CHILDREN, DEPRESSION AND ESSENTIAL FATTY ACIDS

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INTRODUCTION

According to the World Health Organisation (WHO), major depression is likely the single greatest cause of years of life lost to disability worldwide (Global Health Forum for Research, 2008). In the United Kingdom, the cost of mental ill-health is currently estimated at £77 billion. This is greater than heart disease and cancer combined. By 2020, the WHO predicts a 50% rise in child mental health disorders (Global Health Forum for Research, 2008). The investigation of the relationship between diet and behaviour in children is of current scientific and government interest especially due to the rise in anti-social behaviour and reported increase in statements of special educational needs among UK school children and adolescents (Associate Parliamentary Food and Health Forum, 2008). Research efforts into nutrition and mental health are currently being undertaken with specific focus on the potential benefit of essential fatty acids (EFAs) to the mood, skills and cognitive development of young people (Sinn, Bryan & Wilson, 2008; Johnson, Östlund, Fransson, Kadesjo, & Gillberg, 2008; Gow, Matsudaira, Taylor, Crawford, Ghebremeskel, Ibrahimovic, ValléeTourangeau, Williams & Sumich., 2009). It is well established that polyunsaturated fatty acids are vital for the optimal development of both the brain and retina (Innis, 1991; 1997). They are abundant in the central nervous system and play a pivotal role in neurotransmission, serotonergic and dopaminergic function (Chalon, 2006). Several studies have reported
relationships between DHA intake in infants and increased visual acuteness, motor skills and IQ scores (Willats, Forsyth, DiModugno, Varma, & Colvin, 1998; Dunstan, Simmer, Dixon, & Prescott, 2008). In contrast, low maternal seafood consumption, that is less than 340 grams per week during pregnancy, is linked with higher scores of suboptimal outcome in children across a range of measures including fine motor skills, verbal IQ and social development (Hibbeln, Davis, Steer, Emmett, Rogers, Williams, & Golding, 2007). Furthermore, children
with lower levels of omega-3 fatty acids are reported to have more temper tantrums, sleep disorders and behavioural problems than controls (Burgess, Stevens, Zhang, & Peck, 2000). Following the publication of several randomised controlled trials which reported reductions in symptoms of depression following supplementation with fish oil (Peet & Horrobin, 2002; Jazayeri, Tehrani-Doost, Keshavarz, Hosseini, Djazayery, 2008), the American Psychiatric Association (2006) recommended that people with mood disorders such as depression should consume at least 1 gram of EPA and DHA daily (Freeman, Hibbeln, Wisner, Davis,
Mischoulon et al., 2006). However, the impact of nutrition in children in relation to depression is currently underfunded and under researched.

DEPRESSION IN CHILDREN AND ADOLESCENTS

Depression is a psychiatric disorder characterised by a shift in mood from pleasant to unpleasant, also known as dysphoria or a dysphoric mood (DSM-IV-TR, 2002). In teenagers it is linked to a range of negative outcomes and is often presented as irritability rather than displays of sadness or depression (DSM-IV-TR, 2002). A dysphoric mood is described as pervasive, persisting over time and sufficiently severe to disrupt ability and/or interest in
school work or spending time with friends. Physical characteristics and symptoms of depression can include a fluctuation in appetite, sleep disturbance, fatigue and loss of energy (DSM-IV-TR, 2002). It is also accompanied by other symptoms such as a diminished ability to think, concentrate or pay attention, indecisiveness, and feelings of worthlessness (DSM-IVTR, 2002). A negative or distorted self-image can often result in the loss or gain of weight in affected adolescents. It is important to note that for a diagnosis of depression, the presenting
symptoms should not be as a direct result of the misuse of substances and/or medication, nor be accounted for by a medical condition, or follow a bereavement/loss of a loved one (DSMIV-TR, 2002). An accurate assessment of depression can only really be obtained through direct questioning of the individual by significant others such as parents. For a clinical diagnosis at least 5 or more symptoms must be met according to the DSM-IV and be
persistent for a minimum duration of 2 weeks (DSM-IV-TR, 2002). Episodes of depression are changeable, ranging from mild, suggesting a slight deviation from normal functioning, to severe. In severe cases, the result is often an inability to look after one self which can result in psychiatric care (Harrington, 2003). Adolescents dealing with depressive symptoms might attempt to cope with affective problems by over-investing time and energy with certain types of peer groups, experimenting sexually, using illicit substances and self harm (Shaffer & Waslick, 2002; Harrington, 2001; Kovacs et al., 1993). Spitz (1946) was among the earliest researchers to examine depression in children. His work described the condition anaclitic depression which involved the separation of nursery infants from their mother. In addition, to withdrawal and weepiness, the children displayed
signs of loss of appetite, slow reactions and retardation of movement and development. Spitz and Wolf (1946) hypothesised that the most significant aetiological factor was the “loss of the love object”. Family dysfunction (along with emotional problems in parents) is also cited as a reliable predictor of continued depressive symptoms into early adulthood (Velez, Johnson, & Cohen, 1989). It is important to note, that no mention of nutrition is cited in the early literature concerning depression in children and adolescents. The knowledge and understanding that nutrition can mediate and influence brain function and neurotransmission has been largely overlooked from a psychiatric perspective until recently. The psychiatric approach in depression to date tends to focus on the association between genetic factors and low levels of the brain transmitters serotonin and norepinephrine (Davey, 2008). Stemming from this biological approach, various drugs have been developed with some success in an attempt to address these imbalances and alleviate symptoms of depression (Davey, 2008). However, there are adverse side effects to medication such as fluoxetine (Prozac) which include sexual dysfunction, headaches and gastric disorders (Rosen, Lane, & Menza, 1999). Moreover, fluoxetine use has recently been associated with an increased risk of suicide in teenagers and young adults (Gunnell, Saperia, & Ashby, 2005). Many patients
with depression are also treatment resistant and it has been noted, that complementary and alternative treatments, such as dietary supplements, are often sought as a replacement to conventional medication (NICE Guidelines, Appendix K, p. 199; Jorm, Korten, Rodgers, Pollitt, Jacomb, et al., 1997). Researchers working with paediatric populations have identified various risk factors for depression arising from a combination of biological, psychological, social/environmental and more recently genetic variables (Davey, 2008). However, little attention is paid to dietary influences, eating habits or nutrition and this is probably attributable to a lack of knowledge
on how these variables can mediate mood (Bamber, Stokes, & Stephen, 2007). Diet, along with other aspects of daily living such as exercise, has had a crucial role in the evolution of the brain and its cognitive capacities (Gomez-Pinilla, 2008; Crawford & Marsh, 1989). Recent advances in molecular biology have highlighted the ability that food has releasing signals which in turn can influence energy metabolism and synaptic plasticity. In other words, food has a mediating effect on cognitive function (Gomez-Pinilla, 2008). The action of specific dietary interventions, such as omega-3 fatty acids on the activation of molecular systems that are involved in synaptic plasticity has strong implications for public health and therapeutic interventions (Gomez-Pinilla, 2008). By understanding the molecular basis of the effects of food on cognition one can manipulate the diet in order to strengthen the resistance of neurons to damage while simultaneously promoting mental fitness (Gomez-Pinilla, 2008).
There is a pressing need for alternative support in the emotional and behavioural difficulties faced by some young people (Bamber, 2007).

It is estimated that 50% of referrals to child and adolescent mental health services in the UK alone could be markedly reduced if schools were equipped with evidence-based knowledge and the tools to carry out focused health programmes (Bamber, 2007) such as improvements in school meals. New research by Haskell, Scholey, Jackson, Elliot and Defeyter et al., (2008) has reported that providing
children with multi-vitamin and mineral supplementation improved performance in assessments of brain function; a proposition that warrants further investigation.

The manufacture of food has dramatically altered during the past century in favour of mass production; wheat and grains are now highly refined and stripped of much nutritional content; the addition of artificial additives and preservatives is in practically every supermarket foods; sugar and vegetable oils are refined and the result of the hydrogenation process is the novel trans fatty acid (Cordain, Boyd-Eaton, Sebastian, Mann, Lindeberg, et al., 2004). Arguably, these novel means of food production go against the evolution of the genome, have altered nutritional characteristics of ancestral hominid diets and contribute to the increase in diseases among so-called civilised populations (Cordain, 2004). The health
implications concerning the changes in agriculture and food production have not gone unnoticed. A letter to the Lancet by the scientist Hugh Sinclair (1956) argued that defects in intake or metabolism of EFAs may play a fundamental role in diseases common to Western society. However, his advice was deemed controversial as it contractided the current paradigm. He was not only ignored but subsequently ostracised by the medical society,
unable to obtain research grants to investigate this further. It is now established that an association exists between nutrition (and a lack of omega-3 fatty acids) and the rise in cardiovascular disease, obesity and mental illness (Horrobin, 1990; GISSI-HF, 2008; KleinPlatat, Drai, Oujaa, Schienger & Simon, 2005; Peet, 2002; Cordain ET AL., 2004).
In addition to EFAs, it is important to note that brain function requires an adequate amount of key vitamins and trace minerals such as zinc, magnesium, folate, iron, selenium, and the C and B family of vitamins (Watts, 2008). These are needed not only for the synthesis of DHA but for the production of serotonin, dopamine, noradrenaline and similar neurotransmitters (Watts, 2008). In spite of this knowledge, research by the U.S. Department
of Agriculture in the 1990’s suggested that children and adolescents are lacking in folate, magnesium, zinc, and vitamins A and E (The School Nutrition Dietary Assessment Study, 1993). In addition, research by Bruner, Joffe, Duggan, Casella, and Brandt, (1996) report that approximately 25% of adolescent girls in the United States are deficient in iron (Bruner, Joffe, Duggan, Casella, & Brandt, 1996). However, the affect of these deficiencies on brain function remain relatively unknown. A recent clinical trial which supplemented children and young people with zinc reported some promising results with significant improvements in hyperactive and restless behaviours (Bilici, Yildirim, Kandal, Bekaroglu, Yildirim, Deger et al., 2004).

In reference to food additives, a publication by McCann, Barrett, Cooper, Crumpler, Dalen et al., (2008) has confirmed that the preservative, sodium benzoate and artificial colouring can cause hyperactivity in children. High levels of hyperactive behaviours (inattention, over activity and impulsivity) in young children often result in a diagnosis of ADHD and are also associated with educational difficulties especially related to reading (McCann, Barrett, Cooper, Crumpler, Dalen et al., 2008; McGee, Prior, Williams, Smart, & Sanson, 2002). In light of the health importance of vitamins, minerals and essential fatty acids more research is required to address optimum intake and potential deficiencies in children, to further explore and understand the links between mental health and nutrition (Associate Parliamentary Food and Health Forum, 2008).

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