Clinical considerations
The application of Lifestyle Medicine should be considered in the context of long-term sustainability. Motivational issues, time restrictions, financial limitations, the perspective about the source of their difficulties and treatment priorities, may influence a patient’s ability to implement lifestyle changes. Adherence and engagement are increased by having ownership of a treatment plan and a sense of shared partnership in its development and planning. Treatment strategies should therefore be developed taking cognisance of the above factors, and the treatment package should be individually tailored and offered in a step-wise manner. It is also necessary to consider readiness to change when engaging in discussion regarding lifestyle modification, and concordant with the transtheoretical model, to only embark on this when the person has moved beyond precontemplation to the contemplation or preparation stages [
140]. Some lifestyle choices and “vices” may provide the person self-perceived support and comfort, and in such cases change needs to be handled delicately. Often, strict advice promoting abstinence, or a demanding diet or exercise regime, may cause added suffering, and may also provoke guilt if the person cannot meet these expectations, or lead to paradoxical behaviour if oppositional cognitive schema are activated.
With respect to specific dietary advice, it is important to recognise that the nutrients critical for neurological function (magnesium, folate, zinc and essential fatty acids), and are all components of a healthy diet, found primarily in foods such as leafy green vegetables, legumes, wholegrains, lean red meat and fish. Foods rich in polyphenols (e. g. berries, tea, dark chocolate, wine and certain herbs), are also valuable for cognitive and cardiovascular function [
141,
142]. Aside from having adequate wholefoods, people are also advised to reduce processed foods, refined carbohydrates and sugars, and transaturated fats. Adherence to the Mediterranean diet has also been shown to be associated with a range of mental health benefits.
Regarding the dosage and type of exercise to recommend, research indicates that a dose-dependent effect occurs, with regular moderate to strong intensity exercise eliciting more positive results [
143,
144]. Clinical guidelines for exercise recommend physician assessment (or referral to an exercise physiologist) before commencing a new regime, which should consist of moderate to vigorous aerobic exercise (30–60 minutes) in addition to anaerobic weight-bearing exercises approximately four to six days per week [
145,
146]. Exposure to social interaction and nature when exercising may be useful on theoretical grounds.
The integration of meditative practices can be readily incorporated into most people’s lifestyle. While regular formal practice of meditation or yoga can be recommended, it can be applied in simple forms, such as mindful walking or eating, or yoga breathing exercises. With respect to yoga, it is advised that people pursue instruction under a qualified instructor, and proceed in a graded manner; as is the case for all forms of exercise. Patients with glaucoma (with any inverted poses), osteoporosis (with any heavy weight-bearing pose), should proceed with caution.
Due to the potential impact of heavy alcohol use on the risk and treatment for depression [
147,
148], routine clinical questioning about alcohol consumption is appropriate. In a clinical setting, the focus should be on differentiating and managing problem drinking (where it is identified), and on psycho-education of patients regarding modest alcohol consumption and avoiding heavy episodic drinking. Further education may be required regarding potential interactions between alcohol use and medications. Techniques combining motivational interviewing and cognitive behavioural therapy may be of benefit in treating the dual components of depression and problem drinking [
149,
150].
Smoking cessation should also form a routine component of clinical care, with individuals being offered evidence-based smoking cessation interventions when appropriate [
151]. Interestingly, PA used concurrently with smoking cessation seems to be protective against relapse in quitters, further reinforcing recommendations regarding exercise [
152]. One caveat is required: the act of cessation is associated with withdrawal symptoms including transient dysphoria, irritability and a risk of aggravation of depression [
153]. However, once the neurochemical set-point has re-adapted to the absence of nicotine, this should normalize. While trials of smoking cessation that examine long term change in depression risk have not been conducted, recent data suggests that quitting smoking is associated with better social functioning and self-perceived health status [
154].
Sleep hygiene techniques that can be offered in the case of poor sleep or insomnia, includes focusing on adjusting caffeine use, limiting exposure to the bed (sleep restriction) with the patient having only a limited time to sleep, and getting up at a set time in the morning [
155]. This should regulate the circadian rhythm, which is of particular significance in people with affective disorders [
115]. Reducing exposure to light prior to sleep to increase melatonin secretion is of theoretical value [
156], as is increased exposure to morning sunlight upon waking. Further sleep hygiene advice includes stimulus control: avoidance of stimulating activity and stimulants close to sleep (for example, smoking, caffeine and stimulating TV or books), and quiescent sleep preparation. Although evening meal portions should not be excessive (this may cause rebound hypoglycaemia), sufficient calorific intake is required to avoid waking up due to hunger.
Other lifestyle targets can consist of emphasising the importance of social contact, and the theoretically positive benefits of animals/pets [
122,
139]. The therapeutic benefits of spending time in nature is supported by a limited dataset [
129]. Adequate exposure to sunlight should enhance vitamin D levels and serotonin turnover [
157], however this needs to be balanced with concerns over skin cancer, thus time of day/year and skin colour are factors in consideration about the amount of sun exposure recommended. While current data are weak with respect to an association with depression, limited exposure to environmental toxins, chemicals pollutants [
136] and noise pollution [
158], is also a valid general health consideration. While limited study in this area has been pursued and there is no direct link to depression, moderation of excessive technological interface (e.g. mobile phones, computers, television) is also a potential consideration in Lifestyle Medicine [
2].
Summary
While many factors, including genetics, personality and cognition, and environmental stressors contribute to the aetiology of depression, lifestyle components may have an important role in the disorder’s pathogenesis. Currently, the contemporary clinical management of depression has had more of a focus on medication and psychotherapy, and to date, has not widely incorporated the evidence regarding many lifestyle factors into guidelines. As outlined above, there is evolving evidence to support the modification of selected lifestyle elements. Further research is now needed to study “integrative models” assessing the application of prescriptive Lifestyle Medicine, similar to those used in other medical populations [
159]. Trial designs could explore individualized tailored programs, or the step-wise application of individual components according to patient interest or need. While the study would not be double-blinded, it is possible to randomize participants into the active lifestyle modification group versus a placebo or inactive group, with the outcomes being assessed by an independent blinded researcher (using validated psychiatric scales). Further work exploring the mechanistic underpinnings of lifestyle modification is also of benefit.
In future respect to the research underpinning lifestyle modification for depression, aside from prospective RCTs needing to assess some lesser studied lifestyle elements such as dietary modification, one critical area of study is to explore the effects of an integrated multi-faceted application of lifestyle medicine. To date, to our knowledge only one RCT has examined the effects of combining multiple lifestyle adjustments for the treatment of depression. Garcia-Toro and colleagues [
160] conducted an RCT of 80 outpatients with diagnosed major depressive disorder (non-SAD) who were taking antidepressant treatment. Four specific lifestyle recommendations consisting of dietary modification, exercise, sunlight exposure and sleep patterns were prescribed in the active group, while the control group was given instruction to perform a pattern of eating, sleeping, exercise and exposure to light which they considered might make them feel better. Blinded assessment was conducted before and after the six month intervention period. The active group had a significantly greater reduction of depression than the control group, with 11 out of 40 people (28%) in the active group achieving remission (HAM-D < 7), compared to only one person in the control group. These encouraging results are in line with remission rates of standard antidepressants, and support the conduct of similar more definitive studies.