Early effects of antidepressants on emotional processing

Introduction: The mechanisms of action of antidepressants at the system level remain mainly unresolved. Antidepressants rapidly modulate emotional processing, enhancing processing of positive versus negative information, but this has been mostly demonstrated in healthy subjects and using fairly simple, controlled emotional stimuli such as emotional faces. Aim of the study: The aim of the studies of this thesis was to shed light on early antidepressant effects on emotional processing both in healthy subjects, avoiding the confounding effect of depressed mood, and in treatment-seeking depressed patients at an early stage of treatment, to elude the confounding effect of improved mood. The studies specifically aimed to reveal antidepressant effects on self-referential processing, a core factor in psychopathology of depression, and to investigate whether/how antidepressants modulate processing of complex, dynamic emotional stimuli resembling daily-life emotional situations. Methods: In Study 1 (experiments I and II), an open-label study of 30 healthy volunteers, half of the subjects received mirtazapine 15 mg two hours prior to functional magnetic resonance imaging (fMRI), and the other half was scanned without medication as a control group. Study 2 (experiments III and IV) was a double-blind, placebo-controlled study where 32 treatment-seeking depressed patients were randomized to receive escitalopram 10 mg or placebo for one week, after which fMRI was performed. In experiments I and III, neural responses to positive and negative self-referential adjectives as well as a neutral control task were assessed. In experiments II and IV participants listened to spoken emotional narratives and neural responses to the emotional content of the narratives were assessed. Results: Both mirtazapine in healthy subjects and escitalopram in depressed patients modulated self-referential processing. Mirtazapine attenuated responses to both positive and negative self-referential words in the anterior cortical midline structures (CMS, including the medial prefrontal cortex and the anterior cingulate), whereas escitalopram increased processing of positive relative to negative self-referential words. When comparing the placebo group and the escitalopram group from Study 2 separately with the healthy controls from Study 1, depressed patients receiving placebo had decreased responses of the anterior CMS to positive versus negative self-referential words, whereas no differences were found between the escitalopram group and healthy controls, implicating normalization of the negative bias in depressed patients receiving escitalopram. Both mirtazapine and escitalopram also modulated brain responses to spoken emotional narratives. Mirtazapine was found to modulate dynamic functional connectivity (measured with seed-based phase synchronization) of large-scale brain circuits, particularly potentiating functional connectivity of the anterior CMS and the limbic regions during positive parts of the narratives. Escitalopram increased synchronization of brain responses (measured with inter-subject correlation, ISC), specifically during positive parts of the narratives. Conclusions: A single dose of mirtazapine in healthy subjects and a one-week treatment with escitalopram in treatment-seeking depressed patients modulated neural responses to emotional information without any concurrent changes in mood. Both antidepressants modulated self-referential processing, a core psychological process in developing and maintaining depression. Escitalopram normalized the negatively biased self-referential processing of depressed patients in the anterior CMS. Both mirtazapine and escitalopram modulated brain responses to spoken emotional narratives, extending the previous findings of antidepressant effects based on simple emotional stimuli to complex, dynamic, every-day like emotional situations. Specifically, potentiated processing measured with novel methods of dynamic functional connectivity and ISC was found in the anterior CMS among other regions during positive emotional content of the narratives. These results suggest that antidepressants rapidly modulate processing of particularly positive emotional and self-referential information in the anterior CMS. This may be important for their later therapeutic effect.Johdanto: Masennuslääkkeiden vaikutusmekanismeja systeemitasolla tunnetaan yhä heikosti. Niiden tiedetään vaikuttavan nopeasti tunteiden prosessointiin voimistamalla positiivisen informaation prosessointia negatiiviseen verrattuna. Tämä vaikutus on kuitenkin osoitettu lähinnä terveillä koehenkilöillä sekä käyttäen koeasetelmissa yksinkertaisia ärsykkeitä, kuten emotionaalisia kasvokuvia. Tavoitteet: Tämän väitöskirjatyön osatutkimusten tavoitteena oli selvittää masennuslääkkeiden varhaisia vaikutuksia tunteiden prosessointiin sekä terveillä koehenkilöillä, välttäen näin masentuneen mielialan sekoittava vaikutus, että masentuneilla potilailla hoidon varhaisessa vaiheessa, välttäen näin korjaantuvan mielialan sekoittava vaikutus. Erityisesti tavoitteena oli tutkia masennuslääkkeiden vaikutusta itseen liittyvään prosessointiin, koska liiallinen keskittyminen omiin, usein negatiivisiin tunteisiin ja ajatuksiin on eräs masennuksen keskeisistä psykologisista ilmiöistä. Lisäksi haluttiin selvittää, kuinka masennuslääkkeet vaikuttavat monimutkaisten, tosielämän emotionaalisia tilanteita muistuttavien ärsykkeiden prosessointiin. Menetelmät: Osatutkimuksessa 1 (koeasetelmat I ja II) puolet 30 terveestä vapaaehtoisesta sai avoimessa tutkimusasetelmassa 15mg mirtatsapiinia kaksi tuntia ennen toiminnallista magneettikuvausta (fMRI) ja puolet kuvattiin verrokkiryhmänä ilman lääkitystä. Osatutkimuksessa 2 (koeasetelmat III ja IV) 32 hoitoon hakeutunutta masennuspotilasta satunnaistettiin kaksois-sokkoutetussa tutkimusasetelmassa saamaan 10mg essitalopraamia tai lumetta viikon verran, jonka jälkeen suoritettiin fMRI-kuvaus. Koeasetelmissa I ja III mitattiin aivovasteita positiivisille ja negatiivisille itseen liittyville adjektiiveille sekä neutraaleille kontrollisanoille. Koeasetelmissa II ja IV koehenkilöt kuuntelivat kuvauksen aikana tunteita herättäviä tarinoita ja tarinoiden tunnesisällön herättämät aivovasteet mitattiin. Tulokset: Sekä mirtatsapiini terveillä koehenkilöillä että essitalopraami masennuspotilailla muokkasi aivovasteita itseen liittyviä sanoja prosessoitaessa. Mirtatsapiini vaimensi sekä positiivisten että negatiivisten sanojen herättämiä vasteita odotetuilla alueilla aivojen keskilinjan kortikaalisten alueiden etuosissa (keskimmäinen etuotsalohko ja etummainen pihtipoimu), kun taas essitalopraami voimisti positiivisten sanojen prosessointia negatiivisiin nähden masennuspotilailla. Kun osatutkimuksen 2 masennuspotilaiden aivovasteita verrattiin lume- ja lääkeryhmässä erikseen osatutkimuksen 1 terveisiin verrokkeihin, havaittiin lumeryhmän reagoivan heikommin positiivisiin sanoihin negatiivisiin nähden, kun taas lääkeryhmän ja terveiden verrokeiden välillä ei ollut eroa. Essitalopraami siis palautti masennuspotilaiden negatiivisesti vääristyneen itseen liittyvän prosessoinnin normaalille, terveelle tasolle. Molemmat masennuslääkkeet muovasivat aivovasteita emotionaalisten tarinoiden tunnesisällölle. Mirtatsapiini vaikutti laaja-alaisesti aivoalueiden välisiin toiminnallisiin yhteyksiin, erityisesti voimistamalla niitä aivojen keskilinja-alueiden etuosassa ja limbisellä alueella tarinoiden positiivisuuden lisääntyessä. Essitalopraami voimisti koehenkilöiden välistä synkroniaa aivovasteissa, erityisesti positiivisen sisällön aikana. Johtopäätökset: Molemmat tutkitut masennuslääkkeet vaikuttivat tunteiden prosessointiin nopeasti, ilman samanaikaista muutosta mielialassa. Essitalopraami normalisoi masennuspotilaiden negatiivisesti vääristynyttä itseen kohdistuvaa prosessointia, jonka ajatellaan olevan tärkeä tekijä masennustilan kehittymisessä ja jatkumisessa. Molemmat tutkitut masennuslääkkeet myös muokkasivat emotionaalisten tarinoiden herättämiä aivovasteita. Tämä tulos on merkittävä lisä aiempiin löydöksiin, koska se osoittaa masennuslääkkeiden muuttavan myös monimutkaisten ja dynaamisten, lähempänä todellisia arkipäivän tunteita herättäviä tilanteita olevien emotionaalisten ärsykkeiden prosessointia. Todetut muutokset voivat olla merkittävässä roolissa myöhemmän kliinisen lääkevasteen kannalta

Masennuslääkkeiden vaikutukset tunteiden käsittelyyn

Vertaisarvioitu. English summaryPeer reviewe

Masennuslääkkeiden vaikutukset tunteiden käsittelyyn

Masennukseen liittyy emotionaalisen tiedon käsittelyn vääristymiä. Masennuspotilaat esimerkiksi muistavat ja tulkitsevat ympäristön tapahtumia negatiivisesti vääristyneellä tavalla. Masennuksen eri hoitomuodot pyrkivät muovaamaan näitä vääristymiä. Myös masennuslääkkeet vaikuttavat emotionaalisen tiedon käsittelyyn jo ennen kuin masennusoireet väistyvät. Masennuslääkkeet heikentävät aivojen tunneverkoston keskeisten alueiden reaktiivisuutta negatiivisiin ärsykkeisiin ja voimistavat reaktiivisuutta positiivisiin ärsykkeisiin. Dorsolateraalisen etuaivokuoren aktiivisuus voimistuu, mikä viittaa parantuneeseen tunteiden säätelyyn. Masennuslääkkeet vaikuttavat myös laaja-alaisten aivoverkostojen toiminnallisiin yhteyksiin. Nämä varhaiset emotionaalisen prosessoinnin muutokset vaikuttavat ennustavan viikkoja myöhemmin saavutettavaa hoitovastetta. Emotionaalisen tiedonkäsittelyn muutokset saattaisivat siis toimia hoidon valintaa ohjaavina ennustetekijöinä, joita ei nykyisin ole kliinisessä käytössä. Masennuslääkkeiden vaikutusmekanismien tunteminen systeemitasolla on tärkeää myös uusien hoitomuotojen kehittämisen kannalta.</p

Escitalopram enhances synchrony of brain responses during emotional narratives in patients with major depressive disorder

One-week treatment with escitalopram decreases amygdala responses to fearful facial expressions in depressed patients, but it remains unknown whether it also modulates processing of complex and freely processed emotional stimuli resembling daily life emotional situations. Inter-subject correlation (ISC) offers a means to track brain activity during complex, dynamic stimuli in a model-free manner. Twenty-nine treatment-seeking patients with major depressive disorder were randomized in a double-blind study design to receive either escitalopram or placebo for one week, after which functional magnetic resonance imaging (fMRI) was performed. During fMRI the participants listened to spoken emotional narratives. Level of ISC between the escitalopram and the placebo group was compared across all the narratives and separately for the episodes with positive and negative valence. Across all the narratives, the escitalopram group had higher ISC in the default mode network of the brain as well as in the fronto-temporal narrative processing regions, whereas lower ISC was seen in the middle temporal cortex, hippocampus and occipital cortex. Escitalopram increased ISC during positive parts of the narratives in the precuneus, medial prefrontal cortex, anterior cingulate and fronto-insular cortex, whereas there was no significant synchronization in brain responses to positive vs negative events in the placebo group. Increased ISC may imply improved emotional synchronization with others, particularly during observation of positive events. Further studies are needed to test whether this contributes to the later therapeutic effect of escitalopram.Peer reviewe

Short-term escitalopram treatment normalizes aberrant self-referential processing in major depressive disorder

Background: Increased self-focus and negative self-concept play an important role in depression. Antidepressants influence self-referential processing in healthy volunteers, but their function in self-processing of depressed patients remains unknown. Methods: Thirty-two depressed patients were randomly allocated to receive either escitalopram 10 mg or placebo for one week. After one week, neural responses to positive and negative self-referential adjectives and neutral control stimuli were assessed with functional magnetic resonance imaging. A group of matched healthy volunteers served as a control group. Results: Escitalopram decreased responses of medial fronto-parietal regions to self-referential words relative to non-emotional control stimuli, driven by increased responses to the control condition. Escitalopram also increased responses in the pre-defined region of the medial prefrontal cortex (MPFC) and the anterior cingulate cortex (ACC) to positive relative to negative words. Importantly, the changes in neural responses occurred before any effect on depressive symptoms, implying a direct effect of escitalopram. Furthermore, the placebo group had decreased responses of the MPFC and the ACC to positive self-referential processing relative to the matched healthy controls. However, neural responses of the escitalopram group and the healthy unmedicated controls were similar. Limitations: Differences between the groups in self-reported depression symptoms and personality traits may have influenced the results. Conclusion: One-week treatment with escitalopram normalized aberrant self-referential processing in depressed patients, shifting the focus from the self to the external environment and potentiating positive self-referential processing. This may be an important factor in mechanism of action of antidepressants.Peer reviewe

A single dose of mirtazapine attenuates neural responses to self-referential processing

Increased self-focus is a core factor in the psychopathology of depression. Cortical midline structures (CMS) are implicated in the neurobiology of self, depression and antidepressant treatment response. Mirtazapine, an antidepressant that increases serotonin and norepinephrine release, enhances processing of positive and attenuates processing of negative emotional information in healthy volunteers after a single dose. These early changes, which are opposite to the negative information bias in depression, may be important for the therapeutic effect of mirtazapine. It nevertheless remains unresolved whether/how mirtazapine specifically influences processing of self-referential emotional information. Half of the healthy volunteers (n=15/30) received a single dose of mirtazapine, in an open-label design, two hours before functional magnetic resonance imaging (fMRI), and the other half was scanned as a control group without medication. During fMRI the participants categorized positive and negative self-referential adjectives. Mirtazapine attenuated responses to self-referential processing in the medial prefrontal cortex and the anterior cingulate cortex. Mirtazapine further decreased responses to positive self-referential processing in the posterior cingulate cortex and parietal cortex. These decreased responses of the CMS suggest that mirtazapine may rapidly improve the ability of the CMS to down-regulate self-referential processing. In depressed patients, this could lead to decreased self-focus and rumination, contributing to the antidepressant effect.Peer reviewe

Escitalopram enhances synchrony of brain responses during emotional narratives in patients with major depressive disorder

One-week treatment with escitalopram decreases amygdala responses to fearful facial expressions in depressed patients, but it remains unknown whether it also modulates processing of complex and freely processed emotional stimuli resembling daily life emotional situations. Inter-subject correlation (ISC) offers a means to track brain activity during complex, dynamic stimuli in a model-free manner.& nbsp; Twenty-nine treatment-seeking patients with major depressive disorder were randomized in a double-blind study design to receive either escitalopram or placebo for one week, after which functional magnetic resonance imaging (fMRI) was performed. During fMRI the participants listened to spoken emotional narratives. Level of ISC between the escitalopram and the placebo group was compared across all the narratives and separately for the episodes with positive and negative valence.& nbsp; & nbsp;Across all the narratives, the escitalopram group had higher ISC in the default mode network of the brain as well as in the fronto-temporal narrative processing regions, whereas lower ISC was seen in the middle temporal cortex, hippocampus and occipital cortex. Escitalopram increased ISC during positive parts of the narratives in the precuneus, medial prefrontal cortex, anterior cingulate and fronto-insular cortex, whereas there was no significant synchronization in brain responses to positive vs negative events in the placebo group. Increased ISC may imply improved emotional synchronization with others, particularly during observation of positive events. Further studies are needed to test whether this contributes to the later therapeutic effect of escitalopram

The Effect of Personality on Daily Life Emotional Processes

Peer reviewe

Single dose of mirtazapine modulates whole-brain functional connectivity during emotional narrative processing

The link between neurotransmitter-level effects of antidepressants and their clinical effect remain poorly understood. A single dose of mirtazapine decreases limbic responses to fearful faces in healthy subjects, but it is unknown whether this effect applies to complex emotional situations and dynamic connectivity between brain regions. Thirty healthy volunteers listened to spoken emotional narratives during functional magnetic resonance imaging (fMRI). In an open-label design, 15 subjects received 15 mg of mirtazapine two hours prior to fMRI while 15 subjects served as a control group. We assessed the effects of mirtazapine on regional neural responses and dynamic functional connectivity associated with valence and arousal. Mirtazapine attenuated responses to unpleasant events in the right fronto-insular cortex, while modulating responses to arousing events in the core limbic regions and the cortical midline structures (CMS). Mirtazapine decreased responses to unpleasant and arousing events in sensorimotor areas and the anterior CMS implicated in self-referential processing and formation of subjective feelings. Mirtazapine increased functional connectivity associated with positive valence in the CMS and limbic regions. Mirtazapine triggers large-scale changes in regional responses and functional connectivity during naturalistic, emotional stimuli. These span limbic, sensorimotor, and midline brain structures, and may be relevant to the clinical effectiveness of mirtazapine.Peer reviewe

Effect of remdesivir post hospitalization for COVID-19 infection from the randomized SOLIDARITY Finland trial

We report the first long-term follow-up of a randomized trial (NCT04978259) addressing the effects of remdesivir on recovery (primary outcome) and other patient-important outcomes one year after hospitalization resulting from COVID-19. Of the 208 patients recruited from 11 Finnish hospitals, 198 survived, of whom 181 (92%) completed follow-up. At one year, self-reported recovery occurred in 85% in remdesivir and 86% in standard of care (SoC) (RR 0.94, 95% CI 0.47-1.90). We infer no convincing difference between remdesivir and SoC in quality of life or symptom outcomes (p > 0.05). Of the 21 potential long-COVID symptoms, patients reported moderate/major bother from fatigue (26%), joint pain (22%), and problems with memory (19%) and attention/concentration (18%). In conclusion, after a one-year follow-up of hospitalized patients, one in six reported they had not recovered well from COVID-19. Our results provide no convincing evidence of remdesivir benefit, but wide confidence intervals included possible benefit and harm.Peer reviewe