A proposed mechanism for chemotherapy-related cognitive impairment (‘chemo-fog’)

Abstract

SUMMARY What is known and Objective Chemotherapeutic drugs for cancer treatment are, of necessity, cytotoxic. Unintended damage to normal central nervous system neuronal structure or function might lead to deleterious adverse effects on cognitive function, a mild form of which is reported by some cancer survivors. Understanding the physiologic connection between cancer chemotherapy and the reported cognitive dysfunction, could help inform choice of drugs, treatment regimens and new drug development. Our objective is to comment on a proposed mechanism for ‘chemo-fog’. Comment An increasing number of patients are surviving cancer and are generating a new and rapidly growing category within the healthcare system. Some of these cancer survivors are reporting that they are experiencing residual and lingering effects from the cancer, or from its treatment, and that they now need care as survivors. This has given rise to the new field of ‘survivor care’. Control of chemo-fog is an important aspect and understanding its mechanism, the basis for more rationale therapy. Such insight would also help direct drug-discovery efforts. What is new and Conclusion New evidence suggests that ‘chemo-fog’ may be due to excessive cytokine release by the cytotoxic agents. Control of the elevated levels of the blood–brain-barrier-permeable pro-inflammatory cytokines, may help minimize this adverse effect.

What is Neurofeedback: An Update

“…Preliminary reports have also been published on the use of neurofeedback with chronic fatigue syndrome (Hammond, 2001b); Tourette's (Tansey, 1986); obsessive-compulsive disorder (Hammond, 2003(Hammond, , 2004Surmeli, Ertem, Eralp, & Kos, 2011); Parkinson's tremors (M. Thompson & Thompson, 2002); tinnitus (Crocetti, Forti, & Bo, 2011;Dohrmann, Elbert, Schlee, & Weisz, 2007;Gosepath, Nafe, Ziegler, & Mann, 2001;Schenk, Lamm, Gundel, & Ladwig, 2005;Weiler, Brill, Tachiki, & Schneider, 2001); pain (Ibric & Dragomirescu, 2009;Jensen, Grierson, Tracy-Smith, Bacigalupi, & Othmer, 2007;Sime, 2004); physical balance, swallowing, gagging, and incontinence (Hammond, 2005a); children with histories of abuse and neglect (Huang-Storms et al, 2006) or reactive attachment disorder (Fisher, 2009);cerebral palsy (Ayers, 2004); restless legs and periodic limb movement disorder (Hammond, in press); physical and emotional symptoms associated with Type I diabetes mellitus (Monjezi & Lyle, 2006); essential tremor; and for ''chemo fog'' (Raffa & Tallarida, 2010;Schagen, Hamburger, Muller, Boogerd, & van Dam, 2001) following chemotherapy or radiation treatments.…”

Prevalence, mechanisms, and management of cancer-related cognitive impairment

“…It is well established that inflammation plays a role in cognitive dysfunction and “sickness behavior” (e.g. fatigue, sleep dysfunction, loss of appetite, withdrawal and other psychological symptoms: all symptoms experienced by cancer patients) (Dantzer & Kelley, 2007), and this has led several investigators to propose inflammation as central to CRCI etiology (Ahles & Saykin, 2007; Cleeland et al, 2003; Raffa, 2011). …”

Cytokines as Mediators of Chemotherapy-Associated Cognitive Changes: Current Evidence, Limitations and Directions for Future Research

“…Notably, recent experimental studies have suggested that pro-inflammatory cytokines may be mediators of chemotherapy-associated cognitive changes[10]–[17]. Cytokine induction in the central nervous system has been suggested to mediate "sickness behavior" in patients with severe infection or cancer, together with the adverse neuropsychiatric effects of treatment with interferon and interleukins[13].…”