Cognitive impairment in remitted and non-remitted depressive patients: A follow-up comparison between first and recurrent episodes

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Abstract

Cognitive impairment is a core symptom of depressive disorders associated with poor social function. New research is needed to analyze depression-related symptoms in cognitive impairment and to observe if they are reversible or not during clinical remission in patients with or without previous episodes. None of the previous studies has analyzed the differences between first and recurrent episodes in a long-term follow-up study related with remission state. The aim of our study was to compare cognitive performance and assess the impact of previous depressive episodes in a sample of patients in acute phase and in remission six month later. 79 depressive patients were assessed at baseline. The instruments used for clinical and cognitive assessment were: Hamilton Depression Rating Scale, Mini-Mental State Examination and the Clinical Global Impression Rating Scales, Trail Making Test parts A and B, Digital Span subtest of WAIS, Stroop Colour Word Test, Tower of London, Controlled Verbal Fluency Task, Semantic Verbal Fluency and Finger Tapping Test. A repeated measures MANCOVA with education as covariate was used. No differences were found at baseline between first episode and recurrent depressive patients. At six month, remitted patients scored significant better in TMT-A, TMT-B, Animals and Tower of London total time. Remitted first depressive patients scored significant worse than remitted recurrent depressive patients. The main finding of the study is the effect of remission on cognitive function despite previous episodes. However first episode remitted patients seemed to have poor access to long term memory than recurrent remitted patients.

Introduction

Depression is a disorder associated with impairment of cognitive function (Bora et al., 2013, McIntyre et al., 2013). Cognition across a variety of domains is impaired, including executive functioning. These deficits are associated with poor social function (Rock et al., 2013). The nature and specificity of these cognitive impairments remains unclear. Some authors have argued that difficulties with social function are best explained in the context of the commonly observed cognitive deficits (Roca et al., 2015). Others have characterized these difficulties in terms of ‘social cognition’ deficits (Ladegaard et al., 2014, Weightman et al., 2014), though it is unclear whether social cognition is a qualitatively distinct, modular component of cognition (Aboulafia-Brakha et al., 2011).

Cognitive disturbances appears to be impacted by a variety of clinical factors, including severity, comorbidity, subtype of depression and duration of illness (Hasselbalch et al., 2011, McDermott and Ebmeier, 2009). Attention, visual learning, verbal memory and executive functions are significantly impaired in major depressive disorder patients without previous depressive episodes compared to healthy controls (Lee et al., 2012). Cognitive deficits leading to poor psychomotor speed and memory functioning were associated with clinical state, whereas attention and executive functioning are proposed to be likely trait-markers of the disease (Lee et al., 2012). Cognitive deficits seems to be more severe in recurrent episodes (Gorwood and Corruble, 2008, Herrmann et al., 2007). In a sample of 1140 depressive patients Gorwood et al. (2014) reported that after 6–8 weeks of treatment, after controlling for age, educational level and professional activity, ‘psychomotor speed’ was correlated with the number of previous episodes in patients with clinical remission. However, a recent meta-analysis did not report significantly worse performance between samples including both first episode (FE) and recurrent episodes (RE) compared with studies solely examining patients in their first episode (Lee et al., 2012).

The relation between cognitive disturbances and the course of depression is a crucial question to understand the conceptual models of the disease (Bhardwaj et al., 2010, Preiss et al., 2009). New research is needed to analyze depression-related symptoms in cognitive impairment and to observe if they are reversible or not during clinical remission in patients with or without previous depressive episodes. None of the related papers has analyzed the differences between FE or RE depressive patients in a long-term follow-up study and related with remission state.

Our study compares cognitive performance in a sample of patients in acute status and six months later, to determine the presence of a different clinical pattern of cognitive impairment associated to the number of previous depressive episodes and how remission could mediate it. We hypothesized that number of past episodes would affect cognitive performance but this effect may lessen as a function of clinical remission.

Section snippets

Design and setting

An observational longitudinal cohort study was designed to contact as many patients as possible. Patients were individually recruited and included consecutively by clinical psychiatrists from four health care centres. Inclusion criteria were 1) diagnosis of DSM-IV-TR Major Depressive Disorder (MDD), 2) age between 18 and 55 years, 3) at least a total score of 17 on Hamilton Depression Rating Scale, 4) be able to read and understand native language, and 5) have signed informed consent. Exclusion

Results

The sample was composed of seventy nine depressive patients, 26 met first episode and 53 recurrent depression criteria. The sample was mainly composed of middle-aged (X¯=46.11, SD=8.28) women (78.48%), married (62.03%) and living accompanied (83.56%), employed (62.03%), with at least primary education studies (58.24%). At baseline mean HRSD total score for the whole sample was 23.43 (SD=4.46), while MMSE mean score was 1.21(SD=0.5), and CGI Severity mean score was 3.92 (SD=0.86). Most of the

Discussion

The main result of our study is the positive impact of remission on cognitive impairment in depressive patients regardless of the number of previous episodes after six months of treatment. Remitted patients scored significantly better than non-remitted in nine of the cognitive tasks used in our study. When remitted FE depressive patients were compared with remitted RE depressive patients no statistically differences were found except for SVF scale.

The impact of clinical remission was remarkable

Role of funding source

None.

Contributors

MR, SM and MG designed the study and wrote the protocol. MR, ELN, MV managed the literature searches. SM and MV assess the patients included in the study. MR and ELN undertook the statistical analysis. MR, ELN, MGT, JGC and JH wrote the first draft of the manuscript. All authors contributed to and have approved the final manuscript.

Conflict of interest

Dr. Roca, Ms. Monzón, Ms. Vives, Dr. García-Toro and Dr. Gili report grants from the Instituto de Salud Carlos III (Institute of Health Carlos III) of the Ministry of Economy and Competitiveness (Spain) and the European Union ERDF funds, during the conduct of the study; Dr. Roca reports personal fees from Eli Lilly, Servier and Pfizer; and grants and personal fees from Lundbeck and Jannsen, outside the submitted work. Dr. García-Campayo reports personal fees from Pfizer, Eli Lilly, Rovi and

Acknowledgements

This project has been funded by a Grant from the Instituto de Salud Carlos III (Institute of Health Carlos III) (FIS no. PI08 1270) of the Ministry of Economy and Competitiveness (Spain), and co-financed with European Union ERDF Funds.

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