Personality traits such as extraversion, low self-esteem, and attraction to risk-taking behavior have generally been identified as psychological predictors of problem cell phone use.8 Even the American Psychiatric Association has picked up on this theme, featuring the topic of cellular phone addiction in adolescence at their 2006 annual meeting in Toronto.9
However, as with other addictions, this may not be the whole story. There may also be neurobiologic markers for addictions. Dopamine(Drug information on dopamine), the main neurotransmitter attributed to the reward system, has been singled out for this role and sets the stage for the concept of a "reward deficiency syndrome."6 In this schema, individuals possess a biologic vulnerability to addiction because of a malfunction in the dopamine system. Thus, anything that can stimulate or activate these reward centers can become "addictive." The object or substance that causes the stimulation in an individual brain may differ, but ultimately, it is the stimulation of neurobiologic circuitry in the CNS that underlies all addictions. It is this theory that has prompted the establishment of a treatment facility for video game addicts in Amsterdam. Gamers, the clinic directors assert, produce endorphins in response to continued game playing.10
Do electromagnetic fields from cell phones stimulate the brain?
We may indeed be addicted to technology, video games, computers, and the Internet, but in the case of cellular phones, it may be something more ominous than the mere act of using the phone that reinforces the behavior and makes the use addictive. Some clues may be emerging that cellular phone use has more direct effects on brain biology and chemistry. Annals of Neurology recently published a study by Ferreri and colleagues11 that demonstrated excitation of the motor cortex during exposure to the electromagnetic fields (EMFs) emitted by cellular phones. This report was quickly picked up by the major wire services and the results were widely reported on television, in newspapers, and on the Internet. Comparisons were quickly made between the excitation of the brain after using a cell phone and that experienced by the brain after having a cup of coffee.12 Might this be the key to explaining the link between cellular phones and addiction? Does the cellular phone actually stimulate the brain by the same or a similar mechanism as caffeine(Drug information on caffeine) does?
To discover the answer to that question, we must first consider how caffeine affects the brain. Caffeine stimulates the CNS by blocking the brain's neuroreceptors for adenosine(Drug information on adenosine), a neuro-modulator that produces sedation in several areas of the brain by blocking the release of excitatory neurotransmitters.13 Furthermore, caffeine is a noncompetitive inhibitor of adenosine deaminase (ADA).14 However, the CNS does not claim the largest concentration of this enzyme. Instead, it is highly concentrated in the lymph nodes, thymus, and spleen. It has an essential role in the functioning of both B and T lymphocytes, and a deficiency of ADA causes a severe combined immunodeficiency disease.15,16
Similarly, electromagnetic radiation from cellular telephones causes an oxidative stress that affects the levels of essential enzymes.17,18 At least one study has shown a decrease in the activity of ADA in embryonic fibroblasts exposed to EMFs.19 Low-frequency EMFs may cause an up-regulation of adenosine receptors and alter their responsiveness in human neutrophils.20 To further implicate the role that cellular phone emissions may have in causing chemical changes in animal cells, microwaves from cell phones can cause stress responses or DNA damage in human lymphocytes in some persons.21 Does the same thing happen in human brain tissue exposed to EMFs from cell phones?
We can only make inferences at this time, but it seems clear that cellular phones are here to stay. There can be no debate that cell phones produce EMFs. That these fields can affect human brain cells has also been shown. Addictive substances, such as caffeine, stimulate the brain; now we learn that cell phones do also, either by the same or a different mechanism. Is it just semantics that we may refer to the behavior of some persons who use these devices as an addiction, or is there really something more going on? While we debate, hundreds of millions of persons continue to expose themselves to these EMFs in what may yet become one of the largest uncontrolled experiments ever witnessed.22 If past experience is any indicator, cellular phone use may one day become a major public health issue in the same way cigarettes have been shown to be. The World Health Organization has been gathering data through the International EMF Project since 1996, but will not complete its risk assessments until 2007.23 Reports to date are equivocal: some series are demonstrating an increased risk of malignant brain tumors while others are not.22,24
Should you put down that cellular phone? Probably not (unless you're driving). However, should we continue to explore the effects of these devices on our lives, bodies, and minds? Most certainly.
Dr LaPorta is chair of the department of psychiatry at St. Joseph's Regional Medical Center in Paterson, NJ. She reports that she has no conflicts of interest with the subject matter of this article.