults in rural China choose between AIP and institutionalisation. Through a qualitative study conducted in rural China among childless older adults, we explored the reasons why they make certain residential choices and how they adapted during the decision process. Twenty-five childless participants (aged 60–83) were interviewed. Findings suggested that they referred to the term ku (literally meaning ‘bitterness’; and a metaphor referring to ‘conducting farming and farm-related activities’) to explain their residential decisions. If a person could endure ku – sustain food and basic living through farming and farm-related activities, they tended to choose to age in place; otherwise, they chose to relocate to institutions. Ku represents a sense of mastery, encompassing the stressfulness and suffering aspect that requires adaptation. Three adaptive strategies were identified: (a) positive reappraising of the negative aspect of ku, (b) routinising ku, and (c) transcending the narrative of ku into a toughness identity. Our findings suggest that childless older adults struggled to achieve residential mastery while making residential decisions, even though a sense of mastery was shaped by the individual and structural constrictions.

Each species is subject to various biotic and abiotic factors during growth. This paper formulates a deterministic model with the consideration of various factors regulating population growth such as age-dependent birth and death rates, spatial movements, seasonal variations, intra-specific competition and time-varying maturation simultaneously. The model takes the form of two coupled reaction–diffusion equations with time-dependent delays, which bring novel challenges to the theoretical analysis. Then, the model is analysed when competition among immatures is neglected, in which situation one equation for the adult population density is decoupled. The basic reproduction number $\mathcal{R}_0$ is defined and shown to determine the global attractivity of either the zero equilibrium (when $\mathcal{R}_0\leq 1$) or a positive periodic solution ($\mathcal{R}_0\gt1$) by using the dynamical system approach on an appropriate phase space. When the immature intra-specific competition is included and the immature diffusion rate is neglected, the model is neither cooperative nor reducible to a single equation. In this case, the threshold dynamics about the population extinction and uniform persistence are established by using the newly defined basic reproduction number $\widetilde{\mathcal{R}}_0$ as a threshold index. Furthermore, numerical simulations are implemented on the population growth of two different species for two different cases to validate the analytic results.