Proximate and evolutionary studies of anxiety, stress and depression: synergy at the interface (original) (raw)

Neuroscience and biobehavioral reviews

Brain Research Bulletin, 1979

While enormous progress has been made in unraveling the proximate physiological mechanisms that account for anxiety, stress, and low mood, these states continue to give rise to considerable conceptual confusion. This is, in part, because proximate studies have neither been adequately distinguished from, nor integrated with, evolutionary explanations for the adaptive functions of anxiety, stress, and mood. A complete biological explanation that incorporates both proximate and evolutionary explanations will be of great value to better define the border between normal and pathological, to help to explain why pathological anxiety and depression are so common, and to provide a muchneeded basis for sensible decisions about when different pharmacological manipulations are likely to be helpful or harmful. Ideally, evolutionary considerations should provide a conceptual framework within which the biological significance of the proximate mechanisms can be better understood, and the proximate findings should provide tests of evolutionary hypotheses. Studies at the interface between evolutionary and proximate explanations will be difficult, but important to better understand individual differences in vulnerability and the etiology of diseases that result from dysregulation of anxiety and mood.

Anxiety Disorders in Evolutionary Perspective

Evolutionary Psychiatry, 2022

Anxiety disorders make sense only in the evolutionary context of the origins and functions of normal anxiety. Anxiety is an adaptation that adjusts diverse aspects of individuals in ways that increase fitness in dangerous situations. Subtypes were partially differentiated by different dangers. Anxiety is not fully differentiated from other aversive emotions, especially low mood. Anxiety disorders result when regulation systems fail. Explaining them requires considering five possible reasons for vulnerability. However, much harmful anxiety arises from normal mechanisms. These insights are valuable in the clinic, and they suggest new research initiatives.

Anxiety and Depression Disorders - Evolutionary Aspect (Wall Street International Magazine)

Anxiety and Depression Disorders - Evolutionary Aspect, 2019

Anxiety disorders are among the most common mental illnesses. Current treatments worldwide are not standardized nor effective as we would wish for, suggesting deeper understanding of the causes of anxiety. To understand anxiety disorders, it is necessary to understand the normal anxiety response. Very basic approach in understanding anxiety is to determine its causes and normal responses. Evolutionary theory predicts that the threshold for mounting an anxiety response should depend on the probability of dangerous events occurring in the current environment, and the vulnerability of the person to those events as critical criteria. The evolutionary criteria for when a mechanism is functioning adaptively are different from the criteria for identifying when a psychiatric disorder is present. Treatments for anxiety and depression at present, have limited efficacy. For example, for anxiety-depressive disorders, usage of antidepressants treat successfully every 6th patient. It means 6 patients need to be treated with the

The evolutionary origins of mood and its disorders

2012

The term 'mood' in its scientific usage refers to relatively enduring affective states that arise when negative or positive experience in one context or time period alters the individual's threshold for responding to potentially negative or positive events in subsequent contexts or time periods. The capacity for mood appears to be phylogenetically widespread and the mechanisms underlying it are highly conserved in diverse animals, suggesting it has an important adaptive function. In this review, we discuss how moods can be classified across species, and what the selective advantages of the capacity for mood are. Core moods can be localised within a two-dimensional continuous space, where one axis represents sensitivity to punishment or threat, and the other, sensitivity to reward. Depressed mood and anxious mood represent two different quadrants of this space. The adaptive function of mood is to integrate information about the recent state of the environment and current physical condition of the organism to fine-tune its decisions about the allocation of behavioural effort. Many empirical observations from both humans and non-human animals are consistent with this model. We discuss the implications of this adaptive approach to mood systems for mood disorders in humans.

Darwinian models of depression: A review of evolutionary accounts of mood and mood disorders

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2006

Over the last ten years, there has been increased interest in the evolutionary origins of depressive phenomena. The current article provides a review of the major schools of thought that have emerged in this area. First, we consider important Darwinian explanations of depressed mood, including an integrative social risk hypothesis recently proposed by the authors. According to the social risk hypothesis, depression represents an adaptive response to the perceived threat of exclusion from important social relationships that, over the course of evolution, have been critical to maintaining an individual's fitness prospects. We argue, moreover, that in the ancestral environment, depression minimized the likelihood of exclusion by inducing: (i) cognitive hypersensitivity to indicators of social risk/threat; (ii) signaling behaviours that reduce social threat and elicit social support; and (iii) a generalized reduction in an individual's propensity to engage in risky, appetitive behaviours. Neurobiological support for this argument is also provided. Finally, we review three models that endeavour to explain the relationship between the adaptations that underlie depressed mood and clinically significant, depressed states, followed by a consideration of the merits of each.

Evolutionary Approaches to Depression: Prospects and Limitations

Lay Summary : Evolutionary psychiatry has emerged to the status of an important theoretical perspective over the last two decades, and it has generated a sizeable volume of theoretical and empirical studies. It is understandable that many are attracted to the application of evolutionary principles to psychiatric phenomena. Some are attracted by the possibility of providing ultimate explanations for certain mental disorders, while others also think that such an approach can help to counterbalance a naïve understanding of mental disorder. As Nesse and Jackson [1: 194] put it, " campaigns to convince the public and practitioners that depression and anxiety are brain diseases have motivated much useful research and have decreased stigma, but they are biologically naive. An evolutionary approach supports a more medical model in which clinicians recognize many symptoms as defenses shaped by natural selection that are aroused by more primary causes, and others arising from defects in the systems that regulate defenses ". Nonetheless, while evolutionary psychiatry is assuming an increasing presence within psychiatric science, the " adaptive turn " has also generated a range of criticisms. Many researchers appreciate the contributions that evolutionary explanations offer for a number of mental disorders , but highlight serious problems that different versions of evolutionary explanations face. The investigation in this chapter was limited to addressing two evolutionary approaches to depression, the mismatch explanation and the persistence explanation. Although both accounts exhibit deficiencies, the conclusion that we should reject applications of evolutionary theory to depression is not warranted. Evolutionary psychiatry should be considered as a potential source of knowledge, and its heuristic value in the development of testable assumptions should not be ignored.

A neuro-evolutionary approach to the anxiety disorders* 1

Journal of anxiety disorders, 1997

Background: Advances in our understanding of the anxiety disorders and in the application of evolutionary principles to medicine provide the possible basis for a neuro-evolutionary approach to these conditions.

Anxiety Disorders as Evolutionary Adaptations

Religion, spirituality and health: a social scientific approach, 2017

The chapter examines the thesis, first advanced by clinical psychologists and psychiatrists in the 1970s and 1980s, that psychiatric symptoms are rooted in our evolution history. This premise has come to be called Evolutionary Psychiatry. Key among the early advocates of evolutionary psychiatry was the American psychiatrist Randolph M. Nesse who believed that many psychiatric disorders, particularly anxiety disorders, are expressions of proximate mechanisms that are adaptive for survival. This chapter explains how seven anxiety disorders reflect fears that evolved to protect us from different sources of dangers: acrophobia, agoraphobia, small animal phobias, general anxiety, society phobia (anxiety), panic attack, and obsessive compulsive disorder. The prevalence rates and age of onset of subclinical levels of these classes of psychiatric symptoms in the general public are presented wherever possible, and estimates are given regarding when some of the proximate mechanisms underlying these symptoms probably evolved in our animal or human ancestors. The chapter also explains that these proximate mechanisms are prone to making "false alarms," much as smoke alarms do, because they operate under the "better safe than sorry principle." A major point of the chapter is the same as the major premise of evolutionary psychiatry, i.e., that all people have subclinical levels of various psychiatric symptoms because the proximate mechanisms that produce them once were and may still be important for survival. The chapter also notes that the theoretical focus of evolutionary psychology on the last 1.8 million years of human existence is obviously inadequate for understanding how tens of millions and hundreds millions of years of evolution have molded human behavior.

Animal models of depression and anxiety: What do they tell us about human condition?

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2011

While modern neurobiology methods are necessary they are not sufficient to elucidate etiology and pathophysiology of affective disorders and develop new treatments. Achievement of these goals is contingent on applying cutting edge methods on appropriate disease models. In this review, the authors present four rodent models with good face-, construct-, and predictive-validity: the Flinders Sensitive rat line (FSL); the genetically "anxious" High Anxiety-like Behavior (HAB) line; the serotonin transporter knockout 5-HTT −/− rat and mouse lines; and the post-traumatic stress disorder (PTSD) model induced by exposure to predator scent, that they have employed to investigate the nature of depression and anxiety.