Hygienic-dietary recommendations for major depression treatment: Study protocol of a randomized controlled trial

Depression is a highly prevalent mental disorder in our society, with 10 to 20% of the population experiencing a major depressive disorder/depressive episode during their lives [1‐4]. From the health care system perspective, some studies confirm that 25-35% of patients consuming Primary Care services have a psychiatric condition, with over 80% of these patients presenting depression or anxiety disorders [5]. It is well known that General Practitioners (GPs) only refer approximately 5-10% of the psychiatric patients detected in Primary Care to Mental Health Services [6]. Despite this low referral rate, Mental Health Services in occidental countries are currently congested due to the high prevalence of minor psychiatric problems and this situation is very likely to worsen in the future [7]. Thus, it is of great interest to propose cost-effective alternatives for depression treatment in Primary Care settings which could improve efficacy to standard treatment while tolerability and security levels are sustained.

An essential issue regarding this alarming increment of the incidence and prevalence rates of depression is the fact that it seems to be occurring mainly in occidental countries [8, 9]. Hence, it is necessary to rapidly clarify which variables could explain this trend in order to modify them [9, 10]. It is presumed that lifestyle in occidental countries contribute to this increase in depression rates although specific factors involved have not been yet identified [8‐10]. No important findings from the point of view of genetics or neurobiological factors have been published within the last decades, with the exception of a probable increase in alcohol and other drugs consumption which in any case is not sufficient to fully explain this trend [11]. Consequently, it has been more frequently attributed to environmental changes in our lifestyle especially those related to stress, nonconformity, competitiveness and loss of social relationships [12]. Besides the great importance of these described factors, in recent times other variables have been submitted which might possibly influence this increase [13]. In this sense, it has been suggested that occidental lifestyle implies changes in diet, hours of sleep, sun exposure and physical activity, all of which could play a role as a mediator variable for depression onset [8, 9, 12, 13]. More and more people are decreasing their physical activity level and following a less healthy diet [14, 15]. Moreover, there is a tendency towards a reduction of sleep hours and time of sunlight exposure [16, 17]. It is well known that these changes impact the physiology of the brain which can lead to an increment in the vulnerability to depression [8]. Accordingly, it is not surprising that adjusting sleep hours, physical exercise, diet and sunlight exposure have been recommended separately by different research groups as a complementary or adjuvant treatment to pharmacotherapy and psychotherapy [18‐20]. However, there is little investigation about the usefulness of GPs giving these simple hygienic-dietary measures as a recommendation jointly to antidepressant treatment in usual clinical practice conditions [9, 12].

We conducted a preliminary study [9, 13] where 80 patients undertaking standard treatment with antidepressants were randomly assigned to two groups. Patients in the intervention group received written recommendations about physical exercise, Mediterranean diet, sunlight exposure and sleep control. Obtained results were encouraging [9].

This study represents a great opportunity for the improvement with minimal costs of the effectiveness of depression treatment. Results of a preliminary study [9, 13] pointed out that significant improvement of depressive symptoms can be achieved with this simple intervention. Its feasibility for the sanitary system derives from its low time consumption for health providers and the low cost of its implementation. Moreover, no significant adverse events or security problems derived from this intervention are expected.

Considering the low-restrictive nature of inclusion and exclusion criteria of the present study, problems for the recruitment of patients are not expected. The sample size will enable the determination of the profile of patients that could benefit from this simple intervention. It will also provide a better understanding of the reasons why some patients do not adhere to these recommendations, with the objective of eliminating this trend. The development of this research line in Primary Health Care settings is of great interest as well.

However, this study also has some limitations that will be taken into account. The main limitation derives from the fact that although GPs will be blinded to patient allocation, it is presumed that they will easily be able to identify which group the patient has been assigned to in the follow-up assessments. This is a potential bias as GPs could be induced to change pharmacological treatments based on this knowledge. In order to minimize this effect, we will ask participant GPs to stay as oblivious to patient allocation as possible. In case patient allocation is suspected, they will be asked to maintain a neutral attitude to patient comments regarding the recommendations they have received. Raters will also be blinded to treatment condition but, again, it will be easy for them to suspect patient allocation from the information provided by patients during the assessments. This could obviously introduce involuntary bias. To correct this possible bias, self-applied instruments will be preferred as main outcome variables.

MG is the principal researcher of this project and drafted the manuscript with the assistance of BO and SM. MG, MR, MG, MV, SM, BO, EV and JS were substantially involved in the conception of the study and participated in its design. EV and BO contributed to the development and implementation of the intervention. All authors contributed to the editing of the manuscript and have read and approved the final manuscript.