Low-dose environmental radiation, DNA damage, and cancer: The possible contribution of psychological factors

Abstract

Radiation causes DNA damage, increases risk of cancer, and is associated with psychological stress responses. This article proposes an evidence-based integrative model in which psychological factors could interact with radiation by either augmenting or moderating the adverse effects of radiation on DNA integrity and eventual tumorigenesis. Based on a review of the literature, we demonstrate the following: (1) the effects of low-dose radiation exposures on DNA integrity and on tumorigenesis; (2) the effects of low-dose radiation exposure on psychological distress; (3) the relationship between psychological factors and DNA damage; and (4) the possibility that psychological stress augments and that psychological resource variables moderate radiation-induced DNA damage and risk of cancer. The additional contribution of psychological processes to radiation-DNA damage-cancer relationships needs further study, and if verified, has clinical implications.

Effects on DNA Damage and/or Repair Processes as Biological Mechanisms Linking Psychological Stress to Cancer Risk

“…We further hypothesize that stress can result in suppression of DNA repair mechanisms, resulting in a “double whammy” of increased damage and decreased repair during times of stress. In support of this hypothesis are a considerable number of studies documenting the effects of psychological stress on DNA damage (reviewed by Cwikel, Gidron, & Quastel, ; Gidron, Russ, Tissarchondou, & Warner, ). For example, it has been reported in animal models that rotational stress impairs repair mechanisms for chemical carcinogen‐induced DNA damage (Glaser, Thorn, Tarr, Kiecolt‐Glaser, & D'Ambrosio, ) and psychological stress increases DNA damage as measured by levels of 8‐OHdG (a marker of oxidative DNA damage) (Adachi, Kawamura, & Takemoto, ).…”

“…The integrity of the human genome is continually threatened by exogenous (e.g., ultraviolet radiation from the sun) and endogenous (e.g., ROS produced as a by‐product of normal cellular metabolism) challenges that, if not kept in check by protective mechanisms (e.g., antioxidant activity, DNA repair), can result in increased damage to DNA and ultimately increased risk of cancer (Bernstein, Nfonsam, Prasad, & Bernstein, ; Cadet & Wagner, ; Hoeijmakers, ; Kryston et al., ; van Loon et al., ; Sedelnikova et al., ). A role for psychological stress as a contributor to increased DNA damage has been supported by correlational studies in humans (Cwikel et al., ; Gidron et al., ), as well as by experimental research with animals exposed to stress (Cwikel et al., ; Gidron et al., ) and cell lines exposed to stress hormones in vitro (Flint et al., , , ; Gidron et al., ; Hara et al., ). Critically lacking in the literature are experimental studies with humans to confirm a causal connection between psychological stress and increased DNA damage, despite the availability of well‐established methods (e.g., the Trier Social Stress Test) to reliably elicit stress responses in humans under controlled laboratory conditions, and in vitro evidence that exposure to stress hormones for as little as ten minutes can result in increased DNA damage (Flint et al., ).…”

“…At the systemic level, in vivo research is needed to investigate the role of stress‐induced neuroendocrine responses (e.g., increased circulating levels of catecholamines and cortisol) as instigators of stress‐induced increases in DNA damage. At the molecular level, research is needed to determine the contribution of stress effects on the two major pathways whose net activity largely determines ongoing levels of DNA damage (Kryston et al., ; Sedelnikova et al., ): (a) psychological stress may cause an increase in ROS levels (Cwikel et al., ; Gidron et al., ), resulting in increased oxidative DNA damage due to an imbalance in the usual dynamic equilibrium between ROS and antioxidant activity (a state described as “oxidative stress”; Dizdaroglu, ; Sedelnikova et al., ); and/or (b) stress may cause a reduction in DNA repair capacity (Cwikel et al., ; Gidron et al., ), resulting in an imbalance in the usual dynamic equilibrium between DNA damage and repair such that the cell would not be able to keep up with ongoing challenges to DNA integrity (Jalal, Earley, & Turchi, ; Kryston et al., ).…”

The Relationships between Cognitive Neuropsychological State, Oxidative Stress and Genotoxicity in Radiology Staff

“…Animals and humans have a lot of problems because of exposure to radiation such as: neuronal inflammation, apoptosis, reduced oligodendrocytes and myelin sheath, damage to neurons [29] [30], down-regulation of neural pathways in mice [31], cognitive disorders caused by micro environmental factors including oxidative stress and inflammation [32], psychological stress [33] and emotional stress [34]. In some patients who cured with radio therapy, memory deficits [35], depression [36].…”

Risk factors of depression after prolonged low-dose rate environmental radiation exposure

“…Moreover, following the Chernobyl disaster, the primary risk factor amongst the general population was perceived rather than actual exposure to harmful levels of radiation (Bromet 2012). Cwikel et al (2010) suggested that low-dose radiation exposure induces psychological stress responses because of awareness regarding the uncertainty of radiation risk (i.e., fear responses) and that psychological sequelae could affect the behavioural function of the central nervous system. In addition, depression is a well-known independent predictor of inferior HRQoL amongst patients with chronic diseases (Chung et al 2009, Cruz et al 2010.…”