the subject has received much media attention in recent years , partly in response to celebrity chef jamie oliver , who investigated the nutritional quality of school dinners in the uk ( bbc news 2004 ) . poor nutrition in childhood is associated with increased levels of childhood obesity and later morbidity ( ebbeling et al . in terms of behavioural problems , one randomised controlled trial found an association between the intake of artificial food colouring and preservatives , and parental ratings of hyperactivity in three year old children over the course of a week ( bateman et al . 2004 ) . however , studies have tended to focus on the addition or exclusion of specific chemicals or nutrients , and its effect on childhood behavioural problems ( hirayama et al . 2004 ) , rather than examining overall dietary patterns , which may provide greater potential for public health interventions . a narrative review has concluded that there is currently a lack of evidence from short - term experimental studies , for a causal relationship between sugar intake and behavioural problems ( bellisle et al . the review goes on to emphasise the importance of further understanding the contribution of diet to childhood hyperactivity . anecdotal news reports have suggested a reduction of short - term childhood behavioural problems with healthier diets ( bbc news 2005 ) . in response to some of this evidence , as well as concerns about increasing levels of childhood obesity , there have been tight restrictions placed on the advertising of  junk - food to children in the uk ( bbc news 2007 ) . additionally , campaigns such as encouraging the consumption of at least five portions of fruit and vegetables a day ( www.5aday.nhs.uk ) have been launched , and attempts made to improve the nutritional quality of food served in schools . in terms of the latter , the government guidelines stated that a balanced diet is important for child development and in improving short - term concentration among children and young people ( department for education and skills 2005 ) . a subsequent government regulatory impact assessment went further , and stated that  even moderate under - nutrition can have lasting effects and compromise cognitive development and school performance ( department for education and skills 2006 ) . however , there remains little evidence about the longer - term effects of poor nutrition on behavioural problems , over months or years , which are arguably of greater public health importance than shorter transient effects seen over hours or days . it has been shown that nutrition has the greatest effect on brain growth and development during the third trimester of pregnancy and in the first few months of life ( dobbing & sands 1973 ) . however , more recent research has suggested  growth spurts in brain development throughout the first decade of life , specifically between 2 - 4 years and between 6 - 8 years of age ( isaacs & oates 2008 ) . the avon longitudinal study of parents and children ( alspac ) allows the investigation of effects of childhood diet on behaviour months or years later . previous studies using alspac data have shown associations between childhood dietary patterns at ages three , four and seven , and school attainment at ages 10 - 11 ( feinstein et al . 2008 ) ; and between diet at age four and hyperactivity at age seven ( wiles et al . 2009 ) . however , evidence for the latter was weak , with the confidence interval only just excluding the null . further , dietary data was not collected at the same time point as baseline behavioural scores . given the evidence suggesting growth spurts in brain development at ages 2 - 4 and 6 - 8 it is possible that previous work it is important to understand the effects of diet during these key years on behaviour later in childhood . this study investigates the association between diet at 81 months ( 6 years 9 months ) , and the development of behavioural problems up to 97 months ( 8 years 1 month ) . 2001 ) . in short , all pregnant women in the former region of avon , uk , with an expected delivery date between april 1991 and december 1992 were invited to participate . ethical approval for the study was obtained from the alspac law and ethics committee and the local research ethics committees . childhood behavioural problems were measured using the strengths and difficulties questionnaire ( sdq , goodman 1997 ) , completed by mothers at 81 months and 97 months . the sdq comprises 25 questions , split into five sub - scales : hyperactivity , emotional symptoms , conduct problems , peer problems , and pro - social behaviour . scores for the sub - scales range from 0 to 10 , and the first four sub - scales are combined to calculate a total difficulties score , ranging from 0 to 40 . subscale scores were pro - rated if 1 or 2 items were missing ( www.sdqinfo.com/b4.html ) . a higher score indicates more problems , except for pro - social behaviour , where a lower score indicates more difficulties . the sdq has been shown to have good reliability , in terms of internal consistency and retest stability ( goodman 2001 ) . as the sdq scores were highly skewed , and even with the application of transformations did not fit a normal distribution , the scores were dichotomised . for the overall score and each of the five subscales , children were classified as having a particular behavioural problem if categorised as borderline , according to cut - offs suggested by goodman for each sdq subscale ( goodman 1997 ) . child - based dietary data were collected at 81 months by food frequency questionnaire ( ffq ) completed by the child 's main carer . the ffq enquired about the frequency of consumption  nowadays by the child of 90 different foods and drinks provided by the mother . principal components analysis ( pca ) with varimax rotation was performed on this dietary data , and is described in detail elsewhere ( northstone & emmett 2005 ) . junk , and was associated with high intake of processed and snack foods , high in fat and/or sugar . health - conscious , and was associated with vegetarian foods , rice , pasta , salad and fruit . traditional pattern was obtained which was associated with intake of meat , potatoes and vegetables . the  junk pattern was chosen as the main dietary exposure to investigate the effect of a poor diet on childhood behaviour . this dietary pattern encompassed foods more likely to contain additives and less likely to contain key vitamins . the ffq was used to estimate non - milk extrinsic sugar ( nmes ) intake for each child . the approximate weekly nmes intake was calculated by multiplying the weekly frequency of consumption of a food / food group ( assigned as follows :  never or rarely = 0 ,  once in 2 weeks = 0.5 ,  1 - 3 times per week = 2 ,  4 - 7 times per week = 5.5 , and  more than once a day = 10 ) by the nmes content ( obtained from the 5th edition of the mccance and widdowson 's composition of foods [ holland et al . 1991 ] and its supplements ) of a standard portion of that food , and summing this for all foods consumed . junk pattern score and mean weekly nmes intake at 81 months , and each sdq score at 97 months . children with scores above the cut - off ( or below for pro - social behaviour ) , or missing , for each sdq subscale at 81 months were excluded from that specific analysis in order to identify logistic regression was used with adjustment for confounding variables ( see below ) . adjustment for iq score data was available , primarily via self - completion questionnaires or hospital records , for a number of potential confounding factors . these included child factors ( gender , birth weight , gestational age , and iq score at eight years of age [ wechsler et al . 1992 ] ) ; maternal factors ( smoking during pregnancy , maternal age at delivery , maternal depression and anxiety scores when the child was 6 years of age [ cox et al . 2004 ; crown & crisp 1979 ] ) ; and markers of socioeconomic status ( weekly income , financial strain , maternal education , parental social class , housing tenure , household overcrowding , and car use ) . all analyses were conducted using spss version 12 ( spss inc 2003 ) and stata version 10 ( statacorp 2007 ) . for the purposes of the present analyses , multiple or premature births ( defined as less than 37 weeks gestation ) , and children born with major congenital diseases , were excluded , as were those missing data on birth weight or gestational age . this left a cohort of 12 942 singleton term infants , of whom 7727 children had full dietary data available at 81 months . almost all of these children had sdq data available ( n=7649 for total difficulties ; 7678 for hyperactivity ; 7685 for emotional ; 7691 for conduct ; 7684 for peer problems ; 7690 for pro - social ) . of these , between 10 and 24% of children were excluded for having sdq scores above the cut - off at baseline , as shown in table 1 ( n remaining = 6802 for total difficulties ; 6278 for hyperactivity ; 6697 for emotional ; 5846 for conduct ; 6596 for peer problems ; 6948 for pro - social ) . just over 60% of these had full covariate data excluding iq , and about 50% had full covariate data including iq ( see tables 3 and 4 for the numbers in each analysis ) . a small number of children had data on nmes intake but not full dietary data ; thus numbers were slightly higher for the sugar analyses . 2001 ) . in short , all pregnant women in the former region of avon , uk , with an expected delivery date between april 1991 and december 1992 were invited to participate . ethical approval for the study was obtained from the alspac law and ethics committee and the local research ethics committees . childhood behavioural problems were measured using the strengths and difficulties questionnaire ( sdq , goodman 1997 ) , completed by mothers at 81 months and 97 months . the sdq comprises 25 questions , split into five sub - scales : hyperactivity , emotional symptoms , conduct problems , peer problems , and pro - social behaviour . scores for the sub - scales range from 0 to 10 , and the first four sub - scales are combined to calculate a total difficulties score , ranging from 0 to 40 . subscale scores were pro - rated if 1 or 2 items were missing ( www.sdqinfo.com/b4.html ) . a higher score indicates more problems , except for pro - social behaviour , where a lower score indicates more difficulties . the sdq has been shown to have good reliability , in terms of internal consistency and retest stability ( goodman 2001 ) . as the sdq scores were highly skewed , and even with the application of transformations did not fit a normal distribution , the scores were dichotomised . for the overall score and each of the five subscales borderline , according to cut - offs suggested by goodman for each sdq subscale ( goodman 1997 ) . child - based dietary data were collected at 81 months by food frequency questionnaire ( ffq ) completed by the child 's main carer . the ffq enquired about the frequency of consumption  nowadays by the child of 90 different foods and drinks provided by the mother . principal components analysis ( pca ) with varimax rotation was performed on this dietary data , and is described in detail elsewhere ( northstone & emmett 2005 ) . junk , and was associated with high intake of processed and snack foods , high in fat and/or sugar . health - conscious , and was associated with vegetarian foods , rice , pasta , salad and fruit . traditional pattern was obtained which was associated with intake of meat , potatoes and vegetables . the  junk pattern was chosen as the main dietary exposure to investigate the effect of a poor diet on childhood behaviour . this dietary pattern encompassed foods more likely to contain additives and less likely to contain key vitamins . the ffq was used to estimate non - milk extrinsic sugar ( nmes ) intake for each child . the approximate weekly nmes intake was calculated by multiplying the weekly frequency of consumption of a food / food group ( assigned as follows :  never or rarely = 0 ,  once in 2 weeks = 0.5 ,  1 - 3 times per week = 2 ,  4 - 7 times per week = 5.5 , and  more than once a day = 10 ) by the nmes content ( obtained from the 5th edition of the mccance and widdowson 's composition of foods [ holland et al . 1991 ] and its supplements ) of a standard portion of that food , and summing this for all foods consumed . junk pattern score and mean weekly nmes intake at 81 months , and each sdq score at 97 months . children with scores above the cut - off ( or below for pro - social behaviour ) , or missing , for each sdq subscale at 81 months were excluded from that specific analysis in order to identify logistic regression was used with adjustment for confounding variables ( see below ) . adjustment for iq score data was available , primarily via self - completion questionnaires or hospital records , for a number of potential confounding factors . these included child factors ( gender , birth weight , gestational age , and iq score at eight years of age [ wechsler et al . 1992 ] ) ; maternal factors ( smoking during pregnancy , maternal age at delivery , maternal depression and anxiety scores when the child was 6 years of age [ cox et al . 2004 ; crown & crisp 1979 ] ) ; and markers of socioeconomic status ( weekly income , financial strain , maternal education , parental social class , housing tenure , household overcrowding , and car use ) . all analyses were conducted using spss version 12 ( spss inc 2003 ) and stata version 10 ( statacorp 2007 ) . the full alspac cohort comprises 14 541 pregnancies . for the purposes of the present analyses , multiple or premature births ( defined as less than 37 weeks gestation ) , and children born with major congenital diseases , were excluded , as were those missing data on birth weight or gestational age . this left a cohort of 12 942 singleton term infants , of whom 7727 children had full dietary data available at 81 months . almost all of these children had sdq data available ( n=7649 for total difficulties ; 7678 for hyperactivity ; 7685 for emotional ; 7691 for conduct ; 7684 for peer problems ; 7690 for pro - social ) . of these , between 10 and 24% of children were excluded for having sdq scores above the cut - off at baseline , as shown in table 1 ( n remaining = 6802 for total difficulties ; 6278 for hyperactivity ; 6697 for emotional ; 5846 for conduct ; 6596 for peer problems ; 6948 for pro - social ) . just over 60% of these had full covariate data excluding iq , and about 50% had full covariate data including iq ( see tables 3 and 4 for the numbers in each analysis ) . a small number of children had data on nmes intake but not full dietary data ; thus numbers were slightly higher for the sugar analyses . mean scores for each sdq sub - scale and for total difficulties at 81 months are shown in table 1 . these are presented alongside results from a large study conducted by the office for national statistics ( ons ) in 1999 investigating mental health of children and adolescents in great britain , to enable comparisons ( meltzer et al . alspac had lower total difficulties scores , and slightly lower hyperactivity , emotional and peer problems scores than the ons study , although in the main , scores were fairly similar . using the goodman cut - offs , the number of children classed as having behavioural problems ranged between 10% and 14% for total difficulties and each subscale except for conduct problems , which had a prevalence of 24% . junk pattern score in terms of how many were eating a variety of foods four or more times per week at 81 months . children in the highest quintile had higher consumption of crisps , chocolate coated biscuits and fizzy drinks . mean weekly nmes intake was normally distributed , with a mean of 494 g and a standard deviation of 185 g . mean nmes intake was consistent with that estimated in other uk studies ( rugg - gunn et al . 2007 ; mcneill et al . 2009 ) . junk pattern score at 81 months and both total difficulties and pro - social behaviour at 97 months ( table 3 ) . however , these associations attenuated substantially following adjustment for scores on these domains at 81 months , with the 95% confidence intervals including the null . adjustment for confounders similarly attenuated the modest associations observed between mean weekly nmes intake and behavioural problems ( in particular , total difficulties and conduct problems ) seen in unadjusted analyses ( table 4 ) . however , subjects with missing outcome data had similar baseline sdq scores to those with outcome data available . furthermore , there were few differences between those with or without outcome data in terms of other potential confounders such as socioeconomic status . mean scores for each sdq sub - scale and for total difficulties at 81 months are shown in table 1 . these are presented alongside results from a large study conducted by the office for national statistics ( ons ) in 1999 investigating mental health of children and adolescents in great britain , to enable comparisons ( meltzer et al . alspac had lower total difficulties scores , and slightly lower hyperactivity , emotional and peer problems scores than the ons study , although in the main , scores were fairly similar . using the goodman cut - offs , the number of children classed as having behavioural problems ranged between 10% and 14% for total difficulties and each subscale except for conduct problems , which had a prevalence of 24% . junk pattern score in terms of how many were eating a variety of foods four or more times per week at 81 months . children in the highest quintile had higher consumption of crisps , chocolate coated biscuits and fizzy drinks . mean weekly nmes intake was normally distributed , with a mean of 494 g and a standard deviation of 185 g . mean nmes intake was consistent with that estimated in other uk studies ( rugg - gunn et al . 2007 ; mcneill et al . 2009 ) . unadjusted analyses suggested associations between the  junk pattern score at 81 months and both total difficulties and pro - social behaviour at 97 months ( table 3 ) . however , these associations attenuated substantially following adjustment for scores on these domains at 81 months , with the 95% confidence intervals including the null . adjustment for other potential confounders further attenuated the effect ( table 3 ) . further adjustment for total iq score did not alter the findings . adjustment for confounders similarly attenuated the modest associations observed between mean weekly nmes intake and behavioural problems ( in particular , total difficulties and conduct problems ) seen in unadjusted analyses ( table 4 ) . just over half the cohort had complete data for the adjusted regression analyses . however , subjects with missing outcome data had similar baseline sdq scores to those with outcome data available . furthermore , there were few differences between those with or without outcome data in terms of other potential confounders such as socioeconomic status . junk food  diet at age 6  years and behavioural problems 16 months later . whilst , univariate analyses suggested an increase in behavioural problems at age 8 ( as measured by the total sdq score ) for those consuming greater quantities of  junk food  ( or sugar ) at age 6  years , after adjusting for confounding variables , the odds ratios were substantially attenuated , with the confidence intervals including one . similarly , there was no evidence to support an association between the individual subscale scores and diet after adjustment for potential confounders . these results show that although there is some evidence to suggest that poor diet is associated with greater levels of behavioural problems , it would appear that this association is due to confounding and there is little evidence supporting a causal link . the findings of this study appear to conflict with some previous research , and with anecdotal reports of dietary influences on childhood behaviour . however , this study set out to examine longer term effects of diet on childhood behaviour over several months , as opposed to shorter transient effects examined by others ( bateman et al . junk pattern at age 4 were more likely to have higher hyperactivity scores at age 7 ( wiles et al . however , the magnitude of this association was small with confidence intervals only just excluding the null value . furthermore , in addition to examining the association between dietary intake and total behavioural problems as measured by the sdq , this analysis also examined the association with the various subscales of the sdq and hence multiple analyses were carried out increasing the possibility of a type i error . importantly , the baseline diet and hyperactivity measures were not concurrent , and as such adjustments may not have been sufficient to eliminate all potential confounding . the findings of the current study would suggest that there is no association between a junk pattern score or sugar intake , and hyperactivity in children or other behavioural problems . a major strength of this study is the detailed data that has been collected over many years from a large prospective cohort . the collection of baseline sdq data at the same time as the dietary data allowed exclusion of those with behavioural difficulties at baseline . new cases of behavioural problems , removing the potential effect of reverse causality ; children with behavioural problems may well eat more junk food as parents find it harder to control their diet . additionally , the wealth of data collected throughout the cohort permitted adjustment for a number of potential confounding factors . it is possible that behavioural problems have been underestimated by some parents , which would have increased the likelihood of finding no association . however , previous studies have found parental ratings more sensitive for detecting hyperactivity in children than independent clinic ratings ( bateman et al . as the sdq scores were highly skewed , the outcomes were dichotomised , using cut - offs suggested by goodman ( 1997 ) . these cut - offs were originally designed so that approximately 10% of the general population would be classed as borderline. for the purposes of this study , children were categorised as having a behavioural problem if they were either abnormal or borderline according to the goodman scales . for all but conduct problems , the actual numbers with each behavioural problem this could suggest that there is some bias in which alspac participants returned the sdq questionnaires . this explanation is supported by the slightly lower mean sdq scores for all but conduct problems , when compared to a large ons study ( meltzer et al . , it may be that a higher cut - off would be more appropriate for children at this particular age ( about 7 years ) ; the original goodman scales were not age specific . this is difficult in practice , particularly with the subscales , due to having discrete data which can not be split into exact thirds . whilst just over half the cohort had complete data for the present analyses , those with missing outcome data were similar in terms of both baseline sdq scores and other potential confounders to those with outcome data . children categorised as having behavioural problems at baseline were excluded from the main analysis , in order to investigate thus this study only examined those classified as developing behavioural problems between the start and end of this study , that is between 81 and 97 months of age . it is possible that behavioural problems , if related to poor nutrition , generally develop earlier than 81 months , explaining the null finding of this study . however , this explanation is not supported by research on brain development , which has demonstrated a spurt in human brain growth between 6 and 8 years of age ( isaacs & oates 2008 ) . further , the proportion of children in this study developing behavioural problems between 81 and 97 months was as high as 12% for peer problems . it is possible that using pca to determine underlying patterns in the diet may not be the optimum method for the study of this particular outcome . it is possible that using other dietary pattern methods such as cluster analysis or a priori scores such as the health eating index ( kennedy et al . 1995 ) may have provided more positive associations . however , pca has the advantage of identifying underlying dietary patterns within the data rather than creating pre - defined dietary scores based on pre - conceptions of which food items constitute a healthy diet . in addition , dietary intake was assessed using ffqs , rather than the gold standard of weighed dietary records . however , studies comparing the results of pca using ffqs and weighed dietary records ( hu et al . ; togo et al . 2003 ) have found the resulting patterns to be comparable . junk food  diet at age 6  years and behavioural problems 16 months later . whilst , univariate analyses suggested an increase in behavioural problems at age 8 ( as measured by the total sdq score ) for those consuming greater quantities of  junk food  ( or sugar ) at age 6  years , after adjusting for confounding variables , the odds ratios were substantially attenuated , with the confidence intervals including one . similarly , there was no evidence to support an association between the individual subscale scores and diet after adjustment for potential confounders . these results show that although there is some evidence to suggest that poor diet is associated with greater levels of behavioural problems , it would appear that this association is due to confounding and there is little evidence supporting a causal link . the findings of this study appear to conflict with some previous research , and with anecdotal reports of dietary influences on childhood behaviour . however , this study set out to examine longer term effects of diet on childhood behaviour over several months , as opposed to shorter transient effects examined by others ( bateman et al . junk pattern at age 4 were more likely to have higher hyperactivity scores at age 7 ( wiles et al . 2009 ) . however , the magnitude of this association was small with confidence intervals only just excluding the null value . furthermore , in addition to examining the association between dietary intake and total behavioural problems as measured by the sdq , this analysis also examined the association with the various subscales of the sdq and hence multiple analyses were carried out increasing the possibility of a type i error . importantly , the baseline diet and hyperactivity measures were not concurrent , and as such adjustments may not have been sufficient to eliminate all potential confounding . the findings of the current study would suggest that there is no association between a junk pattern score or sugar intake , and hyperactivity in children or other behavioural problems . a major strength of this study is the detailed data that has been collected over many years from a large prospective cohort . the collection of baseline sdq data at the same time as the dietary data allowed exclusion of those with behavioural difficulties at baseline . new cases of behavioural problems , removing the potential effect of reverse causality ; children with behavioural problems may well eat more junk food as parents find it harder to control their diet . additionally , the wealth of data collected throughout the cohort permitted adjustment for a number of potential confounding factors . a potential limitation of the study is the use of parentally completed sdq scores . it is possible that behavioural problems have been underestimated by some parents , which would have increased the likelihood of finding no association . however , previous studies have found parental ratings more sensitive for detecting hyperactivity in children than independent clinic ratings ( bateman et al . 2004 ) . as the sdq scores were highly skewed , the outcomes were dichotomised , using cut - offs suggested by goodman ( 1997 ) . these cut - offs were originally designed so that approximately 10% of the general population would be classed as borderline. for the purposes of this study , children were categorised as having a behavioural problem if they were either abnormal or borderline according to the goodman scales . for all but conduct problems , the actual numbers with each behavioural problem this could suggest that there is some bias in which alspac participants returned the sdq questionnaires . this explanation is supported by the slightly lower mean sdq scores for all but conduct problems , when compared to a large ons study ( meltzer et al . , it may be that a higher cut - off would be more appropriate for children at this particular age ( about 7 years ) ; the original goodman scales were not age specific . this is difficult in practice , particularly with the subscales , due to having discrete data which can not be split into exact thirds . whilst just over half the cohort had complete data for the present analyses , those with missing outcome data were similar in terms of both baseline sdq scores and other potential confounders to those with outcome data . children categorised as having behavioural problems at baseline were excluded from the main analysis , in order to investigate thus this study only examined those classified as developing behavioural problems between the start and end of this study , that is between 81 and 97 months of age . it is possible that behavioural problems , if related to poor nutrition , generally develop earlier than 81 months , explaining the null finding of this study . however , this explanation is not supported by research on brain development , which has demonstrated a spurt in human brain growth between 6 and 8 years of age ( isaacs & oates 2008 ) . further , the proportion of children in this study developing behavioural problems between 81 and 97 months was as high as 12% for peer problems . it is possible that using pca to determine underlying patterns in the diet may not be the optimum method for the study of this particular outcome . it is possible that using other dietary pattern methods such as cluster analysis or a priori scores such as the health eating index ( kennedy et al . 1995 ) may have provided more positive associations . however , pca has the advantage of identifying underlying dietary patterns within the data rather than creating pre - defined dietary scores based on pre - conceptions of which food items constitute a healthy diet . in addition , dietary intake was assessed using ffqs , rather than the gold standard of weighed dietary records . however , studies comparing the results of pca using ffqs and weighed dietary records ( hu et al . ; togo et al . 2003 ) have found the resulting patterns to be comparable . this study has shown that neither junk food diet nor nmes intake at 81 months increase the risk of development of behavioural problems over the next 16 months . in response to public concern over the nutritional quality of children 's diets , the uk government increased funding for meals provided in schools ( bbc news 2005b ) and there have been general health campaigns to encourage healthier eating habits at home , such as promoting eating at least five portions of fruit and vegetables a day ( www.5aday.nhs.uk ) . increased behavioural problems these interventions are likely to be justified in terms of reducing obesity and improving general physical health ( ebbeling et al . 2002 ; must & strauss 1999 ) , but an effect on long - term childhood behaviour is not supported by this study .
objectiveto investigate whether a  junk food diet at 81 months of age is associated with the development of behavioural problems over the following 16 months.subjects/methodsthe study used data from the avon longitudinal study of parents and children ( alspac ) and 12,942 children were included . 
 the main outcome measure was behavioural problems , measured using the strengths and difficulties questionnaire ( sdq ) . 
 sdq scores were available at 81 and 97 months of age . 
 child - based dietary data were collected at 81 months by food frequency questionnaire ; from this a  junk food score was derived , and mean weekly non - milk extrinsic sugar ( nmes ) intake estimated . 
 statistical analyses examined the associations between dietary exposures at 81 months and sdq outcomes at 97 months . 
 children with sdq scores suggesting behavioural problems at baseline were excluded in order to identify new cases . 
 adjustments were made for potential confounders such as socioeconomic status.resultsunadjusted analyses suggested associations between the  junk food score at 81 months and both total difficulties and pro - social behaviour at 97 months . 
 however , adjustment for baseline sdq scores attenuated these associations , with confidence intervals including the null for both total difficulties [ or(95% ci):1.05(0.92,1.21);p=0.45 ] and pro - social behaviour [ 1.13(1.00,1.26);p=0.04 ] . 
 adjustment for other potential confounders further attenuated the effects . 
 adjustment for confounders similarly attenuated modest associations between nmes intake and behavioural problems.conclusionsthere was no evidence to support an association between a 
 junk food diet at 81 months of age and behavioural problems 16 months later .