Gemma Lewis

Dr. Gemma Lewis

Epidemiology and Applied Clinical Research Department, Division of Psychiatry, University College London, London W1T 7NF, UK

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2021 in The Lancet Psychiatry
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Journal Article
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SLSiu Long Lee
Siu Long Lee
EPEiluned Pearce
Eiluned Pearce
OAOlesya Ajnakina
Olesya Ajnakina
SJSonia Johnson
Sonia Johnson
GLGlyn Lewis
Glyn Lewis
GLGemma Lewis
Gemma Lewis

4 May 2016 in PLOS ONE
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AHAnne-Laura Van Harmelen
Anne-Laura Van Harmelen
JGJenny Gibson
Jenny Gibson
MCMichelle St Clair
Michelle St Clair
MOMatt Owens
Matt Owens
JBJeannette Brodbeck
Jeannette Brodbeck
IGIan M Goodyer
Ian M Goodyer
Early life stress (ELS) consists of child family adversities (CFA: negative experiences that happened within the family environment) and/or peer bullying. ELS plays an important role in the development of adolescent depressive symptoms and clinical disorders. Identifying factors that may reduce depressive symptoms in adolescents with ELS may have important public mental health implications. We used structural equation modelling and examined the impact of adolescent friendships and/or family support at age 14 on depressive symptoms at age 17 in adolescents exposed to ELS before age 11. To this end, we used structural equation modelling in a community sample of 771 adolescents (322 boys and 477 girls) from a 3 year longitudinal study. Significant paths in the model were followed-up to test whether social support mediated or moderated the association between ELS and depressive symptoms at age 17. We found that adolescent social support in adolescence is negatively associated with subsequent depressive symptoms in boys and girls exposed to ELS. Specifically, we found evidence for two mediational pathways: In the first pathway family support mediated the link between CFA and depressive symptoms at age 17. Specifically, CFA was negatively associated with adolescent family support at age 14, which in turn was negatively associated with depressive symptoms at age 17. In the second pathway we found that adolescent friendships mediated the path between peer bullying and depressive symptoms. Specifically, relational bullying was negatively associated with adolescent friendships at age 14, which in turn were negatively associated with depressive symptoms at age 17. In contrast, we did not find a moderating effect of friendships and family support on the association between CFA and depressive symptoms. Friendships and/or family support in adolescence mediate the relationship between ELS and late adolescent depressive symptoms in boys and girls. Therefore, enhancing affiliate relationships and positive family environments may benefit the mental health of vulnerable youth that have experienced CFA and/or primary school bullying.

31 July 2020 in JMIR mHealth and uHealth
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TMTayla McCloud
Tayla McCloud
RJRebecca Jones
Rebecca Jones
GLGemma Lewis
Gemma Lewis
VBVaughan Bell
Vaughan Bell
ETElias Tsakanikos
Elias Tsakanikos
Background: Depression and anxiety symptoms are common among university students, but many do not receive treatment. This is often because of lack of availability, reluctance to seek help, and not meeting the diagnostic criteria required to access services. Internet-based interventions, including smartphone apps, can overcome these issues. However, a large number of apps are available, each with little evidence of their effectiveness. Objective: This study aims to evaluate for the first time the effectiveness of a self-guided mobile app, Feel Stress Free, for the treatment of depression and anxiety symptoms in students. Methods: A web-based randomized controlled trial compared a cognitive behavioral therapy (CBT)–based mobile app Feel Stress Free with a wait-list control. University students self-identified as experiencing symptoms of anxiety or depression and were randomized to 6 weeks of intervention (n=84) or control (n=84), unblinded. The app is self-guided and incorporates behavioral relaxation activities, mood tracking and thought challenging, and minigames. Participants completed the Hospital Anxiety and Depression Scale online at baseline and every fortnight. Results: At week 6, the primary end point, there was evidence that the Feel Stress Free app reduced depression symptoms (mean difference −1.56; 95% CI −2.67 to −0.44; P=.006) but only very weak evidence that it reduced anxiety symptoms (mean difference −1.36; 95% CI −2.93 to 0.21; P=.09). At week 4, there was evidence to support the effectiveness of the intervention for anxiety symptoms (mean difference −1.94; 95% CI −3.11 to −0.77; P=.001) and, though weaker, depression symptoms (mean difference −1.08; 95% CI −2.12 to −0.04; P=.04). At week 6, 83% (34/41) of participants indicated that they were using the app weekly or more frequently. Conclusions: The Feel Stress Free app is a promising mobile intervention for treating symptoms of anxiety and depression in students and overcomes many of the barriers to traditional CBT. Further research is needed to establish its effectiveness at and beyond 6 weeks. Trial Registration: ClinicalTrials.gov NCT03032952; https://clinicaltrials.gov/ct2/show/NCT03032952

1 November 2019 in The Lancet Psychiatry
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GLGemma Lewis
Gemma Lewis
LDLarisa Duffy
Larisa Duffy
AAAnthony Ades
Anthony Ades
RARebekah Amos
Rebekah Amos
RARicardo Araya
Ricardo Araya
GLGlyn Lewis
Glyn Lewis
Depression is usually managed in primary care, but most antidepressant trials are of patients from secondary care mental health services, with eligibility criteria based on diagnosis and severity of depressive symptoms. Antidepressants are now used in a much wider group of people than in previous regulatory trials. We investigated the clinical effectiveness of sertraline in patients in primary care with depressive symptoms ranging from mild to severe and tested the role of severity and duration in treatment response. The PANDA study was a pragmatic, multicentre, double-blind, placebo-controlled randomised trial of patients from 179 primary care surgeries in four UK cities (Bristol, Liverpool, London, and York). We included patients aged 18 to 74 years who had depressive symptoms of any severity or duration in the past 2 years, where there was clinical uncertainty about the benefit of an antidepressant. This strategy was designed to improve the generalisability of our sample to current use of antidepressants within primary care. Patients were randomly assigned (1:1) with a remote computer-generated code to sertraline or placebo, and were stratified by severity, duration, and site with random block length. Patients received one capsule (sertraline 50 mg or placebo orally) daily for one week then two capsules daily for up to 11 weeks, consistent with evidence on optimal dosages for efficacy and acceptability. The primary outcome was depressive symptoms 6 weeks after randomisation, measured by Patient Health Questionnaire, 9-item version (PHQ-9) scores. Secondary outcomes at 2, 6 and 12 weeks were depressive symptoms and remission (PHQ-9 and Beck Depression Inventory-II), generalised anxiety symptoms (Generalised Anxiety Disorder Assessment 7-item version), mental and physical health-related quality of life (12-item Short-Form Health Survey), and self-reported improvement. All analyses compared groups as randomised (intention-to-treat). The study is registered with EudraCT, 2013-003440-22 (protocol number 13/0413; version 6.1) and ISRCTN, ISRCTN84544741, and is closed to new participants. Between Jan 1, 2015, and Aug 31, 2017, we recruited and randomly assigned 655 patients-326 (50%) to sertraline and 329 (50%) to placebo. Two patients in the sertraline group did not complete a substantial proportion of the baseline assessment and were excluded, leaving 653 patients in total. Due to attrition, primary outcome analyses were of 550 patients (266 in the sertraline group and 284 in the placebo group; 85% follow-up that did not differ by treatment allocation). We found no evidence that sertraline led to a clinically meaningful reduction in depressive symptoms at 6 weeks. The mean 6-week PHQ-9 score was 7·98 (SD 5·63) in the sertraline group and 8·76 (5·86) in the placebo group (adjusted proportional difference 0·95, 95% CI 0·85-1·07; p=0·41). However, for secondary outcomes, we found evidence that sertraline led to reduced anxiety symptoms, better mental (but not physical) health-related quality of life, and self-reported improvements in mental health. We observed weak evidence that depressive symptoms were reduced by sertraline at 12 weeks. We recorded seven adverse events-four for sertraline and three for placebo, and adverse events did not differ by treatment allocation. Three adverse events were classified as serious-two in the sertraline group and one in the placebo group. One serious adverse event in the sertraline group was classified as possibly related to study medication. Sertraline is unlikely to reduce depressive symptoms within 6 weeks in primary care but we observed improvements in anxiety, quality of life, and self-rated mental health, which are likely to be clinically important. Our findings support the prescription of SSRI antidepressants in a wider group of participants than previously thought, including those with mild to moderate symptoms who do not meet diagnostic criteria for depression or generalised anxiety disorder. National Institute for Health Research.

1 February 2019 in The Lancet Child & Adolescent Health
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MIMadeleine Irish
Madeleine Irish
FSFrancesca Solmi
Francesca Solmi
Becky MarsBecky Mars
Becky Mars
MKMichael King
Michael King
GLGlyn Lewis
Glyn Lewis
GLGemma Lewis
Gemma Lewis
There are few population-based cohort studies of the emergence, development, and persistence of mental health problems in sexual minorities compared with heterosexuals. We compared trajectories of depressive symptoms in sexual-minority adolescents and heterosexual adolescents from when they were aged 10 years to 21 years, and examined self-harm at ages 16 years and 21 years. The study included 4828 adolescents born between April 1, 1991, and Dec 31, 1992, from the Avon Longitudinal Study of Parents and Children birth cohort (Bristol, UK) who reported their sexual orientation when aged 16 years. Depressive symptoms were assessed with the short Mood and Feelings Questionnaire (sMFQ) at seven timepoints between ages 10 years and 21 years. A self-harm questionnaire was completed at ages 16 years and 21 years. Analyses were linear multilevel models with growth curves (depressive symptoms), logistic multilevel models (self-harm in the previous year at ages 16 years and 21 years), and multinomial regression (lifetime self-harm with and without suicidal intent at age 21 years). At age 10 years, depressive symptoms were higher in sexual minorities (mean sMFQ 4·58 [SD 3·59]) than in heterosexuals (3·79 [3·36]) and increased with age to a larger extent. Depressive symptoms increased at each timepoint by 0·31 sMFQ points in hetereosexuals (95% CI 0·27-0·34), and by 0·49 sMFQ points in sexual minorities (0·40-0·59). Sexual-minority adolescents were more likely than heterosexual adolescents to report self-harm in the previous year at ages 16 years and 21 years (adjusted odds ratio 4·23, 95% CI 2·90-6·16), with no evidence that this estimate decreased with age (p=0·80). When aged 21 years, sexual minorities were 4·53 (95% CI 3·02 to 6·78) times more likely to report lifetime self-harm (ie, on at least one previous occasion) with suicidal intent than heterosexuals. Mental health disparities between heterosexuals and sexual minorities are present early in adolescence and increase throughout the school years, persisting to young adulthood. Prevention of these mental health problems and early intervention must be a priority. Medical Research Council, Wellcome Trust.

1 May 2011 in Journal of the American Academy of Child & Adolescent Psychiatry
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Journal Article
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GLGemma Lewis
Gemma Lewis
FRFrances Rice
Frances Rice
GHGordon T. Harold
Gordon T. Harold
SCStephan Collishaw
Stephan Collishaw
ATAnita Thapar
Anita Thapar
Links between maternal and offspring depression symptoms could arise from inherited factors, direct environmental exposure, or shared adversity. A novel genetically sensitive design was used to test the extent of environmental links between maternal depression symptoms and child depression/anxiety symptoms, accounting for inherited effects, shared adversity, and child age and gender. Eight hundred fifty-two families with a child born by assisted conception provided questionnaire data. Mothers and fathers were genetically related or unrelated to the child depending on conception method. Parental depression symptoms were assessed using the Hospital Anxiety and Depression Scale. Child depression/anxiety symptoms were assessed using the Short Mood and Feelings questionnaire and six items tapping generalized anxiety disorder symptoms. Associations between maternal and child symptoms were examined separately for genetically unrelated and related mother-child pairs, adjusting for three measurements of shared adversity: negative life events, family income, and socioeconomic status. Analyses were then run separately for boys and girls and for children and adolescents, and the role of paternal depression symptoms was also examined. Significant associations between parent and child symptoms were found for genetically unrelated mother-child (r = 0.32, p < .001) and father-child (r = 0.17, p < .05) pairs and genetically related mother-child (r = 0.31, p < .001) and father-child (r = 0.23, p < .001) pairs and were not explained by the shared adversity measurements. Environmental links were present for children and adolescents and were stronger for girls. The transmission of depression symptoms is due in part to environmental processes independent of inherited effects and is not accounted for by shared adversity measurements. Girls may be more sensitive to the negative effects of maternal depression symptoms than boys through environmental processes.