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Confusing claims over internet addiction

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People addicted to the internet may experience “changes in the brain similar to alcoholics and cocaine addicts”, The Daily Telegraph has reported.

The claim is based on a study that compared the brain structure of teenagers with internet addiction disorder (IAD) with non-addicted peers. Although not universally recognised as a medical condition, IAD is considered to involve an inability to control internet use that causes social or behavioural problems or interferes with a person’s ability to function at school or work. The current study examined whether or not people with IAD exhibited differences in brain structure and volume compared with those without an internet addiction. Researchers found that those with IAD had significantly reduced density in several regions of the brain, and that this corresponded with poorer performance in tests of emotional disorders and addiction.

While this small study has found patterns in brain volume among people with IAD, it is not appropriate to assume that internet addiction causes changes to the brain, particularly as we cannot tell how their brains were structured before they began using the internet. Also, the study featured just 36 participants, meaning its results should be treated with caution.

Importantly, the changes described in this study were to the brains of adolescents with a specific, if new, disorder, and the brains of people who simply use the internet on a day-to-day basis were not assessed.

Where did the story come from?

The study was carried out by researchers from the Chinese Academy of Sciences and other institutions throughout China. It was funded by the Natural Science Foundation of China and the Chinese Academy of Sciences.

The study was published in the peer-reviewed journal PLoS ONE.

Several news headlines have suggested that internet addiction can cause changes to the brain, but this description is inappropriate, as the study design did not look at changes over time. It looked at how the brains of problem internet users differed from those of people who did not report such a problem. Therefore, it is entirely possible that the heavy users had particular brain structures that made them susceptible to addictions, rather than that the internet actively changed their brain structures. Assuming that the associations found by this research are confirmed in larger studies, it would take careful examinations over time to tell whether internet addiction causes changes in the brain, or if underlying differences in those structures contribute to addictive behaviours.

Also, some news sources have described internet addiction in a way that suggests it is an established medical condition, when it is not clearly defined or even universally recognised. For example, it was decided not to include it in the current Diagnostic and Statistical Manual of Mental Disorders (DSM-V), which is considered to be the bible of psychological disorders. Given the lack of a clear definition, The Independent’s claim that 5-10% of the UK population have internet addiction seems a little shaky. This would equate to millions of people, and it is not clear what this extremely high estimate is based on.

What kind of research was this?

This was a cross-sectional study that compared the density of particular brain structures in patients considered to have IAD and similarly aged peers.

As this was a cross-sectional study that assessed internet addiction and brain structure at only a single point in time, it cannot be used to determine causation, that is, whether use of the internet had some active influence over people’s brain structures. To determine causation would require further studies assessing brain structures before and after the onset of any addiction. However, there are several factors that make such an investigation unfeasible.

What did the research involve?

Researchers recruited 18 adolescents who had been diagnosed with internet addiction disorder by the psychiatry department of the Shanghai Mental Health Centre. The researchers also recruited a control group of 18 adolescents without IAD, matched with IAD participants in terms of age, gender and education. Participants were excluded from the study if they had a history of substance abuse or dependence, or any major psychiatric disorders.

A diagnosis of IAD was determined using an eight-item questionnaire. If participants responded ‘yes’ to the first five items, as well as at least one of the remaining three items, they were considered to have IAD. The questionnaire included the following questions:

  • Do you feel preoccupied with the internet (that is, think about previous online activity or anticipate your next online session)?
  • Do you feel the need to use the internet for increasing amounts of time in order to achieve satisfaction?
  • Have you repeatedly made unsuccessful efforts to control, cut back or stop internet use?
  • Do you feel restless, moody, depressed or irritable when attempting to cut down or stop internet use?
  • Do you stay online longer than originally intended?
  • Have you jeopardised or risked the loss of a significant relationship, job, educational or career opportunity because of the internet?
  • Have you lied to family members, a therapist or others to conceal the extent of involvement with the internet?
  • Do you use the internet as a way of escaping from problems or of relieving a distressed mood (for example, feelings of helplessness, guilt, anxiety and depression)?

All participants received a brain scan, which assessed white matter density and structure. White matter contains the brain cell fibres that transfer signals between different parts of the brain. The researchers compared the density of various white matter structures between the adolescents with IAD and those without IAD. The researchers did not define the specific structures they were interested in before conducting the study, but rather assessed a broad range of structures to determine if any were different between the two groups. Making multiple comparisons can increase the chances of finding a significant difference due to chance. The researchers corrected for this statistically.

Additionally, the 36 subjects completed questionnaires designed to assess various behavioural features, such as addiction, social relationships, time management, anxiety and emotional disorders, impulsiveness and family functioning. The researchers assessed differences in performance on the behavioural questionnaires between the IAD and non-IAD groups. They also compared brain regions that were perceived to be different between the two groups with these behavioural measures, in an effort to assess whether or not variations in brain structure were associated with differences in behaviour. In this analysis they corrected for multiple possible confounders, including age, gender, education and other psychological factors.

What were the basic results?

The scans of three participants (two controls and one with IAD) were unusable, and the three participants were excluded from the subsequent analysis.

The researchers found that those participants with IAD demonstrated a poorer performance in certain assessments of behavioural measures, including:

  • Young’s Internet Addiction Scale
  • the Strengths and Difficulties Questionnaire (which assesses emotional conduct and relationship problems)
  • the Screen for Child Anxiety Related Emotional Disorders

Compared with the control group, the IAD group had significantly reduced white matter density in 22 brain regions.

When examining the associations between behavioural measures and white matter density in the 22 identified structures, the researchers found:

  • higher (worse) score on the Screen for Child Anxiety Related Emotional Disorders was associated with lower density in the left side of the bundle of brain cell fibres that connect the two sides of the brain (p=0.008)
  • higher (worse) score on the Young’s Internet Addiction Scale was associated with lower density in another bundle of fibres called the ‘external capsule’ on the left side of the brain (p=0.018)

How did the researchers interpret the results?

The researchers say that “the results demonstrate that IAD is characterised by impairment of white matter fibres connecting brain regions involved in emotional generation and processing, executive attention, decision making and cognitive control”.


This was a small study that examined the association between brain structure and the diagnosis of internet addiction disorder. The results of the study should be interpreted cautiously, as the small number of participants increases the likelihood that the findings were due to chance. Additionally, the study cannot tell us anything about whether obsessive internet use causes changes to the brain, as some headlines have suggested. From this study we cannot rule out the possibility that the participants’ brains were structured this way before their heavy internet usage. If this were the case it would raise the possibility that their brain structure was responsible for their actions rather than their actions altering their brain structure.

Of course, there is also the question of whether the participants’ behaviour actually constitutes a medical condition. Internet addiction disorder is not included in the current Diagnostic and Statistical Manual of Mental Disorders, which outlines criteria for classifying and diagnosing mental disorders. That said, there is considerable debate surrounding whether or not to include it in the next edition of the manual. This means that this study could be improved if it were repeated once the definition and diagnostic criteria of IAD were to become established.

The researchers say that the identified brain regions are involved in emotional processing and addiction features, such as craving, compulsivity and maladaptive decision making. They also say that previous research has shown that abnormal white matter integrity in these regions is seen in people exposed to addictive substances such as alcohol, cocaine, heroin, marijuana and methamphetamines. However, this study did not assess a group of people who had other forms of addiction and it is not possible to say whether the white matter differences seen in the adolescents actually correlated with the pattern seen in people with other addictions.

Further limitations of the study include its reliance on self-report questionnaires for the diagnosis of IAD, and potential confounding by existing substance abuse or psychiatric disorders. The researchers say that while they attempted to control for these factors, such attempts may not have detected all cases.

This study has shown white matter differences in a small group of adolescents who reported internet addiction compared with those who did not. The causes of these differences were not determined in this study and a link to the brain changes seen in other addictions has not yet been established.

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