Do antidepressants, anxiolytics and sleeping pills significantly affect the intelligence of a person, for example as expressed by the general (g) factor? Do these compounds affect the g factor each individually? And what about the combinations of the two or three of them?

To narrow down the scope of the question, if necessary, we can go for commonly encountered drugs like Duloxetine (antidepressant), Xanax (anxiolytic), and Zolpidem (hypnotic/sedative).

I did a Google search, but the results were not that satisfying. I couldn't find a reliable resource which properly treats the topic.

  • $\begingroup$ The previous question might have been formulated too much like a self-help question. I do need to give you an heads up that here at CogSci we do not have many psychiatric experts who are knowledgeable about the interaction between medication and cognition. There is thus a chance you will not receive an answer here. I'd advice to read the brochure of the medication or ask a medical professional indeed. Those may be your best bets for finding the answer. $\endgroup$ – Robin Kramer May 12 '17 at 6:41
  • $\begingroup$ @OpenBall It would be better to indicate why you are asking this question, because the answer may depend very much on the objectives to carry it out. $\endgroup$ – hexadecimal Jun 22 '17 at 19:02
  • $\begingroup$ @hexadecimal well, I had to take all of these and happened to have a decline in my intelligence. I am trying to pin down the cause. $\endgroup$ – user14575 Jun 22 '17 at 19:03
  • $\begingroup$ @RobinKramer Everyone who has studied psychology has had at least 3 drug-related subjects, including psychopharmacology. $\endgroup$ – hexadecimal Jun 22 '17 at 19:04
  • $\begingroup$ @OpenBall OK I was wondering if it was for research, I'll work on the answer, but surely it's a performance decrease, these medicaments do not generally harm the intelligence and less in the short term. $\endgroup$ – hexadecimal Jun 22 '17 at 19:18

About intelligence: The subject of intelligence is broadly addressed in research in psychology, one of the most supportive theories is Spearman's bifactorial theory of intelligence, in this theory the factor g is a huge stable factor that explains the common variance (in scores) to all the different cognitive tasks that can be put to a person. Although intelligence would approach a series of constructs that explain the abilities in the resolution of cognitive problems, other factors that modulate these intelligence factors, such as motivation (volition or will) and attention (concentration), should always be taken into account. Among others (tiredness, stress, activation, etc). External factors exert their influence in early stages of information processing, can be identified with physical characteristics (light conditions, letter size, presence of the public, the person requires lenses, etc.). In conclusion, what we call intelligence, which we consider to be very stable, does not explain everything at all in cognitive tasks, there are many other causes that can influence, for example, and as mentioned, the level of activation (sleep, fatigue) or motivation and will.

Before considering an adverse drug effect, a period of adaptation should also be considered, based on factors such as: affinity (ability of the drug to match the receptor), intrinsic activity (ability to activate the receptor after its use ) And effective dose which is the amount of drug that produces the desired effect in 50% of users. In summary there is a period in which the person is adapting to the effects of the drug and even if the dose is adequate the person may experience a great change.

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Adverse effects of drugs: Adverse effects are defined as an unwanted reaction that can be sometimes harmful and permanent, (not considered adverse effect inappropriate use) a high number of people report adverse effects, it is estimated that around 10 % of people experience effects but for most benefits obtained are greater than undesirable effects.

There are different types of adverse effects (cutaneous, gastrointestinal, respiratory system, cardiovascular system), if a drug produced damage to intelligence, it would be a late cognitive adverse effect, ie it would manifest after a high time consuming drug (sometimes long after withdrawal of the drug). In relation to adverse effects in the central nervous system, the most common are: tiredness, dizziness, confusion, tremors, headache and seizures. The increase in fatigue occurs in almost all drugs that have a suppressive effect of the central nervous system (analgesics, antipsychotics, antidepressants, hypnotics, sedatives and anticonvulsants)

Depending on the country of residence, there are agencies that freely disclose information regarding the trade names with which the medicines are distributed in the state, these agencies also collect and study information about adverse effects recorded in other countries.

Duloxetine (R) (Duloxetine hydrochloride): Inhibitor of serotonin and noradrenaline reuptake. It weakly inhibits dopamine reuptake without significant affinity for histaminergic, dopaminergic, cholinergic and adrenergic receptors. Adverse effects: Headache, drowsiness, dizziness, lethargy, tremors, paraesthesia; Decreased appetite; Insomnia, agitation, decreased libido, anxiety, abnormal orgasms, abnormal dreams; blurry vision; Tinnitus; Increased blood pressure, flushing; Yawning; Nausea, dry mouth, constipation, diarrhea, abdominal pain, vomiting, dyspepsia, flatulence; Increased sweating, rash; Musculoskeletal pain, muscle spasm; Dysuria; Erectile dysfunction, ejaculation disorder, delayed ejaculation; Falls, fatigue; weightloss.

Xanax (R) (Alprazolam): It is believed to exert its effect by binding to the ester-specific receptors located in SCN. It has anxiolytic, hypnotic muscle relaxant and anticonvulsive properties, as well as a specific activity in distress crisis. Adverse effects: Depression, sedation, somnolence, ataxia, memory impairment, dysarthria, dizziness, headache; Constipation, dry mouth; Fatigue, irritability.

Zolpiden (R) (Zolpidem hemitartrate): hypnotic type non benzodiazepine. Group of Imidazopyrines. Specific agonist of central receptors belonging to the GABA-omega macromolecular receptor complex that modulates the opening of the chlorine ion channel. Adverse effects: bitterness and dry mouth, upset stomach, drowsiness, dizziness and paradoxical reaction that usually disappear with a dose adjustment.

In summary, it seems that they are drugs that, in their phase of adjustment or adaptation, may well cause a temporary reduction in cognitive performance, but this effect should be reduced and temporary, that is to say, very brief, in case the Problem persists or in case of doubt can always be accessed to make consultations to pharmacists or general medicine (even for second opinions beyond the professional who has prescribed these drugs).


  • Stephen M. Stahl. (2000). Essential Psychopharmacology: Neuroscientific Basis and Practical Applications. New York: Cambridge University Press.
  • Stephen M. Stahl. (2005). Prescriber's Guide. New York: Cambridge University Press.
  • $\begingroup$ Request here modifications or more information. $\endgroup$ – hexadecimal Jun 22 '17 at 21:39
  • $\begingroup$ hi hexadeciamal, sorry to bother you again, but it would again be great if you could include some references to back up your statement. Your answer looks amazing, is well thought out and, most importantly, is answering the question. However, without including references it is unknown whether this is factual information or based on personal experiences that may or may not be the truth. $\endgroup$ – Robin Kramer Jun 23 '17 at 9:50
  • $\begingroup$ Okay, that's right, you're right I'll include the references for the answers and I should devote more effort to the sources. However, it is also necessary to re-emphasize that there are difficulties to name some sources. For example, there are many things that I remember from my teachers, important things, knowledge of professional courses or full afternoon afternoons looking for articles whose title I do not remember. $\endgroup$ – hexadecimal Jun 23 '17 at 10:59
  • $\begingroup$ I understand that completely. I experience the same thing. What I usually try to do is do a quick google search to see if I can find the study I was looking for, or otherwise use one that states something similar. If that proves to be difficult, I sometimes allow myself to use a less-scientific source or a figure, like you did already :) $\endgroup$ – Robin Kramer Jun 23 '17 at 11:06
  • $\begingroup$ Isn't intelligence a personality trait? In this case both the question and the answer might need to be formulated more precisely. Reading above, I have the impression, that you are speaking mainly about the effect of drugs on cognitive performance. — Having two groups of subjects, one with high and the other with low IQ-scores, it seems plausible to expect different performances for each group under the effect of the same drug. In other words: I would expect both intelligence and drugs to be distinct determinants that affect cognitive performance measures. Regards. $\endgroup$ – user14074 Jun 26 '17 at 16:11

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