Journal of Cognitive Enhancement

, Volume 2, Issue 4, pp 364–368 | Cite as

Cognitive Enhancement with Brain Implants: the Burden of Abnormality

  • F. Gilbert
  • P. Tubig
Original Article


Reported clinical cases of patients with neurological disorders who have received brain implants which produced some degrees of cognitive enhancement introduce the possibility of using implantable neurotechnologies in healthy individual brains. However, little is known about the phenomenology of using implants for cognitive gains. Even if brain implants could augment one’s cognitive capacities, it would not guarantee a net benefit for the implanted individual. In this article, we examine the potential psychiatric effects of increased cognitive capacities, namely the burden of abnormality. We draw on a parallel phenomenon, known as the burden of normality, from clinical studies when patients who became suddenly symptom free after treatment with deep brain stimulation experienced psychiatric adverse effects. While we agree that cognitive enhancement could generate important postoperative benefits, we argue that patients augmenting their capacities will likely experience abnormality as much as, or perhaps even more so than normality.


Brain implant Burden of abnormality Burden of normality Cognitive capacities Cognitive enhancement Deep brain stimulation Parkinson’s disease Psychiatric adverse effects 

Cognitive enhancement refers to interventions to amplify or extend a person’s cognitive functions, such as long-term memory or intelligence, beyond the threshold of species typicality or “normality.” The idea of enhancing the cognitive capacities of healthy individuals has raised numerous concerns (Erler 2011; Garasic and Lavazza 2016; Lavazza 2017), but also has appealing reasons. For instance, Savulescu et al. (2011) argue that enhancing human cognition would likely increase human well-being. Similarly, Juth (2011) thinks that cognitive enhancement can promote autonomy. Many technologies that were initially developed to relieve cognitive and mood disorders are described as possible means to improve normal human capacities. These include pharmaceutical treatments such as methylphenidate (Colzato and Arntz 2017), non-invasive brain treatment such as transcranial magnetic stimulation (Ghanavati et al. 2018; Lavazza and Garasic 2017) and invasive brain treatment (Colzato et al. 2018). In this manuscript, we focus on invasive brain technologies, particularly deep brain stimulation (DBS).

In terms of enhancements, Hamani et al. (2008) and Adrian et al. (2010) have reported serendipitous correlations between DBS and cognition (e.g., memory), while Berney et al. (2002) and Houeto et al. (2002) have observed positive mood modification (e.g., decrease in major depressive tendencies). In addition, Tsai et al. (2010) and Haq et al. (2010) reported functional enhancements (i.e., increased libido). These discoveries have sparked great interest and speculation, especially with regard to future brain device implementations. However, little is known about the phenomenology of receiving implants for cognitive gains. Even if brain implants could augment one’s cognitive capacities, it would not guarantee a net benefit for the implanted individual. Relatively, little attention has been paid to the idea that patients treated successfully for their impairments might experience difficulties in adjusting to a normal or pre-impaired state. In a similar fashion, little is known about how enhanced individuals will cope with their subjective experience of being cognitively enhanced above normality or species-typical functioning, which suggests a level of abnormality.

Achieving successful medical outcomes does not necessarily warrant automatic benefit for treated individuals. This reality may be even more manifested with invasive brain surgery. Clinical studies of patients who have successfully undergone neurointervention have identified a range of side effects and complications in a number of domains: psychological, behavioral, affective, and social (Wilson et al. 2001; Wilson et al. 2007). In many cases, patients express difficulty adjusting from being chronically ill to their new status of being cured or asymptomatic. This postoperative response adjustment has been described as the burden of normality (BoN) syndrome (Wilson et al. 2001; Wilson et al. 2007; Gilbert 2012). A clinical association between the BoN and DBS for Parkinson’s disease (PD) has been previously discussed and detailed (Gilbert 2012; Weber et al. 2017; Bosanac et al. 2018). Available publications have reported cases of successfully treated PD DBS patients having clear motor improvement but experiencing feelings of estrangement with their new capacities (Schupbach et al. 2006). In Table 1, we demonstrate how some of our findings from DBS PD patients translate into BoN syndrome. Indeed, the type of changes defined in Table 1 is not strictly a side effect of the DBS or anterior temporal lobectomy (ATL), but rather a response to effective treatment. The BoN syndrome seems to originate in postoperative response improvements of neurological disorders rather than the type of brain surgery treatment. Our opinion is that these clinical observations may be reasonably analogized to the domain of cognitive enhancement using brain implants.
Table 1

Features of BoN in the postoperative adjustment process in patients with epilepsy treated with ATL compared to Parkinson’s disease treated with DBS. The left column provides the categorical referents (type of changes) as identified by Wilson et al. 2007. The middle column describes the features of the BoN as reported in the seminal paper by Wilson et al. 2001. The right column provides illustrative quotes for the parallel phenomena from work reported in Gilbert 2018 and Gilbert et al. 2017a

Type of changes

Features of BoN following ATL

(based on Wilson et al. 2001, 2007)

Parkinson’s patients treated with DBS

(from Gilbert 2018 and Gilbert et al. 2017a)


Changes in self-concept; patients perceive themselves differently.

“I feel like I am who I am now. But it’s not the me that went into the surgery […] No I cannot be the real me anymore - I cannot pretend.”

“I felt like I had lost my true self, it was way behind me.”


Changes in physical, vocational, social activities.

“I lost all interest in painting. […] I tried sitting down and painting something, but I just did not want to do it”.

“So from the sexual activity point of view, yes, I am enjoying a modicum of a very enjoyable sex life that I have never had a chance at before. I am not rushing around rubbing against every tree in the park or anything like that [laughs]…but it’s nice…67 years old thinking under normal circumstances thinking that was on the way out anyway”.


Changes in mood; fluctuations between euphoria and depression.

“There’s nothing that I can do because one of the electrodes is definitely very close to part of the brain that generates emotions… [..] If I had a choice I would say, ‘Look see what you can do…to stop me from doing that […] my emotional incontinence as I call it. Because it does get embarrassing. But if it meant going back to where I was pre-operation then I am going to put up with it.”


Changes in socio-familial dynamics and expectations such as separation and divorce.

“I think I have been causing a bit of problems in my relationships by being just so full on. […] “It’s a realization I have to slow down that activity and make it more manageable for myself and my wife.”

Patient: “My family say [sic] they grieve for the old [me]” […]

Interviewer: And what have your children said to you about the difference that they have seen before and after?

Patient: Yes, they said they do not recognize me.

Interviewer: And in what way do not they recognize you?

Patient: That I am so impulsive and seem to change my mind all the time.”

It is not only the narrative change from chronically ill to symptom free that encourages the BoN phenomenon to occur; otherwise, narratives related to intervention such as knee or hip surgery would lead to observation of the BoN syndrome in a high percentage of patients. In general, the BoN syndrome seems to be statistically observable with postoperative intervention related to brain surgery (Gilbert 2012). One way to understand the statistical correlation between brain surgery for neurological disorders and the phenomenon of BoN is to understand that direct interventions in the brain increase the probability of affecting neuronal regions associated with personality and self; hence, the risk of self-estrangement. By contrast, surgery to motor articulation parts of the body, for example, does not engender questions about the sense of self. These findings demonstrate that postoperative changes need not always affect narrative identity, but there are certain interventions that do disrupt it more significantly than others. Accordingly, we argue that cognitively enhanced individuals may face the risk of suffering and experiences similar to BoN, despite successfully matching outcomes that the intervention intended to produce.

Cognitive enhancement of healthy individuals amplifies certain cognitive abilities beyond statistically normal levels. In this sense, cognitively enhanced individuals become abnormal, an atypical embodiment that could shape profoundly their interactions with the world, its people and their sense of self. How might cognitively enhanced individuals experience their new cognitive aptitudes? Like the transition costs in becoming normal or symptom free from a status of sickness, we suggest the possibility of the cognitively enhanced individual experiencing substantial transition costs in becoming enhanced yet abnormal from the status of normality. Mirroring BoN, we call this the burden of abnormality (BoA). We know from individuals implanted with DBS that postoperative feelings of maladaptation appear largely to be correlated with a sense of radical inability to re-identify with their previous self, which reflects a drastic shift in their experience of the self (Gilbert 2013a, 2015a, 2018). This is what characterizes the burden of becoming normal. But, it is reasonable to infer that this burden would likely occur in the process of becoming cognitively enhanced. Like the former, cognitive enhancement involves introducing a novel form of embodiment, which would expectedly produce a dramatic shift in one’s experience of the self and subsequent feelings of distress and otherness. We argue that the direct alteration of a person’s cognitive capacities may lead to the kinds of burdens described in Table 1.

Table 1 provides a compelling account of how people experience BoN, such as how drastic change in the ability of the brain affects their conscious experience of themselves and the world around them. As a result, it also affects a person’s identity and social relationships. Thus, it is understandable for people to experience a drastic reformation in identity, social relationships, and pressures of new expectations attached to their newfound ontological status after undergoing a DBS intervention.

For instance, in Table 1, statements such as: “I felt like I had lost my true self” or “I can’t be the real me anymore - I can’t pretend” indicate how drastic changes may be experienced with respect to the postoperative sense of the self. In other terms, such excerpts illustrate how patients feel distinct from their prior self. The postoperative feelings that some patients appear to describe as a je ne sais quoi introduce the hypothesis that they might experience a profound sense of otherness or alterity rather than a difficulty to adapt to their previous normality. For instance, “There’s nothing that I can do because one of the electrodes is definitely very close to part of the brain that generates emotions… [..] If I had a choice I would say, ‘Look see what you can do…to stop me from doing that […] my emotional incontinence as I call it. Because it does get embarrassing” (Table 1). This example evokes the idea that patients experience a sense of loss of control and feelings of powerlessness vis-à-vis drastic and newly experienced emotions. BoN, we claim, arises not necessarily from the DBS itself, but from the affective changes brought about by the brain treatment. The manifestation of novel emotional phenomena can reasonably generate a worrying level of depersonalization.

From Table 1, we can see that in some cases, new drastic capacities appear to have been acquired for the first time after stimulation, suggesting that they did not necessarily exist prior to implantation (e.g., emotional responses, sexual drive). If these self-reports reveal emotions or capacities strictly coming into existence postimplantation, then it may suggest that cognitive enhancement would involve an unsettling experience of being abnormal, that is, the subject of new or newly heightened levels of existing capacities. Put otherwise, experiencing a normal cognitive capacity differently is not the same as experiencing an abnormal cognitive capacity. These observations seem to indicate that postoperative cognitive enhancement may point toward substantial BoA.

The prospect of experiencing BoA after undergoing cognitive enhancement does not necessarily mean that cognitive enhancement technologies should not be pursued. Rather, we want to challenge the presumption that heightening cognitive capabilities invariably enhances individual well-being. The possibility of BoA is an important consideration that should be included in the discourse of the ethics of cognitive enhancement. But, it is a consideration that requires greater empirical investigation. The seriousness of BoA depends on the nature and frequency of the phenomenon. For example, is BoA long lasting or temporary? Can certain interventions, like counseling, lessen the postoperative burdens? Will BoA be a common phenomenon among newly cognitively enhanced individuals? These details will significantly affect our moral evaluation of cognitive enhancement. More research is still needed to address these questions. For now, the documented findings of BoN in PD DBS users give us reason to question the psychiatric effects of cognitive enhancement as only improving individual well-being. Instead, we should hold a more complicated view of cognitive enhancement that seriously considers the possibility of BoA.


From our understanding, burden of abnormality (BoA) is analogous to BoN. BoN is the set of difficulties that a person encounters or experiences after undergoing efficacious psychosurgery for some disorder and attaining the status of normality. Similarly, BoA is the set of difficulties that a person would likely encounter or experience after undergoing efficacious psychosurgery for enhancing some normal, species-typical cognitive function, and attaining the status of abnormality.

The putative effects of cognitive enhancement on patient self and identity using deep brain stimulation (DBS) in particular remain an open source of debate in the scientific and neuroethical literature. Serendipitous and incidental effects observed in clinical settings should not automatically lead to conclusions supporting clinical trials (Viaña et al. 2017a, 2017b). Further research is required to unpack these putative cognitive effects, especially how cognitive enhancement affects how agents exercise control (Gilbert 2015b; Gilbert et al. 2017b). This research is crucial, as postoperative feelings of powerlessness and loss of control have been associated with increased risk of severe harm, including suicide attempts (Gilbert 2013a, 2013b), which can only be mitigated with better understanding through new discovery. The BoN and BoA teach us that successful medical outcomes do not warrant automatic net benefit and well-being for treated individuals.



We are grateful to the Journal of Cognitive Enhancement anonymous reviewers and editors for their valuable comments.

Funding information

This work was supported by grants from the National Science Foundation (NSF Award #EEC-1028725) and the Australian Research Council (DECRA award Project Number DE150101390).

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

Ethical Approval

All procedures performed studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.


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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  1. 1.School of HumanitiesUniversity of TasmaniaHobartAustralia
  2. 2.Centre for NeurotechnologyUniversity of WashingtonSeattleUSA
  3. 3.Department of PhilosophyUniversity of WashingtonSeattleUSA

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