<h3>Nehligh's 2010 review</h3>
<p>Nehlig (2010) wrote a systematic review article called &quot;Is caffeine a cognitive enhancer?&quot; (<a href="http://iospress.metapress.com/content/lw1630245745v088/" rel="nofollow noreferrer">link to publisher, no PDF</a>).
On page S89 to S90 Nehlig reviews the evidence of caffeine as a cognitive enhancer within the context of a history of caffeine consumption:</p>
<blockquote>
<p>In
caffeine non-deprived young (20–25 years) and older subjects (50–65
years), 250 mg caffeine slightly offset the decline in performance
found in the placebo group on a digit span memory test. However,
caffeine did not improve performance in the immediate word recall
task in either age group [11]. Caffeine (12.5–100 mg) given after
overnight abstinence improved cognitive performance in a relatively
difficult and stressful task involving rapid visual information
processing and using a high load of working memory in 11 males and 12
females, aged 18–56 years. The effect was more marked in individuals
with a high habitual caffeine intake [78]. In 68 volunteers
consuming a regular daily amount of caffeine, 2 mg/kg caffeine
improved the speed of encoding new information in a categorical search
task [79]. Likewise, in a study comparing 24 non-consumers (20
mg/day) to 24 consumers of caffeine (217 mg/day), there was no
baseline difference between group performances. Caffeine improved
numeric working memory reaction time and sentence verification
accuracy; alertness was also increased, but in general caffeine tended
to improve more the performance in non consumers [80].</p>
<p>In adult
subjects, a higher habitual caffeine intake with no additional
caffeine administration on the day of testing was positively related
to better performance on incidental verbal learning and visuospatial
learning tasks [15]. There was also an association between estimated
caffeine intake and performance in a choice reaction time task, and in
delayed recall of a verbal word learning task [81]. In the former
study, older sub- jects appeared to benefit more from higher caffeine
intake [15], while this was not the case in the latter study [81].
Also, in real life activities, regular caffeine consumption might
benefit cognitive functioning in a non-working population [82].</p>
</blockquote>
<h3>Smith's 2002 review</h3>
<p>Another good review is provided by Smith (2002, <a href="http://intraspec.ca/Effects-of-caffeine-on-human-health.pdf" rel="nofollow noreferrer">PDF</a>).
The main claim relevant to the present question argues that coffee remains beneficial despite habituation:</p>
<blockquote>
<p>It has been claimed that the positive eﬀects of caﬀeine really reﬂect
removal of negative eﬀects of caﬀeine withdrawal. This view cannot
account for eﬀects observed in non-consumers or nondeprived
individuals. In addition, there is little evidence of caﬀeine
withdrawal impairing tasks which show improvements following ingestion
of caﬀeine.</p>
</blockquote>
<p>The article is worth reading if you want to read about the relevant empirical evidence and some of the limitations of existing research.</p>
<h3>References:</h3>
<ul>
<li><sub>[11] Rees K, Allen D, Lader M (1999) The influences of age and
caffeine on psychomotor and cognitive function. Psychophar-
macology (Berl) 145, 181-188.</sub></li>
<li><sub>[78] Smit HJ, Rogers PJ (2000) Effects of low doses of caffeine
on cognitive performance, mood and thirst in low and higher
caffeine consumers. Psychopharmacology (Berl) 152, 167-
173.</sub></li>
<li><sub>[80] Haskell CF, Kennedy DO, Wesnes KA, Scholey AB (2005)
Cognitive and mood improvements of caffeine in habitual con-
sumers and habitual non-consumers of caffeine. Psychophar-
macology (Berl) 179, 813-825.</sub></li>
<li><sub>[81] Hameleers PA, Van Boxtel MP, Hogervorst E, Riedel WJ,
Houx PJ, Buntinx F, Jolles J (2000) Habitual caffeine con-
sumption and its relation to memory, attention, planning
capacity and psychomotor performance across multiple age
groups. Hum Psychopharmacol 15, 573-581.</sub></li>
<li><sub>[82] Smith AP (2009) Caffeine, cognitive failures and health in a
non-working community sample. Hum Psychopharmacol 24,
29-34.</sub></li>
<li>Smith, A. (2002). Effects of caffeine on human behavior. Food and chemical toxicology, 40, 1243-1255. <a href="https://pdf.sciencedirectassets.com/271257/1-s2.0-S0278691500X01676/1-s2.0-S0278691502000960/main.pdf?X-Amz-Security-Token=IQoJb3JpZ2luX2VjECUaCXVzLWVhc3QtMSJHMEUCIQDDzKVKwxbrYQCsu%2FU1OY%2BzMOj8nH8XNjE5bAck%2B4v42AIgM3MsVAzgXAJK7SpC3o1ZWDMnRafoNdoYx%2B%2BjkaXmUWEq0gQILhAEGgwwNTkwMDM1NDY4NjUiDEzLA4n8PFVyTdYDNSqvBMv8Fyc%2FfWKFOo6SR0blem1doGESEDvezIjUJ9ShNr6rEhuKv3hpRzVQZQlRJI4oW6Y3Pdu0Vegzt4%2ByBKxAYB5uXInV%2BEk2mpPYqdZ1rFI0vEAtKXW6Kadcz6tITwRTNXeCwdo5yn9ZNq2y42qCgeEMpJQFrxuu1qLoQiOk2V8Fpvz0UC8hy%2BelNMrLTPx%2BjWfcxLPDYQ7EenWihFQqGaBVP5xAK3O7I9szBC40JOvkacq6xbwjeTJdA4IY8jmnkR0SYUDFx2CfOG5a2SbsEuy5a1gPo3HOP%2BH1AQhELBGALhkxQBnorA3dUy8bgg6EmgK5%2FcM%2BvMzo5qaz1%2FzeRBwUZzW1DbeWyjLpMHVT6kHzL%2FZClWbNmQXNF75DWsoS6GnEe0ikX%2BjPhtqiXLLrKF31tUOIeILsTxaBxHI10VvGYj7INo4RZn0kHGdN%2FmYt9%2B9L0A%2FMDEeLZ3NZgoAISQ7W%2FUMnVb7IjozgU63dAmGi6QwQ0J7qYVwJREc5so2%2BZHWesnQ3cuaBzxN3M6QTRU3S4S3mv7Odv5hB94%2Bf4c1OuuDBlRc6hIrdaPoXISCSDJ68VVROR7z5Pca1suVT2gcCKVymWEtD%2B%2Fkrv34jK8sk6H9%2F%2Fsfithv2HBJUGatwzavQpkXO%2FXCRSvsDkxukMrDjgw%2B64udLogrK68DyeFc2jBnPqpc4j9ZyMNuMV%2BPmv0NvUb%2BBQdkN%2FZhsbxBY3Kd8QuDdprLAEEHRFLhiBF8w6PCMlQY6qQHp74TxyIkyn3cENrIXFV6rn5bmBnpb5%2B%2B6QrmCjAdjxMp%2F4oZO7b1p%2FNS76XyPWNspAwxwNCO3668qFrEB76TLb0wr4gpP8C%2BY85KyQbaeC3nBPktYm4dctSMlL%2Fh3HKjYB0lg4OKRbXm6HFhuukABn4tlU6gDgk7QG3ILzYgsnmBszqZhOrpWsHQ%2Bhv7ZRCZz3WToNslLVFZMult1%2FBNTslN8FMVYnJZD&amp;X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Date=20220610T132638Z&amp;X-Amz-SignedHeaders=host&amp;X-Amz-Expires=300&amp;X-Amz-Credential=ASIAQ3PHCVTY5YUVSGZR%2F20220610%2Fus-east-1%2Fs3%2Faws4_request&amp;X-Amz-Signature=b1ceed938d5572c88c6ae70a6fefb0ee2aebbf18eb2af1309edb7861e540e54e&amp;hash=45d0ae9bf5b1205de776938c3066ad37a0cd75695e8c27297a33d701d1861c56&amp;host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&amp;pii=S0278691502000960&amp;tid=spdf-5c3b2ad6-5a48-4cd4-bc18-ed50cd82c50f&amp;sid=04f8648e1a81c1463e382cb1db28dda21152gxrqb&amp;type=client&amp;ua=4d5758525250585c5f5a06&amp;rr=7192709918bd3ad7" rel="nofollow noreferrer">PDF</a></li>
</ul>

CC BY-SA 3.0
2012-07-26T07:32:59.087Z
added another review article (Smith, 2002).
Jeromy Anglim
CC BY-SA 3.0
2012-01-24T23:01:33.230Z
It sounds like the literature is not completely consistent. Is it fair to conclude that habituated consumers experience some performance benefits but not as great as the non-regular caffeine consumers?
Seth Rogers
CC BY-SA 4.0
2012-01-23T03:30:21.597Z
2022-06-10T17:57:11.050Z
2022-06-10T17:57:11.050Z
Jeromy Anglim
<p>I've seen a fair few studies over the while that suggest caffeine increases arousal in the short term and that for some tasks, this will also increase performance (<a href="http://www.foodinsight.org/Resources/Detail.aspx?topic=Fact_Sheet_Caffeine_and_Performance">there's a few citations here</a>).</p>

<p>However, as with most drugs, habituation leads to withdrawal effects and adjustment, so that in some senses once a person gets used to caffeine, having a regular dose of caffeine may just bring a person to something like a normal level of functioning.</p>

<p>Thus, in a general sense, 
<strong>for someone used to consuming a certain level of caffeine, does having that regular quantity increase arousal or performance over and above the level that would be obtained at that moment had the person never got in the habit of consuming caffeine in the first place?</strong></p>

CC BY-SA 3.0
2012-01-21T22:26:57.627Z
Related [skeptics question](http://skeptics.stackexchange.com/q/1706/5370).
Steven Jeuris
<psychopharmacology><arousal><habituation>
Does caffeine improve performance for habituated consumers?
Jeromy Anglim
# Does caffeine improve performance for habituated consumers?

(Asked by: username_0 on 2012-01-21)

I've seen a fair few studies over the while that suggest caffeine increases arousal in the short term and that for some tasks, this will also increase performance ([there's a few citations here](http://www.foodinsight.org/Resources/Detail.aspx?topic=Fact_Sheet_Caffeine_and_Performance)).

However, as with most drugs, habituation leads to withdrawal effects and adjustment, so that in some senses once a person gets used to caffeine, having a regular dose of caffeine may just bring a person to something like a normal level of functioning.

Thus, in a general sense,
**for someone used to consuming a certain level of caffeine, does having that regular quantity increase arousal or performance over and above the level that would be obtained at that moment had the person never got in the habit of consuming caffeine in the first place?**

**Tags:** psychopharmacology, arousal, habituation

> **Comments:**
> **username_1**: Related [skeptics question](http://skeptics.stackexchange.com/q/1706/5370).  

---

## 1 answers

### Answer by username_0 on 2012-01-23. Score: 33 | Accepted answer

### Nehligh's 2010 review

Nehlig (2010) wrote a systematic review article called "Is caffeine a cognitive enhancer?" ([link to publisher, no PDF](http://iospress.metapress.com/content/lw1630245745v088/)).
On page S89 to S90 Nehlig reviews the evidence of caffeine as a cognitive enhancer within the context of a history of caffeine consumption:

> In
> caffeine non-deprived young (20–25 years) and older subjects (50–65
> years), 250 mg caffeine slightly offset the decline in performance
> found in the placebo group on a digit span memory test. However,
> caffeine did not improve performance in the immediate word recall
> task in either age group [11]. Caffeine (12.5–100 mg) given after
> overnight abstinence improved cognitive performance in a relatively
> difficult and stressful task involving rapid visual information
> processing and using a high load of working memory in 11 males and 12
> females, aged 18–56 years. The effect was more marked in individuals
> with a high habitual caffeine intake [78]. In 68 volunteers
> consuming a regular daily amount of caffeine, 2 mg/kg caffeine
> improved the speed of encoding new information in a categorical search
> task [79]. Likewise, in a study comparing 24 non-consumers (20
> mg/day) to 24 consumers of caffeine (217 mg/day), there was no
> baseline difference between group performances. Caffeine improved
> numeric working memory reaction time and sentence verification
> accuracy; alertness was also increased, but in general caffeine tended
> to improve more the performance in non consumers [80].
>
> In adult
> subjects, a higher habitual caffeine intake with no additional
> caffeine administration on the day of testing was positively related
> to better performance on incidental verbal learning and visuospatial
> learning tasks [15]. There was also an association between estimated
> caffeine intake and performance in a choice reaction time task, and in
> delayed recall of a verbal word learning task [81]. In the former
> study, older sub- jects appeared to benefit more from higher caffeine
> intake [15], while this was not the case in the latter study [81].
> Also, in real life activities, regular caffeine consumption might
> benefit cognitive functioning in a non-working population [82].

### Smith's 2002 review

Another good review is provided by Smith (2002, [PDF](http://intraspec.ca/Effects-of-caffeine-on-human-health.pdf)).
The main claim relevant to the present question argues that coffee remains beneficial despite habituation:

> It has been claimed that the positive eﬀects of caﬀeine really reﬂect
> removal of negative eﬀects of caﬀeine withdrawal. This view cannot
> account for eﬀects observed in non-consumers or nondeprived
> individuals. In addition, there is little evidence of caﬀeine
> withdrawal impairing tasks which show improvements following ingestion
> of caﬀeine.

The article is worth reading if you want to read about the relevant empirical evidence and some of the limitations of existing research.

### References:

* [11] Rees K, Allen D, Lader M (1999) The influences of age and
  caffeine on psychomotor and cognitive function. Psychophar-
  macology (Berl) 145, 181-188.
* [78] Smit HJ, Rogers PJ (2000) Effects of low doses of caffeine
  on cognitive performance, mood and thirst in low and higher
  caffeine consumers. Psychopharmacology (Berl) 152, 167-
  173.
* [80] Haskell CF, Kennedy DO, Wesnes KA, Scholey AB (2005)
  Cognitive and mood improvements of caffeine in habitual con-
  sumers and habitual non-consumers of caffeine. Psychophar-
  macology (Berl) 179, 813-825.
* [81] Hameleers PA, Van Boxtel MP, Hogervorst E, Riedel WJ,
  Houx PJ, Buntinx F, Jolles J (2000) Habitual caffeine con-
  sumption and its relation to memory, attention, planning
  capacity and psychomotor performance across multiple age
  groups. Hum Psychopharmacol 15, 573-581.
* [82] Smith AP (2009) Caffeine, cognitive failures and health in a
  non-working community sample. Hum Psychopharmacol 24,
  29-34.
* Smith, A. (2002). Effects of caffeine on human behavior. Food and chemical toxicology, 40, 1243-1255. [PDF](https://pdf.sciencedirectassets.com/271257/1-s2.0-S0278691500X01676/1-s2.0-S0278691502000960/main.pdf?X-Amz-Security-Token=IQoJb3JpZ2luX2VjECUaCXVzLWVhc3QtMSJHMEUCIQDDzKVKwxbrYQCsu%2FU1OY%2BzMOj8nH8XNjE5bAck%2B4v42AIgM3MsVAzgXAJK7SpC3o1ZWDMnRafoNdoYx%2B%2BjkaXmUWEq0gQILhAEGgwwNTkwMDM1NDY4NjUiDEzLA4n8PFVyTdYDNSqvBMv8Fyc%2FfWKFOo6SR0blem1doGESEDvezIjUJ9ShNr6rEhuKv3hpRzVQZQlRJI4oW6Y3Pdu0Vegzt4%2ByBKxAYB5uXInV%2BEk2mpPYqdZ1rFI0vEAtKXW6Kadcz6tITwRTNXeCwdo5yn9ZNq2y42qCgeEMpJQFrxuu1qLoQiOk2V8Fpvz0UC8hy%2BelNMrLTPx%2BjWfcxLPDYQ7EenWihFQqGaBVP5xAK3O7I9szBC40JOvkacq6xbwjeTJdA4IY8jmnkR0SYUDFx2CfOG5a2SbsEuy5a1gPo3HOP%2BH1AQhELBGALhkxQBnorA3dUy8bgg6EmgK5%2FcM%2BvMzo5qaz1%2FzeRBwUZzW1DbeWyjLpMHVT6kHzL%2FZClWbNmQXNF75DWsoS6GnEe0ikX%2BjPhtqiXLLrKF31tUOIeILsTxaBxHI10VvGYj7INo4RZn0kHGdN%2FmYt9%2B9L0A%2FMDEeLZ3NZgoAISQ7W%2FUMnVb7IjozgU63dAmGi6QwQ0J7qYVwJREc5so2%2BZHWesnQ3cuaBzxN3M6QTRU3S4S3mv7Odv5hB94%2Bf4c1OuuDBlRc6hIrdaPoXISCSDJ68VVROR7z5Pca1suVT2gcCKVymWEtD%2B%2Fkrv34jK8sk6H9%2F%2Fsfithv2HBJUGatwzavQpkXO%2FXCRSvsDkxukMrDjgw%2B64udLogrK68DyeFc2jBnPqpc4j9ZyMNuMV%2BPmv0NvUb%2BBQdkN%2FZhsbxBY3Kd8QuDdprLAEEHRFLhiBF8w6PCMlQY6qQHp74TxyIkyn3cENrIXFV6rn5bmBnpb5%2B%2B6QrmCjAdjxMp%2F4oZO7b1p%2FNS76XyPWNspAwxwNCO3668qFrEB76TLb0wr4gpP8C%2BY85KyQbaeC3nBPktYm4dctSMlL%2Fh3HKjYB0lg4OKRbXm6HFhuukABn4tlU6gDgk7QG3ILzYgsnmBszqZhOrpWsHQ%2Bhv7ZRCZz3WToNslLVFZMult1%2FBNTslN8FMVYnJZD&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20220610T132638Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=ASIAQ3PHCVTY5YUVSGZR%2F20220610%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=b1ceed938d5572c88c6ae70a6fefb0ee2aebbf18eb2af1309edb7861e540e54e&hash=45d0ae9bf5b1205de776938c3066ad37a0cd75695e8c27297a33d701d1861c56&host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&pii=S0278691502000960&tid=spdf-5c3b2ad6-5a48-4cd4-bc18-ed50cd82c50f&sid=04f8648e1a81c1463e382cb1db28dda21152gxrqb&type=client&ua=4d5758525250585c5f5a06&rr=7192709918bd3ad7)

> **Comments:**
> **username_2**: It sounds like the literature is not completely consistent. Is it fair to conclude that habituated consumers experience some performance benefits but not as great as the non-regular caffeine consumers?  
> **username_0**: added another review article (Smith, 2002).  

---

