Is internet addiction a valid psychiatric disorder?
Dr Sanju George
Consultant in addiction psychiatry
Birmingham and Solihull Mental Health NHS Trust
Dr Fionnbar Lenihan
Consultant in forensic psychiatry
Orchard Clinic Medium secure unit
Royal Edinburgh Hospital
The internet offers unlimited opportunities and benefits for most of its users but for a small minority its excessive use can have negative consequences. Young (1998) is credited with introducing the concept of ‘internet addiction disorder’ into the medical lexicon. A diagnosis still to receive official recognition in psychiatric classificatory systems such as ICD-10 (1992) and DSM-IV (1994), the concept of internet addiction is shrouded in conceptual and nosological ambiguity. Self-confessed evangelists proclaim internet addiction to be a distinct and valid psychiatric disorder (Young, 1998), whereas critics dismiss it as mere disease mongering (Lenihan, 2007). In this essay, we attempt to dispassionately scrutinise the evidence for (by Dr Sanju George) and against (by Dr Fionnbar Lenihan) the validity of the concept of internet addiction as a psychiatric disorder.
Internet addiction, although a concept still in its infancy (initially described only in 1996) is a term widely used in lay and medical literature. However, psychiatrists are yet to agree on whether it has successfully passed the test of conceptual validation as a psychiatric disorder. As an addiction psychiatrist, I have treated patients with internet addiction; so I know it exists. But is that sufficient evidence to state that it is a valid disorder? – NO. So the question I have attempted to answer is not ‘Does internet addiction exist?’ but ‘Is internet addiction a valid psychiatric disorder?’ – and this distinction is crucial. For a comprehensive response to whether internet addiction exists, please read the paper by Mark Griffiths (1998). Here, Mark Griffiths, a pioneer in internet addiction research, based on survey research of excessive internet use and case studies of internet addicts, argues that internet addiction is a bona fide addiction. Conceptual validation of internet addiction as a psychiatric disorder, however, is a much more difficult task. Psychiatric diagnostic validation varies depending on the validation criteria used. Robins and Guze (1970) were the first to propose formal criteria to establish the validity of a psychiatric diagnosis. Their five criteria were: clinical description, laboratory study, exclusion of other disorders, follow-up study and family study. Many modifications of these criteria have emerged since (Kendler, 1980; Kendell, 1989 and Andreasen, 1995) but Robins and Guze’s remains the gold standard. In this essay, I will apply Robins and Guze’s criteria to evaluate and establish or undermine the validity of internet addiction. Finally, at the outset it is also worth clarifying that the term validity is used in this section in the sense referred to by Kendler (1989) – i.e., “in the context of clinical psychiatry statements about diagnostic validity are essentially statements about predictive power, and hence their practical utility”.
Robins and Guze’s first criterion or phase – ‘clinical picture’ – was described as “either a single striking clinical feature or a cluster/group of features associated with one another.” They emphasized that the clinical picture includes not only symptoms, but also age at onset, sex, precipitating factors, etc. Describing the core clinical features of Phase I begins by describing single cases (case reports) and then proceeding to collect more information. Young (1998) was the first to describe a case of internet addiction – a young man who spent long hours on the internet, impacting negatively on his interpersonal and occupational life. Drawing on core symptoms clusters of pathological gambling, and addiction in general, she described the following core symptoms: preoccupation with the internet, tolerance, inability to cut back, spending more time online than intended, adverse consequences in interpersonal, educational or vocational spheres, lying to conceal the true extent of internet use and use of internet to escape problems. A slightly different core symptom group was proposed by Griffiths (1998) and consisted of salience, mood modification, tolerance, withdrawal symptoms, conflict and relapse. Later, Beard & Wolf (2001) refined the above symptom clusters and identified the following: preoccupation, tolerance, inability to cut back, restlessness when attempting to reduce use and spending more time online than intended. A major limitation of all the above is that they have not yet been thoroughly empirically tested. Factor analytic studies that explore whether these symptom clusters of internet addiction occur together are limited: only one such study was identified – Wang (2001) studied internet addiction among 217 University students in Australia and used factor analytic techniques (principal components extraction and oblimin rotation with Kaiser normalization) and extracted six factors as defining symptoms of internet addiction. These included uncontrollability, social escaping, social negativity, virtual identity, physical prolongation and virtual intimacy. Further going towards meeting the first of Robins and Guze’s criteria is epidemiological research that has shown the prevalence and core symptoms of internet addiction to be similar across populations and countries. Although the differing definitions used and other methodological limitations prevent determination of precise prevalence rates for internet addiction, the range quoted is from 2 to 6% of all online users. As internet is widely available only in developed countries, there have been no studies of internet addiction in the third world. Although most of the studies and research is from USA and UK, there have also been studies of internet addiction from Australia, Korea, Norway, etc. Studies of internet addicts have also looked at aspects of the clinical picture other than symptoms – i.e. age at onset, gender, etc. Shotton (1991), noted that addicted computer users were mainly male, highly educated and introverted. However, subsequent studies (Griffiths, 1997, 1998; O’Reilly, 1996; Young 1998) reported contrasting findings: dependent internet users were mostly middle-aged women on home computers.
The second Robins and Guze criterion – ‘laboratory studies’ – generally fall into two categories: biological markers (chemical, physiological, radiological findings, etc) and psychological tests (reliable and reproducible). Very little has changed since their original assertion in 1970 that – “unfortunately, consistent and reliable laboratory findings have not yet been demonstrated in the more common psychiatric disorders”. Or in other words, even today, there are no specific diagnostic laboratory tests for most psychiatric disorders. Conceptualising internet addiction as an addictive disorder, related to but distinct from pathological gambling, one could reasonably extrapolate findings from biological research in the field of pathological gambling. These studies have identified hemispheric dysregulation, dysfunctional neurotransmitter systems and physiological arousal (Raylu & Oei, 2002). Hence biological research into internet addiction should proceed along similar lines in future, if it is to receive credibility and diagnostic validity. Although no consistent psychological test finding has been noted in internet addiction, Armstrong et al (2000), using the MMPI-2 Addiction Potential Scale demonstrated that low scores of self-esteem (poor self-esteem) was a reliable predictor of internet addiction, whereas impulsivity was not. However, this finding has not been reliably replicated.
The third criterion in validating a psychiatric disorder – ‘delimitation from other disorders’ – states that it should be distinct and more than just another manifestation of some other illness with similar symptoms. Or in other words, this phase is about differentiating internet addiction from other disorders with similar symptoms. Applying this criterion to internet addiction is particularly difficult because internet addiction shares its core features with other addictive disorders. In fact, the diagnostic criteria for internet addiction were adapted from the DSM-IV criteria for substance dependence and pathological gambling. Most of the commonly used diagnostic criteria for internet addiction have been criticized for not specifying exclusion criteria. This limits the ability to exclude cases of internet addiction that could be a manifestation of other underlying psychiatric disorders, thereby compromising the homogeneity of the sample diagnosed as internet addicts. Critics also argue that some so-called ‘internet addicts’, for example those who gamble excessively online, are not really addicted to the internet but only use the internet “as a medium to fuel other addictions”. (Griffiths, 2000). Yet another complicating factor in differentiating internet addiction from other similar disorders is psychiatric comorbidity. The most common psychiatric disorders found to co-exist with internet addiction are affective disorders, other addictive disorders, impulse control disorder and personality disorders. Young and Rogers (1998), in a study of 259 internet addicts found a mean BDI score of 11.2 (SD = 13.9), and concluded that significant levels of depression were associated with internet addiction. Shapira et al ((2000) evaluated 20 internet addicts for psychiatric comorbidity and showed that all 20 had a lifetime DSM-IV Axis I disorder and 70% had a lifetime diagnosis of bipolar disorder. To fully satisfy criterion 3, further studies need to be done to establish whether internet addiction is distinguishable from other well-established chemical (drugs) and technological (e.g. gambling) addictions.
The last two criteria are perhaps the ones internet addiction is farthest from fulfilling. Criterion 4 – ‘follow-up study’ – is about demonstrating temporal stability of diagnosis. Follow- up studies of internet addicts will help determine whether it retains its distinct clinical symptom profile or whether over time it evolves into a different, established disorder. This is often ensured in psychiatric diagnostic systems by attaching a timeframe to diagnostic criteria, which is not the case for internet addiction. However, there are anecdotal case reports of internet addiction that remain relatively stable over time. To date, there have been no systematic follow-up studies of internet addicts and hence firm conclusions regarding the temporal stability of internet addiction cannot be drawn. However, such a lack of evidence regarding the temporal stability of internet addiction needs to be seen in the much wider context of psychiatric disorders in general. Garcia et al (2007) studied over 360,000 psychiatric diagnoses over time and concluded that “the diagnostic stability of mental disorders was poor” -this ranged from 29% to 70%. Criterion 5 – ‘family study’ – attempts to answer the questions – does a psychiatric disorder aggregate in families?” and whether there is a genetic basis to it? Research is virtually non-existent in this field for internet addiction. Family, twin and adoption studies, or even better still molecular genetic studies, similar to those carried out in other addictive disorders, will shed light on whether there is any genetic basis for internet addiction.
In summary, diagnostic validation in psychiatry is a complex process and especially so if using the Robins and Guze criteria, as this sets the bar very high; few psychiatric disorders fulfil all five criteria. From the above discussion it is reasonable to conclude that internet addiction achieves only partial diagnostic validity and that much more research is needed before internet addiction can stake a ‘valid’ claim for inclusion in ICD-10 or DSM-IV. However, that is not to say that internet addiction does not exist. Nor it is to say that the concept is not useful. However it is important to distinguish between the concept of validity and utility of psychiatric diagnosis (Kendell & Jablensky, 2003). Internet addiction, by such rigid syndrome validation criteria might fall short of qualifying as a valid psychiatric disorder yet, but I would argue that it continues to be a very useful concept. This high utility of the concept of internet addiction, as opposed to its as yet unestablished full validity, is a very useful working concept for professionals in the field as it conveys useful information on its characteristics, treatment response and outcome. Although I acknowledge that I have not answered all questions about internet addiction’s diagnostic validity adequately enough to be convincing about its existence as a distinct and valid entity, it is hoped that this essay will stimulate further debate on the diagnostic validity and encourage research into gaps in the evidence base of internet addiction.
The business of what is, and what is not, an addiction does not take place in a vacuum. From "reefer madness" (Gasnier, 1936) to the "War on Drugs" (Rand Corporation, 2005), the concept of addiction, the supposed non-volitional nature of some behaviours, has been used to justify the criminalization of drug users and dealers, the interdiction of supply routes and the destruction of drug crops.
In this response I propose to move from the general to the specific, to first examine the concept of behavioural addiction before moving to the problems, both conceptual and practical, I believe would be caused by an uncritical acceptance of Internet Addiction as a diagnostic entity.
Conceptual problems with behavioural addictions
The addiction concept has traditionally been associated with the pharmacological effects of various chemicals such as the development of tolerance and withdrawal states. Both of these are fairly "hard" measures unlike addiction symptoms such as drug-seeking behaviour, salience of drug, neglect of other interests and persistence despite harm, which are more contextual and socially constructed. This traditional model of addiction both validates and is validated by animal models where an animal is given the opportunity to self-administer opiates or other addictive drugs and does so to the exclusion of more evolutionarily adaptive behaviours such as mating and foraging. Leshner sums up this view by referring to drug addiction as "a chronic, relapsing disease that results from the prolonged effects of drugs on the brain." Note that the disease is attributed to the effects of the drug – it is in that sense like asbestosis or miner’s lung.
The relative nosological solidity of even these "traditional" addictions is itself not beyond challenge however. It has long been known (Evans, 1981) that only a minority of patients appropriately prescribed strong opiate painkillers go on to develop a full dependence syndrome despite the development of tolerance and withdrawal symptoms. In the 19th century heroin and other strong opiates were generally available with few restrictions but rates of dependence were apparently quite low (Weatherall, 1996). More recently, Alexander controversially claimed that it is the environmental impoverishment in which a laboratory animal typically lives that determines whether or not it will use a substance compulsively and to the exclusion of other activities. When he enriched the environment of his "rat park" with secluded nesting areas, play items, privacy and more natural food supplies, according to Alexander, the rats ceased to prefer opiate solution and selected water (Alexander et al, 1981).
Addiction became even more abstract when Griffiths introduced the concept of behavioural addiction (Griffiths, 1996). It has subsequently become widely, though not universally, accepted. However, some workers in the addictions field such as Orford have expressed reservations about the historic association of the word addiction with substances and have suggested that "excessive appetites" would be a more neutral term (Orford, 2001).
If, as we saw above, even chemical addictions are mediated by social and environmental contexts then it would seem likely that behavioural addictions are even more so.
Another problem is that, even if we concede the overall validity of behavioural addictions, how do we "carve nature at the joints" and isolate the specific addiction. For example is a compulsive Internet gambler a gambling addict or an Internet Addict or a computer addict?
The conceptual basis of behavioural addictions is also somewhat undermined by the sheer number of these conditions. As well as the familiar behavioural addictions to gambling, shopping, food and sex, suggested additions to the diagnostic manuals include addictions to tanning, videogames, chocolate, crime and brands (Kaur et al, 2006; Moran, 2007; Hetherington & MacDiarmid, 1993; Hodge et al, 1997; Boorman, 2007). There is an analogy here with the plethora of specific phobias once tediously enumerated in psychiatric textbooks but now thankfully herded together into ICD-10 F40.2.
On a more serious note, the creation of a host of diagnostic entities to explain (or at least label) maladaptive behaviours such as those we are considering has the potential to individualize problems and divert attention from relevant societal issues (Orford, 2001; Lee et al, 2004).
There is also a risk that the creation of these labels will divert attention from relevant psychiatric comorbidities of a more familiar kind. Orford (2005) points out the likely role of impulsivity as a personal characteristic in a variety of addictions suggesting links with personality. Studies have indeed shown that comorbidity of behavioural addictions with Axis I or Axis II disorders is the rule rather than the exception (Cunningham-Williams et al, 1998; Petry et al, 2005; Adamson et al, 2006; Kruedelbach et al, 2006).
Bickel and colleagues (Bickel & Marsch, 2001) link together the last 2 points, that of external context and personal comorbidity, in their paper applying the economic concept of "discounting" to various personality traits. A narrow focus on individual behavioural addictions may hinder rather than help this kind of interdisciplinary approach.
Habitual behaviours may have been adaptive in the environment of evolutionary adaptiveness (EEA) (Thornhill, 1997) and their neurobiological underpinnings are not in any sense a disease (Bouissac, 2006). While it is indisputable that these behaviours can have deleterious consequences - for some people in some contexts, we need to maintain a wider perspective, avoiding an exclusive focus on the object of "addiction" (be it drugs, food, gambling or the Internet).
Specific conceptual problems with Internet Addiction
It is perhaps worth stating at this point that the concept of Internet Addiction was originally proposed humorously. The joke of course lay in the proposal to create an online support group for sufferers (Suler, 2004).
Dr George cites statistical and neuroimaging research as being supportive of a valid concept of Internet Addiction. However, as Charlton (2002) pointed out, in the absence of a clear etiological model any attempt to apply DSM-IV criteria of addiction to computing-related activities is likely to overestimate the numbers affected. While statistical techniques such as cluster or factor analysis can inform us about the internal coherency of a diagnostic concept they cannot, on their own, establish the construct validity.
Neuroimaging differences between "Internet Addicts" and non-addicts similarly, do not, in themselves, necessarily establish the validity of the diagnosis, as there are also neuroimaging correlates for purchasing decisions, brand recognition and political affiliation (McClure et al, 2004; Knutson et al, 2007).
If we turn now to some of the proposed criteria for Internet Addiction then “excessive use” seems to be a relatively straightforward requirement, a straightforward translation from familiar substance dependence criteria. Complexities emerge however in the transition from compulsive use of chemicals to complex, socially embedded behaviours. For it to be a valid addiction, the excessive use must surely be a voluntary (or as voluntary as addictive behaviour can be) choice. A call-centre operator working at a computer for 16 hour a day will probably meet the excessive use criterion. Nevertheless he or she will not presumably be an addict. A programmer in a "start-up" company will similarly put in very long hours with a computer. He or (less probably) she will similarly not have much choice in this. However, in a more distal sense, as a result of career choice, he or she may have indirectly chosen this life.
Following on from the excessiveness criterion we come to the need for harm. The potential circularity problems stemming from this have been noted elsewhere (Lenihan, 2007). Explaining excessive, harmful Internet use by recourse to the term "addiction" is, in reality, not an explanation as much as a description.
The requirement for harm also leaves open the question as who defines the harm. In the absence of subjective distress this may be a matter of perspective. A verbally orientated, socially skilled, mental health professional may have a different concept of what constitutes a meaningful and worthwhile life than a young man with relative deficits in social skills and communication. Given the historical associations between addiction and coercion noted above this alone should give us pause for thought. I have elsewhere suggested that the economic idea of opportunity cost may be useful in thinking about these issues. What has the putative addict not done as the result of the behaviour? Would the activity or achievement have been highly valued for him? Would he have been able to take advantage of the lost opportunities?
Perhaps, for some people, the online world offers a richer life with better social prospects than the real world. There have, after all, always been loners and recluses and there has always been escapism. We may be in danger of repeating the mistakes of the "oralist" teachers of the deaf (Baynton, 1998) who, out of misguided kindness, sought to suppress signing culture. Those who spend little time online, or who only use the Internet for work and shopping, may not appreciate the diversity and scale of activities accessible via the Internet. It could be argued that immense social enterprises like the Linux operating system or the Second Life shared virtual reality are cultural creations which will some day be regarded as being on a par with the Cathedrals of medieval Europe or the Icelandic sagas.
The Practical Utility of Internet Addiction
The bringing into being of new diagnostic entities (often culture-bound entities) is itself a culture-bound phenomenon. In the United States a healthcare system dominated by private insurers acts as a powerful driver for the expansion and reification of diagnostic systems since "getting a diagnosis" may be the only way to get help (Caplan & Cosgrove, 2004; Walker, 2006).
A publicly funded system like the UK NHS should be less susceptible to these pressures though there may be other factors at work such as those described by Smith. It may be that, without imputing any sinister motives, people working in a field will naturally tend to see the expansion of that field as an unqualified good.
It is difficult for the profession to distance itself from accusations of "disease mongering" (Moynihan & Smith, 2002) when, as Double (2002) has pointed out, the number of recognised mental disorders has increased from 106 in 1952 (DSM-I) to 357 with the release of DSM-IV in 1994. With more disorders comes more disordered people; according to the International Labour Organisation (ILO) 16% of the adult population now suffer from a mental disorder.
Other authors have expressed concern about the increased use of psychotropic drugs, attributable, at least in part, to less stringent criteria for the diagnosis of depression (Parker, 2007). The apparent "epidemic" of autism in recent years, at least partly attributable to a relaxation of diagnostic criteria (Gernsbacher et al, 2005), has led to a reduced uptake of vaccination and current concerns about a resurgence of measles (Chen et al, 2004; Casiday et al, 2006).
Defining a behavior as a disease has yet more consequences. While we as a profession can maintain that our diagnostic entities do not necessarily have legal significance an adversarial legal system is not obliged to respect this, rather coy position. The Galbraith judgment broke new ground in Scots law by recognizing the diagnosis of "battered spouse syndrome" (DSM-IV) as grounds of diminished responsibility in a homicide case. While this may seem humane, the inevitable consequence of diminished individual responsibility is increased professional and institutional responsibility (and power). With the recent expansion of the legal category of mental disorder in England to include sexual deviancy yet more behaviours will be brought into the realm of psychiatric compulsion.
This is therefore the time to restrict, not to widen, concepts of mental disorder so as to ensure that an absurdly large proportion of the population are not removed from the workforce, stripped of moral autonomy or made subject to compulsory detention and treatment.
In an earlier article I wrote about the limitations of current concepts of "Internet Addiction" in the context of an increasingly pervasive Internet, which permits one to shop, work, play games and socialise online. These trends can only intensify with, for example, the development of "augmented reality" systems which overlay the virtual world on the real world (Azuma et al, 2001) and the Internet-enabling of everyday objects (Gershenfeld et al, 2004) to the point where Internet Addiction as a concept will seem as meaningless as "air addiction". There is, of course, a generational aspect to this and it is likely that psychiatrists in the not-so-distant future will regard the idea of Internet Addiction as an embarrassing anachronism like the masturbation panics of the 19th Century.
The absence of a specific diagnostic label does not mean we need necessarily withhold help from those who find their computer / Internet usage subjectively distressing and wish to reduce it. The "poorly defined and undertaught clinical skill" (Eells et al, 1998) of formulation is more suited to capturing the contextual and multifactorial nature of harmful computer use than any single code. If, for reasons of audit or finance, a precise diagnostic code is needed we could, following the example of the specific phobias, use ICD-10 F63.9 (Habit and impulse disorder, unspecified).
In summary, it is important to note that it is in the nature of articles such as this to generate dialectic, to sharply contrast differing views. In reality there are many areas of agreement between Dr George and I. Computer / Internet use, like all behaviours, has the potential to become compulsive. This may be part of the way the human motivational / reward system has evolved. Recognizing this, we should be willing to help those who come to us with this kind of problem while at the same time emphasizing the primacy of individual responsibility. Reifying these behaviours with individual labels opens up larger areas of life to societal control and coercion, reduces the scope of individual autonomy and mastery, wastes limited health care budgets, contributes to the medicalisation of society, and opens up our specialty to public ridicule. The pervasiveness of the Internet and the wide range of online activities, make it likely that a diagnostic entity of Internet Addiction will soon be perceived as increasingly anachronistic and its existence will do little to improve public health.
Adamson, S. J., Todd, F. C., Sellman, J. D., Huriwai, T., Porter, J., & Anonymous (2006). Coexisting psychiatric disorders in a New Zealand outpatient alcohol and other drug clinical population. Australian & New Zealand Journal of Psychiatry, 40(2), 164-70.
Andreasen, N. (1995) The validation of psychiatric diagnosis: New models and approaches. American Journal of Psychiatry, 152:2, 161-162.
Alexander, B. K., Beyerstein, B. L., Hadaway, P. F., & Coambs, R. B. (1981). Effect of early and later colony housing on oral ingestion of morphine in rats. Pharmacol Biochem Behav, 15(4), 571-6.
American Psychiatric Association (1994) Diagnostic and Statistical Manual of Mental Disorders (4th edn) (DSM-IV). APA.
Armstrong, L, Phillips, J.G, & Saling, L.L. (200) Potential determinants of heavier internet usage. International Journal of Human-Computer Studies, 53,537-550.
Azuma, R., Baillot, Y., Behringer, R., Feiner, S., Julier, S., & MacIntyre, B. (2001). Recent advances in augmented reality. Computer Graphics and Applications, IEEE, 21(6), 34-47.
Baynton, D. C. (1998). Forbidden Signs: American Culture and the Campaign against Sign Language. University Of Chicago Press.
Beard, K.W. & Wolf, E.M. (2001) Modification in the proposed diagnostic criteria for internet addiction. Cyber Psychology and Behaviour, 4, 377-383.
Bickel, W. K., & Marsch, L. A. (2001). Toward a behavioral economic understanding of drug dependence: delay discounting processes. Addiction, 96(1), 73-86.
Boorman (2007). Bonfire of the Brands: How I Learnt to Live without Labels. Canongate Books Ltd.
Bouissac, P. (2006). Hoarding behavior: A better evolutionary account of money psychology? Behavioral and Brain Sciences, 29(02), 181-2.
Caplan, P. J., & Cosgrove, L. (2004). Bias in Psychiatric Diagnosis. Jason Aronson.
Casiday, R., Cresswell, T., Wilson, D., & Panter-Brick, C. (2006). A survey of UK parental attitudes to the MMR vaccine and trust in medical authority. Vaccine, 24(2), 177-84.
Charlton, J. P. (2002). A factor-analytic investigation of computer 'addiction' and engagement. British Journal of Psychology, 93(Pt 3), 329-44.
CHEN, W., LANDAU, S., SHAM, P., & FOMBONNE, E. (2004). No evidence for links between autism, MMR and measles virus. Psychological Medicine, 34(03), 543-53.
Cunningham-Williams, R. M., Cottler, L. B., Compton, W. M., Spitznagel, E. L., & Anonymous (1998). Taking chances: problem gamblers and mental health disorders--results from the St. Louis Epidemiologic Catchment Area Study.erratum appears in Am J Public Health 1998 Sep;88(9):1407. Am J Public Health, 88(7), 1093-6.
Double, D. (2002). The limits of psychiatry. BMJ, 324(7342), 900-4.
Eells, T. D., Kendjelic, E. M., & Lucas, C. P. (1998). What's in a Case Formulation?: Development and Use of a Content Coding Manual. J Psychother Pract Res, 7(2), 144-53.
Enrique Baca-Garcia et al. (2007). Diagnostic stability of psychiatric disorders in clinical practice, British Institute of Psychiatry, 190:210-216.
Evans, P. J. D. (1981). Narcotic addiction in patients with chronic pain. Anaesthesia, 36(6), 597-602.
Gernsbacher, M. A., Dawson, M., & Goldsmith, H. H. (2005). Three Reasons Not to Believe in an Autism Epidemic. Current Directions in Psychological Science, 14(2), 55-8.
Gershenfeld, N., Krikorian, R., & Cohen, D. (2004). The Internet of Things. Scientific American, 291(4), 76-81.
Griffiths, M. D. (1996). Behavioural addiction: an issue for everybody. Journal of Workplace Learning, 8(3), 19-25.
Griffiths, M. (1997) Psychology of computer use: XLIII. Some comments on ‘Addictive use of the internet’. Psychological Reports, 80, 81-82.
Griffiths, M. (1998) Internet addiction: Does it really exist? In Psychology and the internet (ed. Jgackenbach), pp. 61-75. Academic Press.
Griffiths, M. (2000) Internet addiction – Time to be taken seriously? Addiction Research, 8, 413-418.
Hamann, S., Kilts, C., Harenski, K., & Westen, D. I. Blue Brain, Red Brain: Democrat and Republican fMRI Responses to Politicians' Faces.
Hetherington, M. M., & MacDiarmid, J. I. (1993). " Chocolate addiction": a preliminary study of its description and its relationship to problem eating. Appetite, 21(3), 233-46.
Hodge, J. E., McMurran, M., & Hollin, C. R. (1997). Addicted to Crime? Wiley.
Kaur, M., Liguori, A., Lang, W., Rapp, S. R., Fleischer, A. B., & Feldman, S. R. (2006). Induction of withdrawal-like symptoms in a small randomized, controlled trial of opioid blockade in frequent tanners. Journal of the American Academy of Dermatology, 54(4), 709-11.
Kendell, R.E. (1989). Clinical Validity. Psychological Medicine, 19:45-55.
Kendell, R. and Jablensky, A. (2003). Distinguishing between the validity and utility of psychiatric diagnoses, American Journal of Psychiatry, 160:4-12.
Kendler, K. (1980). The nosologic validity of paranoia (simple delusional disorder): A review. Archives of General Psychiatry, 37:699-706.
Knutson, B., Rick, S., Wimmer, G. E., Prelec, D., & Loewenstein, G. (2007). Neural Predictors of Purchases. Neuron, 53(1), 147-56.
Kruedelbach, N., Walker, H. I., Chapman, H. A., Haro, G., Mateu, C., et al. (2006). Comorbidity on disorders with loss of impulse-control: pathological gambling, addictions and personality disorders. Actas Esp Psiquiatr, 34(2), 76-82.
Lee, S., Mysyk, A., & Anonymous (2004). The medicalization of compulsive buying. Soc Sci Med, 58(9), 1709-18.
Lenihan, F. (2007). Computer addiction-a sceptical view: INVITED COMMENTARY ON: LOST ONLINE. Advances in Psychiatric Treatment, 13(1), 31.
McClure, S. M., Li, J., Tomlin, D., Cypert, K. S., Montague, L. M., & Montague, P. R. (2004). Neural Correlates of Behavioral Preference for Culturally Familiar Drinks. Neuron, 44(2), 379-87.
Moran, M. (2007). AMA Acts on Critical Psychiatry-Related Issues. Psychiatric News, 42(14), 5.
Moynihan, R., & Smith, R. (2002). Too much medicine. Br Med J, 324(7342)
O’Reilly, M. (1996) Internet addiction: A new disorder enters the medical lexicon. Canadian Medical Association Journal, 154, 1882-1883.
Orford, J. (2001). Addiction as excessive appetite. Addiction, 96(1), 15-31.
Parker, G. (2007). Is depression overdiagnosed? Yes. BMJ, 335, 328.
Petry, N. M., Stinson, F. S., Grant, B. F., & Anonymous (2005). Comorbidity of DSM-IV pathological gambling and other psychiatric disorders: results from the National Epidemiologic Survey on Alcohol and Related Conditions. J Clin Psychiatry, 66(5), 564-74.
Raylu, N. & Oei, T.P.S. (2002). Pathological gambling: A comprehensive review, Clinical Psychology Review, 22, 1009-1061.
Robins, E. and Guze, S.B. (1970). Establishment of psychiatric validity in psychiatric illness: its application to schizophrenia. American Journal of Psychiatry, 126:7: 983-987.
Shapira, N.A, Goldsmith, T.D, Keck, P.E, Khosla, U.M, McElroy, S.L. (2000) Psychiatric features of individuals with problematic internet use. Journal of Affective Disorders, 57, 267-272.
Shotton, M. (1991) The costs and benefits of computer addiction. Behaviour and Information Technology, 10, 219-230.
Smith, A. An Inquiry Into the Nature and Causes of the Wealth of Nations.
Suler (2004). Computer and cyberspace addiction. International Journal of Applied Psychoanalytic Studies, (1), 359-62.
Thornhill, R. (1997). The concept of an evolved adaptation. Ciba Found Symp, 208, 4-13.
Walker, M. T. (2006). The Social Construction of Mental Illness and its Implications for the Recovery Model. International Journal of Psychosocial Rehabilitation, 10(1), 71-87.
Wang, W. (2001) Internet dependency and psychosocial maturity among college students. International Journal of Computer Studies, 55, 919-938.
Weatherall (1996). Drug treatment and the Rise of Pharmacology. In Cambridge Illustrated History Of Medicine (pp. 258). Cambridge:
Young, K.S. (1998) Caught in the Net: How to recognise the signs of internet addiction and a winning strategy for recovery. John Wiley & Sons.
Young, K. & Rogers, R.C. (1998) The relationship between depression and internet addiction. CyberPsychology and Behaviour, 1, 25-28.
Copyright Priory Lodge Eduction 2008
First Published January 2008