Neural correlates of verbal recognition memory in obese adults with and without major depressive disorder.

BACKGROUND: Obesity and major depressive disorder (MDD) independently contribute to memory impairment. Little is known about shared neural mechanisms that may result in the cognitive impairment experienced by these populations. This study's aim was to determine how obesity impacts neural activity during a verbal recognition memory task in individuals both with and without MDD. METHODS: Functional magnetic resonance imaging was employed to examine whether differences in neural activation patterns would be seen across three groups during the Warrington's Recognition Memory Test. Three study groups are reported: 20 subjects with obesity but without MDD (bariatric controls), 23 subjects with past or current MDD and obesity, and 20 normal BMI controls (healthy controls). RESULTS: Three-group conjunction analyses indicated that overlapping neural regions were activated during both encoding and retrieval processes across all groups. However, second-level 2-group t-contrasts indicated that neural activation patterns differed when comparing healthy and bariatric controls, and when comparing bariatric controls and bariatric MDD participants. DISCUSSION: Results indicate that obesity in conjunction with MDD confers a subtle impact on neural functioning. Given high rates of obesity and MDD comorbidity, and the role of cognition on ability to return to premorbid level of functioning, this association should inform treatment decisions.

The impact of obesity on neuropsychological functioning in adults with and without major depressive disorder.

BACKGROUND: Evidence suggests obesity exerts a negative impact on cognition. Major Depressive Disorder (MDD) is also linked to problems in cognitive functioning. Obesity is highly prevalent in individuals with MDD and is linked to a failure to return to a full level of functioning. The study's objective was to investigate the effect of obesity on cognitive impairment in participants with MDD. METHODS: This study compared cognitive performance in obese individuals with MDD and two control populations (obese individuals without a psychiatric illness and non-obese controls). A standardized battery of neuropsychological tests specifically designed to assess performance in declarative memory, executive functioning, processing speed and attention was administered. Mood ratings, physical measurements, nutritional and health questionnaires were also completed. RESULTS: We observed a consistent pattern across measures of memory, executive functioning, attention and processing speed. Whereas healthy controls performed better than both bariatric groups across the majority of measures administered, bariatric controls tended to outperform bariatric MDD patients. LIMITATIONS: The overall sample size of our study was small and thus largely explorative in nature. However, it provides compelling results (while controlling for extraneous variables such as medication load, nutritional status and common metabolic comordidities) that strongly urges for further investigation and study replication with larger sample sizes. CONCLUSIONS: We found obesity has a subtle impact on cognition in obese individuals, and when obesity is present in individuals with MDD, this impact may be significant. It is important to minimize all modifiable variables that can add to cognitive burden in this population.

Effect of obesity on cognition in adults with and without a mood disorder: study design and methods.

INTRODUCTION: Obesity is a common medical illness that is increasingly recognised as conferring risk of decline in cognitive performance, independent of other comorbid medical conditions. Individuals with mood disorders (bipolar disorder (BD) or major depressive disorder (MDD)) display an increased prevalence of both obesity and risk factors for cardiovascular diseases. Moreover, BD and MDD are associated with impairment in cognitive functioning across multiple domains. The independent contribution of obesity to cognitive decline in this population has not been explored. This study examines the impact of obesity on cognition by comparing neuropsychological performance in obese individuals, with or without a mood disorder before and after undergoing bariatric surgery. METHODS AND ANALYSIS: This study compares measures of declarative memory, executive functioning and attention in obese individuals (body mass index >35 kg/m(2)) with BD or MDD, and 2 control populations (obese individuals without a psychiatric illness and healthy non-obese controls) prior to and following bariatric surgery. Participants (ages 18-60) receive a psychiatric diagnosis via the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; SCID). Mood ratings, physical measurements, nutritional and health questionnaires are also administered. A standardised battery of neuropsychological tests aimed at establishing performance in areas of declarative memory, executive functioning and attention are administered. Warrington's Recognition Memory Task (RMT) and an N-Back Task are performed in a 3 T functional MRI to investigate patterns of neural activation during cognitive performance. Additionally, anatomical MRI data are obtained to investigate potential changes in neural structures. Baseline data will be analysed for between-group differences and later compared with postsurgical data to investigate cognitive change. ETHICS AND DISSEMINATION: This study has been approved by the Hamilton Integrated Research Ethics Board (09-3254). Results will be available in peer-reviewed scientific publications and scientific meetings presentations, and released in lay form to media.

Olanzapine-induced weight gain in patients with bipolar I disorder: a meta-analysis.

OBJECTIVE: The weight impact produced by the atypical antipsychotic olanzapine has been explored in meta-analyses focusing on patients with schizophrenia. However, outcomes identified for schizophrenia patients cannot always be generalized to patients with bipolar disorder. This study aims to quantitatively estimate the impact of olanzapine on the weight of patients with bipolar disorder. DATA SOURCES: EMBASE, Medline, and PsycINFO were searched using the keywords olanzapine AND (bipolar OR acute mania) in conjunction with (weight gain OR weight increase) (last search: October 2010, with no restrictions on dates of publication). English language was used as a restriction. STUDY SELECTION: The search identified 110 articles for review. The inclusion criteria for the chosen studies were a diagnosis of bipolar disorder, the presence of an olanzapine monotherapy group, a comparator placebo or monotherapy group, and mean weight gain and/or incidences of weight gain data. This process identified 13 studies for inclusion. DATA EXTRACTION: The primary outcome measure was the mean weight change between olanzapine monotherapy and comparator monotherapy, reported in kilograms. Standard deviation was extracted directly from studies when possible and imputed for 3 studies. The secondary outcome measure was the reported incidences of ≥ 7% weight gain. DATA SYNTHESIS: The mean difference in weight gain was calculated for the continuous data of the primary outcome. Olanzapine monotherapy was associated with more weight gain when compared to placebo (mean difference = 2.10 kg; 95% CI, 1.16-3.05; P < .001) and other bipolar monotherapy (mean difference = 1.34 kg; 95% CI, 0.95-1.72; P < .001). Odds ratio analysis of the dichotomous secondary outcome also showed more weight gain with olanzapine monotherapy compared to placebo (odds ratio [OR] = 10.12; 95% CI, 1.93-53.14; P = .006) and other bipolar monotherapy (OR = 2.09; 95% CI, 1.27-3.44; P = .004). CONCLUSIONS: Currently available data suggest that olanzapine is associated with significant weight gain in bipolar patients. Issues related to side effect profiles and their impact on treatment compliance and physical health outcomes need to be considered when selecting pharmacotherapy.