Assessing anhedonia in depression: Potentials and pitfalls

Adida, 2011, Trait-related decision-making impairment in the three phases of bipolar disorder, Biol. Psychiatry, 70, 357, 10.1016/j.biopsych.2011.01.018 Aguilar, 2009, Neurobiological mechanisms of the reinstatement of drug-conditioned place preference, Brain Res. Rev., 59, 253, 10.1016/j.brainresrev.2008.08.002 Alloy, 2008, Behavioral approach system and behavioral inhibition system sensitivities and bipolar spectrum disorders: prospective prediction of bipolar mood episodes, Bipolar Disord., 10, 310, 10.1111/j.1399-5618.2007.00547.x Barbano, 2007, Opioids for hedonic experience and dopamine to get ready for it, Psychopharmacology (Berl)., 191, 497, 10.1007/s00213-006-0521-1 Bari, 2010, Serotonin modulates sensitivity to reward and negative feedback in a probabilistic reversal learning task in rats, Neuropsychopharmacology, 35, 1290, 10.1038/npp.2009.233 Bechara, 1994, Insensitivity to future consequences following damage to human prefrontal cortex, Cognition, 50, 7, 10.1016/0010-0277(94)90018-3 Beck, 1961, An inventory for measuring depression, Arch. Gen. Psychiatry, 4, 561, 10.1001/archpsyc.1961.01710120031004 Beck, 2010, Primary and secondary rewards differentially modulate neural activity dynamics during working memory, PLoS One, 5, e9251, 10.1371/journal.pone.0009251 Berlin, 1998, Measures of anhedonia and hedonic responses to sucrose in depressive and schizophrenic patients in comparison with healthy subjects, Eur. Psychiatry, 13, 303, 10.1016/S0924-9338(98)80048-5 Bevins, 2005, Novelty reward as a measure of anhedonia, Neurosci. Biobehav. Rev., 29, 707, 10.1016/j.neubiorev.2005.03.013 Bourke, 2010, Processing of facial emotion expression in major depression: a review, Aust. N. Z. J. Psychiatry, 44, 681, 10.3109/00048674.2010.496359 Budhani, 2005, Response reversal and children with psychopathic tendencies: success is a function of salience of contingency change, J. Child Psychol. Psychiatry, 46, 972, 10.1111/j.1469-7610.2004.00398.x Campbell-Sills, 2004, Psychometric evaluation of the behavioral inhibition/behavioral activation scales in a large sample of outpatients with anxiety and mood disorders, Psychol. Assess., 16, 244, 10.1037/1040-3590.16.3.244 Capuron, 2012, Dopaminergic mechanisms of reduced basal ganglia responses to hedonic reward during interferon alfa administration, Arch. Gen. Psychiatry, 69, 1044, 10.1001/archgenpsychiatry.2011.2094 Carr, 1983, Conditioned place preference from intra-accumbens but not intra-caudate amphetamine injections, Life Sci., 33, 2551, 10.1016/0024-3205(83)90165-0 Carver, 1994, Behavioral inhibition, behavioral activation, and affective responses to impending reward and punishment: the BIS/BAS scales, J. Personal. Soc. Psychol., 67, 319, 10.1037/0022-3514.67.2.319 Chapman, 1976, Scales for physical and social anhedonia, J. Abnorm. Psychol., 85, 374, 10.1037/0021-843X.85.4.374 Chase, 2013, Dissociable patterns of abnormal frontal cortical activation during anticipation of an uncertain reward or loss in bipolar versus major depression, Bipolar Disord., 15, 839, 10.1111/bdi.12132 Christensen, 2011, Biomarkers of anhedonic-like behavior, antidepressant drug refraction, and stress resilience in a rat model of depression, Neuroscience, 196, 66, 10.1016/j.neuroscience.2011.08.024 Clark, 1984, Seven-month clinical outcome of anhedonic and normally hedonic depressed inpatients, Am. J. Psychiatry, 141, 1216, 10.1176/ajp.141.10.1216 Cléry-Melin, 2011, Why don't you try harder? An investigation of effort production in major depression, PLoS One, 6, e23178, 10.1371/journal.pone.0023178 Cohen, 2009, Neuroelectric signatures of reward learning and decision-making in the human nucleus accumbens, Neuropsychopharmacology, 34, 1649, 10.1038/npp.2008.222 Collier, 2013, The utility of the zebrafish model in conditioned place preference to assess the rewarding effects of drugs, Behav. Pharmacol., 24, 375, 10.1097/FBP.0b013e328363d14a Crean, 2000, Reward discounting as a measure of impulsive behavior in a psychiatric outpatient population, Exp. Clin. Psychopharmacol., 8, 155, 10.1037/1064-1297.8.2.155 Delgado, 2000, Tracking the hemodynamic responses to reward and punishment in the striatum, J. Neurophysiol., 84, 3072, 10.1152/jn.2000.84.6.3072 Der-Avakian, 2012, The neurobiology of anhedonia and other reward-related deficits, Trends Neurosci., 35, 68, 10.1016/j.tins.2011.11.005 Der-Avakian, 2013, Assessment of reward responsiveness in the response bias probabilistic reward task in rats: implications for cross-species translational research, Transl. Psychiatry, 3, e297, 10.1038/tp.2013.74 Dichter, 2010, Unipolar depression does not moderate responses to the Sweet Taste Test, Depress. Anxiety, 27, 859, 10.1002/da.20690 Dillon, 2008, Dissociation of neural regions associated with anticipatory versus consummatory phases of incentive processing, Psychophysiology, 45, 36 Dombrovski, 2012, The temptation of suicide: striatal gray matter, discounting of delayed rewards, and suicide attempts in late-life depression, Psychol. Med., 42, 1203, 10.1017/S0033291711002133 Duman, 2010, Models of depression, Vitam. Horm., 82, 1, 10.1016/S0083-6729(10)82001-1 Dunlop, 2007, The role of dopamine in the pathophysiology of depression, Arch. Gen. Psychiatry, 64, 327, 10.1001/archpsyc.64.3.327 Elliott, 1997, Abnormal response to negative feedback in unipolar depression: evidence for a diagnosis specific impairment, J. Neurol. Neurosurg. Psychiatry, 63, 74, 10.1136/jnnp.63.1.74 Fawcett, 1983, Assessing anhedonia in psychiatric patients, Arch. Gen. Psychiatry, 40, 79, 10.1001/archpsyc.1983.01790010081010 Fehnel, 2004, The development and psychometric evaluation of the Motivation and Energy Inventory (MEI), Qual. Life Res., 13, 1321, 10.1023/B:QURE.0000037502.64077.4d Feinberg, 1986, Facial discrimination and recognition in in schizophrenia and affective disorders, Arch. Gen. Psychiatry, 43, 276, 10.1001/archpsyc.1986.01800030094010 Feja, 2014, Ventral medial prefrontal cortex inactivation impairs impulse control but does not affect delay-discounting in rats, Behav. Brain Res., 264, 230, 10.1016/j.bbr.2014.02.013 Forbes, 2009, Altered striatal activation predicting real-world positive affect in adolescent major depressive disorder, Am. J. Psychiatry, 166, 64, 10.1176/appi.ajp.2008.07081336 Gard, 2007, Anhedonia in schizophrenia: distinctions between anticipatory and consummatory pleasure, Schizophr. Res., 93, 253, 10.1016/j.schres.2007.03.008 Gard, 2006, Anticipatory and consummatory components of the experience of pleasure: a scale development study, J. Res. Pers., 40, 1086, 10.1016/j.jrp.2005.11.001 Gooding, 2014, The assessment of interpersonal pleasure: introduction of the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS) and preliminary findings, Psychiatry Res., 215, 237, 10.1016/j.psychres.2013.10.012 Gooding, 2014, Further validation of the ACIPS as a measure of social hedonic response, Psychiatry Res., 215, 771, 10.1016/j.psychres.2013.11.009 Gradin, 2011, Expected value and prediction error abnormalities in depression and schizophrenia, Brain, 134, 1751, 10.1093/brain/awr059 Green, 1997, Rate of temporal discounting decreases with amount of reward, Mem. Cognit., 25, 715, 10.3758/BF03211314 Gualtieri, 2006, Neurocognition in depression: patients on and off medication versus healthy comparison subjects, J. Neuropsychiatry Clin. Neurosci., 18, 217, 10.1176/jnp.2006.18.2.217 Hamani, 2012, Deep brain stimulation reverses anhedonic-like behavior in a chronic model of depression: role of serotonin and brain derived neurotrophic factor, Biol. Psychiatry, 71, 30, 10.1016/j.biopsych.2011.08.025 Hamilton, 1960, A rating scale for depression, J. Neurol. Neurosurg. Psychiatry, 23, 56, 10.1136/jnnp.23.1.56 Harmer, 2009, Effect of acute antidepressant administration on negative affective bias in depressed patients, Am. J. Psychiatry, 166, 1178, 10.1176/appi.ajp.2009.09020149 Harris, 1997, Failure to change exploration or saccharin preference in rats exposed to chronic mild stress, Physiol. Behav., 63, 91, 10.1016/S0031-9384(97)00425-3 Hasler, 2009, Impairments of probabilistic response reversal and passive avoidance following catecholamine depletion, Neuropsychopharmacology, 34, 2691, 10.1038/npp.2009.95 Hatcher, 1997, Chronic mild stress-induced reductions in saccharin intake depend upon feeding status, J. Psychopharmacol., 11, 331, 10.1177/026988119701100408 Henriques, 2000, Decreased responsiveness to reward in depression, Cog. Emot., 14, 711, 10.1080/02699930050117684 Hewett, 2009, Eight-week, placebo-controlled, double-blind comparison of the antidepressant efficacy and tolerability of bupropion XR and venlafaxine XR, J. Psychopharmacol., 23, 531, 10.1177/0269881108089602 Hinson, 2003, Impulsive decision making and working memory, J. Exp. Psychol. Learn. Mem. Cogn., 29, 298, 10.1037/0278-7393.29.2.298 Horton, 2013, A translational pharmacology approach to understanding the predictive value of abuse potential assessments, Behav. Pharmacol., 24, 410, 10.1097/FBP.0b013e3283644d2e Hundt, 2007, The interaction of reinforcement sensitivity and life events in the prediction of anhedonic depression and mixed anxiety- depression symptoms, Pers. Individ. Dif., 43, 1001, 10.1016/j.paid.2007.02.021 Huston, 2013, What’s conditioned in conditioned place preference, Trends Pharmacol. Sci., 34, 162, 10.1016/j.tips.2013.01.004 Ineichen, 2012, Establishing a probabilistic reversal learning test in mice: evidence for the processes mediating reward-stay and punishment- shift behaviour and for their modulation by serotonin, Neuropharmacology, 63, 1012, 10.1016/j.neuropharm.2012.07.025 Kampov-Polevoy, 2006, Sweet preference predicts mood altering effect of and impaired control over eating sweet foods, Eat. Behav., 7, 181, 10.1016/j.eatbeh.2005.09.005 Kasch, 2002, Behavioral activation and inhibition systems and the severity and course of depression, J. Abnorm. Psychol., 111, 589, 10.1037/0021-843X.111.4.589 Kennedy, 2012, The Canadian Biomarker Integration Network in Depression (CAN-BIND): advances in response prediction, Curr. Pharm. Des., 18, 5976, 10.2174/138161212803523635 Kimura, 2013, The biological effects of acute psychosocial stress on delay discounting, Psychoneuroendocrinology, 38, 2300, 10.1016/j.psyneuen.2013.04.019 Kirby, 1999, Heroin addicts have higher discount rates for delayed rewards than non-drug-using controls, J. Exp. Psychol. Gen., 128, 78, 10.1037/0096-3445.128.1.78 Knutson, 2000, FMRI visualization of brain activity during a monetary incentive delay task, Neuroimage, 12, 20, 10.1006/nimg.2000.0593 Knutson, 2001, Dissociation of reward anticipation and outcome with event-related fMRI, Neuroreport, 12, 3683, 10.1097/00001756-200112040-00016 Knutson, 2008, Neural responses to monetary incentives in major depression, Biol. Psychiatry, 63, 686, 10.1016/j.biopsych.2007.07.023 Kring, 2014, The motivation and pleasure dimension of negative symptoms: neural substrates and behavioral outputs, Eur. Neuropsychopharmacol., 24, 725, 10.1016/j.euroneuro.2013.06.007 Kumar, 2014, Differential effects of acute stress on anticipatory and consummatory phases of reward processing, Neuroscience, 266, 1, 10.1016/j.neuroscience.2014.01.058 Kumar, 2008, Abnormal temporal difference reward-learning signals in major depression, Brain, 131, 2084, 10.1093/brain/awn136 Leppänen, 2006, Emotional information processing in mood disorders: a review of behavioral and neuroimaging findings, Curr. Opin. Psychiatry, 19, 34, 10.1097/01.yco.0000191500.46411.00 Lempert, 2010, Delay discounting and future-directed thinking in anhedonic individuals, J. Behav. Ther. Exp. Psychiatry, 41, 258, 10.1016/j.jbtep.2010.02.003 Leventhal, 2006, Measuring hedonic capacity in depression: a psychometric analysis of three anhedonia scales, J. Clin. Psychol., 62, 1545, 10.1002/jclp.20327 Leventopoulos, 2009, Early deprivation leads to long-term reductions in motivation for reward and 5-HT1A binding and both effects are reversed by fluoxetine, Neuropharmacology, 56, 692, 10.1016/j.neuropharm.2008.12.005 Li, 2013, Resting-state functional connectivity predicts impulsivity in economic decision-making, J. Neurosci., 33, 4886, 10.1523/JNEUROSCI.1342-12.2013 Liu, 2011, Deficits in sustaining reward responses in subsyndromal and syndromal major depression, Prog. Neuropsychopharmacol. Biol. Psychiatry, 35, 1045, 10.1016/j.pnpbp.2011.02.018 Llerena, 2013, The Motivation and Pleasure Scale-Self-Report (MAP-SR): reliability and validity of a self-report measure of negative symptoms, Compr. Psychiatry, 54, 568, 10.1016/j.comppsych.2012.12.001 Marin, 1991, Reliability and validity of the Apathy Evaluation Scale, Psychiatry Res., 38, 143, 10.1016/0165-1781(91)90040-V Martinotti, 2012, Agomelatine versus venlafaxine XR in the treatment of anhedonia in major depressive disorder: a pilot study, J. Clin. Psychopharmacol., 32, 487, 10.1097/JCP.0b013e31825d6c25 McCabe, 2009, Neural representation of reward in recovered depressed patients, Psychopharmacology (Berl)., 205, 667, 10.1007/s00213-009-1573-9 McFarland, 2006, Behavioral activation system deficits predict the six-month course of depression, J. Affect. Disord., 91, 229, 10.1016/j.jad.2006.01.012 McLeish, 2007, Measuring impatience: elicited discount rates and the Barratt Impulsiveness Scale, Pers. Individ. Dif., 43, 553, 10.1016/j.paid.2007.01.002 McClintock, 2010, Association between depression severity and neurocognitive function in major depressive disorder: a review and synthesis, Neuropsychology, 24, 9, 10.1037/a0017336 McClure, 2007, Time discounting for primary rewards, J. Neurosci., 27, 5796, 10.1523/JNEUROSCI.4246-06.2007 McMakin, 2012, Anhedonia predicts poorer recovery among youth with selective serotonin reuptake inhibitor treatment-resistant depression, J. Am. Acad. Child Adolesc. Psychiatry, 51, 404, 10.1016/j.jaac.2012.01.011 Moreau, 1992, Antidepressant treatment prevents chronic unpredictable mild stress-induced anhedonia as assessed by ventral tegmentum self- stimulation behavior in rats, Eur. Neuropsychopharmacol., 2, 43, 10.1016/0924-977X(92)90035-7 Morris, 2006, Midbrain dopamine neurons encode decisions for future action, Nat. Neurosci., 9, 1057, 10.1038/nn1743 Murphy, 2003, Neuropsychological impairment in patients with major depressive disorder: the effects of feedback on task performance, Psychol. Med., 33, 455, 10.1017/S0033291702007018 Muscat, 1992, Reversal of stress-induced anhedonia by the atypical antidepressants, fluoxetine and maprotiline, Psychopharmacology (Berl)., 109, 433, 10.1007/BF02247719 Must, 2013, The Iowa Gambling Task in depression – what have we learned about sub-optimal decision-making strategies?, Front. Psychol., 4, 732, 10.3389/fpsyg.2013.00732 Nakonezny, 2010, Psychometric evaluation of the Snaith–Hamilton pleasure scale in adult outpatients with major depressive disorder, Int. Clin. Psychopharmacol., 25, 328, 10.1097/YIC.0b013e32833eb5ee Nestler, 2010, Animal models of neuropsychiatric disorders, Nat. Neurosci., 13, 1161, 10.1038/nn.2647 Nielsen, 2000, Intracranial self-stimulation and sucrose intake differ as hedonic measures following chronic mild stress: interstrain and interindividual differences, Behav. Brain. Res., 107, 21, 10.1016/S0166-4328(99)00110-2 Ossewaarde, 2011, Two-week administration of the combined serotonin-noradrenaline reuptake inhibitor duloxetine augments functioning of mesolimbic incentive processing circuits, Biol. Psychiatry, 70, 568, 10.1016/j.biopsych.2011.03.041 Papp, 2003, Effect of agomelatine in the chronic mild stress model of depression in the rat, Neuropsychopharmacology, 28, 694, 10.1038/sj.npp.1300091 Papp, 1996, Pharmacological validation of the chronic mild stress model of depression, Eur. J. Pharmacol., 296, 129, 10.1016/0014-2999(95)00697-4 Pechtel, 2013, Blunted reward responsiveness in remitted depression, J. Psychiatr. Res., 47, 1864, 10.1016/j.jpsychires.2013.08.011 Pergadia, 2014, Withdrawal of nicotine blunts reward responsiveness in humans and rats, JAMA Psychiatry, 71, 1238, 10.1001/jamapsychiatry.2014.1016 Pizzagalli, 2005, Toward an objective characterization of an anhedonic phenotype: a signal-detection approach, Biol. Psychiatry, 57, 319, 10.1016/j.biopsych.2004.11.026 Pizzagalli, 2008, Reduced hedonic capacity in major depressive disorder: evidence from a probabilistic reward task, J. Psychiatr. Res., 43, 76, 10.1016/j.jpsychires.2008.03.001 Pizzagalli, 2009, Reduced caudate and nucleus accumbens response to rewards in unmedicated individuals with major depressive disorder, Am. J. Psychiatry, 166, 702, 10.1176/appi.ajp.2008.08081201 Pizzagalli, 2014, Depression, stress and anhedonia: toward a synthesis and integrated model, Ann. Rev. Clin. Psychol., 10, 393, 10.1146/annurev-clinpsy-050212-185606 Porter, 2003, Neurocognitive impairment in drug-free patients with major depressive disorder, Br. J. Psychiatry, 182, 214, 10.1192/bjp.182.3.214 Pulcu, 2014, Temporal discounting in major depressive disorder, Psychol. Med., 44, 1825, 10.1017/S0033291713002584 Ribot, 1896 Richards, 1999, Delay or probability discounting in a model of impulsive behavior: effect of alcohol, J. Exp. Anal. Behav., 71, 121, 10.1901/jeab.1999.71-121 Rizvi, 2015, Development and validation of the Dimensional Anhedonia Rating Scale (DARS) in a community sample and individuals with major depression, Psychiatry Res., 229, 109, 10.1016/j.psychres.2015.07.062 Rothschild, 2014, The relationship between change in apathy and changes in cognition and functional outcomes in currently non-depressed SSRI- treated patients with major depressive disorder, Compr. Psychiatry, 55, 1, 10.1016/j.comppsych.2013.08.008 Salamone, 1994, Nucleus accumbens dopamine release increases during instrumental lever pressing for food but not free food consumption, Pharmacol. Biochem. Behav., 49, 25, 10.1016/0091-3057(94)90452-9 Salamone, 2007, Effort-related functions of nucleus accumbens dopamine and associated forebrain circuits, Psychopharmacology (Berl)., 191, 461, 10.1007/s00213-006-0668-9 Schrader, 1997, Does anhedonia correlate with depression severity in chronic depression, Compr. Psychiatry, 38, 260, 10.1016/S0010-440X(97)90057-2 Schultz, 1998, Predictive reward signal of dopamine neurons, J. Neurophysiol., 80, 1, 10.1152/jn.1998.80.1.1 Schultz, 2013, Updating dopamine reward signals, Curr. Opin. Neurobiol., 23, 229, 10.1016/j.conb.2012.11.012 Schweighofer, 2008, Low-serotonin levels increase delayed reward discounting in humans, J. Neurosci., 28, 4528, 10.1523/JNEUROSCI.4982-07.2008 Sescousse, 2010, The architecture of reward value coding in the human orbitofrontal cortex, J. Neurosci., 30, 13095, 10.1523/JNEUROSCI.3501-10.2010 Sescousse, 2013, Processing of primary and secondary rewards: a quantitative meta-analysis and review of human functional neuroimaging studies, Neurosci. Biobehav. Rev., 37, 681, 10.1016/j.neubiorev.2013.02.002 Sherdell, 2012, Anticipatory pleasure predicts motivation for reward in major depression, J. Abnorm. Psychol., 121, 51, 10.1037/a0024945 Shinohara, 2014, Critical role of cholinergic transmission from the laterodorsal tegmental nucleus to the ventral tegmental area in cocaine- induced place preference, Neuropharmacology, 79, 573, 10.1016/j.neuropharm.2014.01.019 Snaith, 1995, A scale for the assessment of hedonic tone the Snaith–Hamilton Pleasure Scale, Br. J. Psychiatry, 167, 99, 10.1192/bjp.167.1.99 Steele, 2007, Blunted response to feedback information in depressive illness, Brain, 130, 2367, 10.1093/brain/awm150 Stoy, 2012, Hyporeactivity of ventral striatum towards incentive stimuli in unmedicated depressed patients normalizes after treatment with escitalopram, J . Psychopharmacol., 26, 677, 10.1177/0269881111416686 Swainson, 2000, Probabilistic learning and reversal deficits in patients with Parkinson’s disease or frontal or temporal lobe lesions: possible adverse effects of dopaminergic medication, Neuropsychologia, 38, 596, 10.1016/S0028-3932(99)00103-7 Takahashi, 2008, Depressive patients are more impulsive and inconsistent in intertemporal choice behavior for monetary gain and loss than healthy subjects–an analysis based on Tsallis’ statistics, Neuro Endocrinol. Lett., 29, 351 Taylor Tavares, 2008, Neural basis of abnormal response to negative feedback in unmedicated mood disorders, Neuroimage, 42, 1118, 10.1016/j.neuroimage.2008.05.049 Treadway, 2011, Reconsidering anhedonia in depression: lessons from translational neuroscience, Neurosci. Biobehav. Rev., 35, 537, 10.1016/j.neubiorev.2010.06.006 Treadway, 2009, Worth the ‘EEfRT’? The effort expenditure for rewards task as an objective measure of motivation and anhedonia, PLoS One, 4, e6598, 10.1371/journal.pone.0006598 Treadway, 2012, Effort-based decision-making in major depressive disorder: a translational model of motivational anhedonia, J. Abnorm. Psychol., 121, 553, 10.1037/a0028813 Tripp, 1999, Sensitivity to reward frequency in boys with attention deficit hyperactivity disorder, J. Clin. Child Psychol., 28, 366, 10.1207/S15374424jccp280309 Tsankova, 2006, Sustained hippocampal chromatin regulation in a mouse model of depression and antidepressant action, Nat. Neurosci., 9, 519, 10.1038/nn1659 Tso, 2014, Differential hedonic experience and behavioral activation in schizophrenia and bipolar disorder, Psychiatry Res., 219, 470, 10.1016/j.psychres.2014.06.030 Uher, 2008, Measuring depression: comparison and integration of three scales in the GENDEP study, Psychol. Med., 38, 289, 10.1017/S0033291707001730 Uher, 2012, Depression symptom dimensions as predictors of antidepressant treatment outcome: replicable evidence for interest-activity symptoms, Psychol. Med., 42, 967, 10.1017/S0033291711001905 van Zessen, 2012, Activation of VTA GABA neurons disrupts reward consumption, Neuron, 73, 1184, 10.1016/j.neuron.2012.02.016 Vrieze, 2013, Reduced reward learning predicts outcome in major depressive disorder, Biol. Psychiatry, 73, 639, 10.1016/j.biopsych.2012.10.014 Walsh, 2007, A longitudinal functional magnetic resonance imaging study of verbal working memory in depression after antidepressant therapy, Biol. Psychiatry, 62, 1236, 10.1016/j.biopsych.2006.12.022 Warden, 2007, The STAR*D Project results: a comprehensive review of findings, Curr. Psychiatry Rep., 9, 449, 10.1007/s11920-007-0061-3 Waugh, 2008, Motivation for reward as a function of required effort: Dissociating the ‘liking’ from the ‘wanting’ system in humans, Motiv. Emot., 32, 323, 10.1007/s11031-008-9104-2 Willner, 1984, The validity of animal models of depression, Psychopharmacology (Berl)., 83, 1, 10.1007/BF00427414 Willner, 1997, Validity, reliability and utility of the chronic mild stress model of depression: a 10-year review and evaluation, Psychopharmacology (Berl)., 134, 319, 10.1007/s002130050456 Willner, 1987, Reduction of sucrose preference by chronic unpredictable mild stress, and its restoration by a tricyclic antidepressant, Psychopharmacology (Berl)., 93, 358, 10.1007/BF00187257 Willner, 1992, Chronic mild stress-induced anhedonia: a realistic animal model of depression, Neurosci. Biobehav. Rev., 16, 525, 10.1016/S0149-7634(05)80194-0 Willner, 2005, Dopaminergic mechanism of antidepressant action in depressed patients, J. Affect. Disord., 86, 37, 10.1016/j.jad.2004.12.010 Winer, 2014, Development and validation of the Specific Loss of Interest and Pleasure Scale (SLIPS), J. Affect. Disord., 152–154, 193, 10.1016/j.jad.2013.09.010