Introduction

There is a world-wide trend for an ageing of our populations. The proportion of Australians aged 65 years or over is predicted to increase from 13% (1.1 million) in 2010 to 23% (8.1 million) in 2050 [1]. Epidemiological surveys of the Australian population suggest that approximately 1 in 6 individuals over the age of 65 is diagnosed with a mental disorder in the 12 months prior to interview [2], with similar rates established internationally [3]. These statistics suggest that geriatric mental illness is common, and, in the future, the number of older adults living with mental illness will increase dramatically. One of the current challenges for global public health is the identification of mental health interventions that are effective and acceptable to older populations, and that have the potential for widespread dissemination.

Over recent years there has been a proliferation of internet delivered medical interventions across a wide range of clinical conditions. Randomised controlled trials have demonstrated the efficacy of internet delivered treatments, particularly those based on cognitive behavioural therapy (iCBT). Reviews of the literature indicate that iCBT is highly efficacious across a range of mental and physical disorders, with benefits in terms of patient accessibility and convenience [4]–[6]. Given the efficacy, cost effectiveness, scalability and adaptability of iCBT, the potential for widespread dissemination of these treatments is vast. Recent research has focused on the effectiveness of iCBT in practice [7]–[10]. These studies have shown that when iCBT is disseminated into practice, reductions in psychiatric symptoms and psychological distress are considerable, and commensurate with those achieved in randomised controlled trials. However, the acceptability, effectiveness and uptake of iCBT treatment for mental disorders has not been established in older populations [5], [6]. Given that rates of internet use vary considerably by age [11], age-based differences in the adoption of internet delivered treatments should be investigated.

In view of this, the current study aims to:

1. Investigate relative iCBT adherence rates amongst younger and older adults;
2. Establish whether younger and older adults gain similar treatment benefits from iCBT; and
3. Determine whether age-based patterns of enrolment for iCBT reflect the age distribution of mental illness in the general population.

The current study addresses these questions in data collected as part of routine quality assurance activities. The interventions to be assessed have been shown to be efficacious in several randomised controlled trials [12]–[17]. On the basis of these findings, these interventions were disseminated into general practice across Australia in 2010. This naturalistic study is based on the 2413 patients who were prescribed one of these interventions by their primary care physician since dissemination in October 2010.

Methods

Results

Table 1 lists the baseline characteristics of individuals prescribed the iCBT courses by age. When compared with those aged over 60 years, those in the 50–59 year age group were more likely to be based in a rural location, whilst those in the 30–39 year age group were more likely to live in an urban residence. Those aged over 60 years were more likely to complete all 6 lessons when compared with each of the younger age groups, except for those in the 50–59 year age group. Age groups were similar in terms of sex and prescribing clinician.

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Table 1. Baseline characteristics and adherence of individuals commencing iCBT courses for major depression, generalised anxiety disorder, panic disorder and social phobia by age.

https://doi.org/10.1371/journal.pone.0071825.t001

Table 2 displays the results from the marginal models with K10 and WHODAS-II scores as separate continuous outcome variables. In each model, the main effect of time was statistically significant (p<0.001 in both cases), indicating that psychological distress decreased and functioning increased significantly following iCBT. The interactions between time and age were not statistically significant, indicating that scores on both the K10 and WHODAS-II reduced at a similar rate for both age groups.

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Table 2. Estimated marginal K10 and WHODAS-II means and results from the marginal model with K10 and WHODAS-II scores as the outcome variables.

https://doi.org/10.1371/journal.pone.0071825.t002

Table 3 compares the age distribution of individuals initiating iCBT through This Way Up clinic with the age distribution of individuals meeting 12-month criteria for major depression, GAD, panic disorder and social phobia in the Australian population. When compared to those meeting criteria for social phobia in the Australian population, there were significantly more 18–29 year olds enrolling in the social phobia iCBT course. Otherwise, the age distribution of those enrolling in the iCBT courses matched the age distribution of those meeting criteria for each of the disorders in the Australian population.

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Table 3. Age distribution of individuals enrolling in the This Way Up Clinic iCBT courses and of those diagnosed with psychiatric disorders in the general population according to the 2007 Australian National Survey of Mental Health and Well-Being (NSMHWB).

https://doi.org/10.1371/journal.pone.0071825.t003

Discussion

These findings indicate that iCBT prescribed across a range of psychiatric disorders is effective and acceptable amongst older treatment-seeking populations. Reductions in psychological distress and improvements in functioning were significant and similar across age groups. Adherence, on the other hand, was more likely among older individuals when compared with their younger counterparts. The age distribution of those commencing iCBT treatment also matched the age distributions of those diagnosed with these disorders in the general population, indicating that iCBT successfully captures older individuals who need treatment.

This study was conducted within a naturalistic framework, which means that the external validity of these findings was maximised. However, these findings need to be interpreted within the context of some limitations. It was not possible to establish whether treatment effects were sustained over time due to the lack of follow up data. The lack of formal exclusion criteria also meant that patients may have been using adjunctive treatments which contributed to the magnitude of treatment effects.

When considering the older population, there are some barriers to the successful treatment of illness over the internet. For instance, older age groups report lower rates of internet use when compared with their younger counterparts [26]. Age-related issues, such as impairments in vision, manual dexterity and cognition have been identified as factors that may prevent the uptake of technology-based health interventions [27]. This has led to the popular belief that online treatments may not be suitable for older individuals, or that older individuals may be less willing to commence technology-based treatment. Reviews of iCBT for mental illness have indicated that older individuals are generally under-represented in the samples that provide efficacy data for these programs [5], [6]. This has precluded subgroup analyses based on age, however, positive and large effects for these interventions are often elicited after adjusting for age, providing preliminary evidence that these programs are effective across the age spectrum. Consistent with the current results, previous research has also indicated that older, compared with younger, individuals are more likely to adhere to these programs when completed under the care of their primary care physician [7], [10]. Taken together, these previous findings suggest that while iCBT interventions may be effective and acceptable regardless of age, the reach of these programs amongst older populations may be limited. The current study provides further evidence that online treatments for psychiatric illness are both effective and acceptable for older treatment-seeking patients. Importantly, the current findings also indicate that, when disseminated into general practice, the proportion of older adults commencing these programs is consistent with what would be expected.