Table 4.

Studies on caffeine-related effects associated with SSB consumption

Author, Year	Setting	Sample Size	Sample Age	Method of Diet Assessment	SSB Unit of Analysis	Primary Outcome	Direction of Association	Findings
Cross-Sectional Studies
Azagba, 2014	Adolescents attending public schools in Atlantic Canada	8210	Grades 7, 9, 10 and 12	Self-reported survey with question asking about consumption of caffeinated energy drinks in past year	Energy drink more than once a month vs. one to two times	Odds of depression, sensation seeking, substance use	Positive	Sensation Seeking OR = 1.17 [95%CI: 1.11, 1.22]* Depressive symptoms, very elevated OR = 1.95 [95%CI: 1.36, 2.79]* Depressive symptoms, somewhat elevated OR = 1.08 [95%CI: 0.80, 1.47] Cigarette use OR = 2.58 [95%CI: 1.71, 3.89]* Marijuana use OR = 1.87 [95%CI: 1.37, 2.56]* Alcohol use OR = 2.48 [95%CI: 1.83, 3.36]* Other drug use OR = 1.80 [95%CI: 1.26, 2.57]*
Bashir, 2016	Convenience sample of patients in waiting areas of emergency department in U.S.	612	12-18 years	Questionnaire asking about frequency of energy drink consumption	Frequent (at least once a month) vs. Infrequent (less than once a month) consumers of energy drinks	Proportion of frequent vs. infrequent consumers experience of headache, anger and increased urination	Positive	Headache 76% [95%CI: 69-81] vs. 60% [95%CI: 55-64]* Anger 47% [95%CI: 40-54] vs. 32% [95%CI: 27-36]* Increased urination 24 [95%CI: 18-30] vs. 13 [95%CI: 10-16]* Study provides a number of outcomes. See paper for full results.
Koivusilta, 2016	Classroom survey of 7th grade students in Finland	9446	13 years	Self-reported online survey asking about frequency of energy drink consumption	Several times a day vs. not at all	Odds of headache, sleeping problems, irritation, tiredness/fatigue, late bedtime	Positive	Headache OR = 4.6 [95%CI: 2.8, 7.7] Sleeping problems OR = 3.6 [95%CI: 2.2, 5.8] Irritation OR= 4.1 [95%CI: 2.7, 6.1] Tiredness/ fatigue OR=3.7 [95%CI: 2.4, 5.7] Late bedtime OR = 7.9 [95%CI: 5.7, 10.9]
Kristjansson, 2013	School survey of children in Iceland	11,267	10-12 years	Questions on population-based survey asking about frequency of energy drink and cola consumption	≥1 cola/day vs. none ≥1 energy drink/ day vs. none	Odds of headaches, stomachaches, sleeping problems, low appetite	Positive	Colas Headaches Females: OR = 1.13 [95%CI: 0.87, 1.47] Males: OR = 1.29 [95%CI: 1.03, 1.62]* Stomachaches Females: OR = 1.40 [95%CI: 1.08, 1.80]* Males: OR = 1.31 [95%CI: 1.03, 1.67]* Sleeping problems Females: OR = 1.55 [95%CI: 1.21, 1.98]* Males: OR = 1.34 [95%CI: 1.09, 1.66]* Low appetite Females OR = 1.37 [95%CI: 1.03, 1.83]* Males OR = 1.44 [95%CI: 1.12, 1.86]* Energy Drinks Headaches Females: OR = 1.68 [95%CI: 1.17, 2.41]* Males: OR = 1.87 [95%CI: 1.43, 2.46]* Stomachaches Females: OR = 1.76 [95%CI: 1.21, 2.54]* Males: OR = 2.45 [95%CI: 1.86, 3.23]* Sleeping problems Females: OR = 1.56 [95%CI: 1.07, 2.25]* Males: OR = 1.63 [95%CI: 1.25, 2.12]* Low appetite Females OR = 2.31 [95%CI: 1.58, 3.39]* Males OR = 1.30 [95%CI: 0.95, 1.78]
Park, 2016	Nationally representative cohort of Korean adolescents	68,043	12-18 years	Web-based survey with questions on energy drink consumption	Highly frequent energy drink consumer (≥5 times/week) vs. infrequent energy drink consumer (<1 time/week) Moderate frequent energy drink consumer (1-4 times/week) vs. infrequent energy drink consumer	Odds of sleep dissatisfaction, perceived stress, persistent depressive mood, suicidal ideation, suicide plan, suicide attempt	Positive	Highly frequent energy drink consumer vs. infrequent energy drink consumer Sleep dissatisfaction OR = 1.64 [95%CI 1.61, 1.67]* Perceived stress OR = 2.23 [95%CI: 2.19, 2.27]* Depressive mood 2.59 [95%CI: 2.54, 2.65]* Suicidal ideation 3.14 [95%CI: 3.07, 3.21]* Suicidal plan 4.65 [95%CI: 4.53, 4.78]* Suicide attempt 6.79 [95%CI: 6.59, 7.00]* Moderate frequent energy drink consumer vs. infrequent energy drink consumer Sleep dissatisfaction OR = 1.25 [95%CI: 1.25, 1.26]* Perceived stress OR = 1.38 [95%CI: 1.37, 1.39]* Depressive mood OR=1.51 [95%CI: 1.49, 1.52]* Suicidal ideation OR=1.43 [95%CI: 1.42, 1.45]* Suicidal plan OR=1.78 [95%CI: 1.75, 1.81]* Suicide attempt OR=1.91 [95%CI: 1.87, 1.95]*
Richards, 2015	Adolescents from three secondary schools in the South West of England	2307	11-17 years	DABS survey (assesses intake of common dietary variables), including questions on energy drink and cola consumption	High consumption (≥1 can of energy drink or cola) vs. no consumption Low consumption (<1 can of energy drink or cola) vs. no consumption	Odds of stress, anxiety and depression	Mixed	High consumption vs. no consumption Energy Drinks Stress OR = 1.10 [95%CI: 0.80, 1.50] Anxiety OR = 1.05 [95%CI: 0.77, 1.43] Depression OR = 1.11 [95%CI: 0.81, 1.52] Cola Stress OR = 0.68 [95%CI: 0.52, 0.90]* Anxiety 0.83 [95%CI: 0.64, 1.09] Depression 1.23 [95%CI: 0.93, 1.62] Low consumption vs. no consumption Energy Drinks Stress 1.38 [95%CI: 1.05, 1.80]* Anxiety 1.26 [95%CI: 0.97, 1.64] Depression 0.99 [95%CI: 0.76, 1.31] Cola Stress 0.72 [95%CI: 0.56, 0.94]* Anxiety 0.86 [95%CI: 0.67, 1.10] Depression 1.18 [95%CI: 0.91, 1.54]
Longitudinal Studies
Marmorstein, 2016	Cohort of middle-school students in the U.S.	144	10-14 years, followed-up 16 months later	Self-reported questionnaire with questions on energy drink consumption	Energy drink consumption at baseline	Change in ADHD inattention, ADHD hyperactive, conduct disorder, depression, panic, anxiety at follow-up (controlling for coffee)	Mixed	ADHD inattention β = 0.20* ADHD hyperactive β = 0.20* Conduct disorder β = 0.18 Depression β = 0.08 Panic β = 0.17 Generalized anxiety β = 0.09 Social Anxiety β = -0.02

Note: * indicates statistical significance (p<0.05) as reported by each study