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Rebecca Crabb

Publications and source records attributed to Rebecca Crabb.

2 recordsLinked to original sources

Utilization of mental health care services among older adults with depression.

Despite the availability of effective treatments for late life depression, data indicate that only a small minority of adults over the age of 65 years with depression access any kind of care for emotional or mental health problems. Using data from the Canadian Community Health Survey (Cycle 1.1), we compared patterns of mental health service utilization among middle-aged (45-64 years), younger old (65-74 years), and older old (75 years and older) adults with and without depression and identified predictors associated with accessing different services (n=59,302). Compared to middle-aged adults with depression, individuals aged 65 and older with depression were less likely to report any mental health consultation in the past year and especially unlikely to report consulting with professionals other than a family physician. Age remained a significant predictor of mental health service utilization even after accounting for other relevant variables such as gender, marital status, years of education, depression caseness, and number of chronic medical conditions. Although the prevalence of depression is lower in older age groups, the present study provides compelling evidence that mental health services are particularly underutilized by depressed older adults.

Age Factors↗

Propagating fronts, chaos and multistability in a cell replication model.

Numerical solutions to a model equation that describes cell population dynamics are presented and analyzed. A distinctive feature of the model equation (a hyperbolic partial differential equation) is the presence of delayed arguments in the time (t) and maturation (x) variables due to the nonzero length of the cell cycle. This transport like equation balances a linear convection with a nonlinear, nonlocal, and delayed reaction term. The linear convection term acts to impress the value of u(t,x=0) on the entire population while the death term acts to drive the population to extinction. The rich phenomenology of solution behaviour presented here arises from the nonlinear, nonlocal birth term. The existence of this kinetic nonlinearity accounts for the existence and propagation of soliton-like or front solutions, while the increasing effect of nonlocality and temporal delays acts to produce a fine periodic structure on the trailing part of the front. This nonlinear, nonlocal, and delayed kinetic term is also shown to be responsible for the existence of a Hopf bifurcation and subsequent period doublings to apparent "chaos" along the characteristics of this hyperbolic partial differential equation. In the time maturation plane, the combined effects of nonlinearity, nonlocality, and delays leads to solution behaviour exhibiting spatial chaos for certain parameter values. Although analytic results are not available for the system we have studied, consistency and validation of the numerical results was achieved by using different numerical methods. A general conclusion of this work, of interest for the understanding of any biological system modeled by a hyperbolic delayed partial differential equation, is that increasing the spatio-temporal delays will often lead to spatial complexity and irregular wave propagation. (c) 1996 American Institute of Physics.

Journal Article↗