Posted by undopaminergic on April 24, 2008, at 15:53:44
In reply to Re: cognitive problems from solian » undopaminergic, posted by JDx on April 23, 2008, at 5:40:29
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> > No, the symptoms existed before Ritalin, which is one of the attempts to treat them.
> >
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> IMO ritalin is a bad choice in order to improve motivations.as far as i know high amount of dopamine activity doesn't reflect good working motivations but other aspects like rate of fire and pattern of fire of DA neurons, and ritalin doesn't help with that ( on the contrary)
>You may wish to review the research on this matter, as it strongly indicates an essential role of dopamine in motivation. Try these, for example:
http://www.nature.com/npp/journal/v31/n7/abs/1300966a.html
http://www.ncbi.nlm.nih.gov/pubmed/7718155> > That's interesting, as my experience with risperidone was the opposite: it made me lethargic, and more apathetic and anhedonic.
> >
> well , I make differentiation between the serotnin antagonism mechanism which makes the depression like symptoms you described, and the DA (and NE) mechanism which has the antipsychotic effect which fix the motivations aspects-
>It's true that the DA antagonism is an important antipsychtoic mechanism, but I'm almost certain that it also accounts for what you call "depression like symptoms" (they may be even more like negative symptoms of schizophrenia) and it also produces parkinsonian (extrapyramidal) symptoms at higher doses. By contrast, psychostimulants such as methylphenidate (Ritalin) and amphetamine, as well as low doses of sulpiride and amisulpride that enhance dopamergic neurotransmission, increase motivation, or goal-directed activity.
The blockade of 5-HT2 serotonin receptors by risperidone and most other atypical antipsychotics is considered desirable, and has antidepressant-like effects in some animal models (forced swim test) of depression and negative schizophrenic symptoms. Some antidepressants block the 5-HT2 receptor too (e.g. mirtazapine), and atypical antipsychotics are sometimes combined with antidepressants in an effort to improve efficacy.
> that in my experience reflects in me having additional value to perception of things ie-when i am taking Risperdal I really have sexual desire towards women , i really enjoy watching women, curiosity to learn things, and excitments from little things;
>Some people do experience increased interest in certain things as a result of risperidone. I can't say that I noticed anything of the kind.
> though it decreases my mood and makes me feel depressed - which makes me low energy , not happy etc..
>That is unsurprising.
> > Yes, but in my experience it improves motivation - at least until tolerance develops. The drug tends to lose it efficacy, necessitating "drug holidays" to restore effectiveness.
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> As far as i know tolerance doesn't develops with ritalin (otherwise you would need to increase ritalin dosage every few months).
>Yes, indeed, I have to increase the dose at weekly intervals or less, until I reach 40 mg per dose (or 108 mg of Concerta, a prolonged release formulation of methylphenidate), which can be sustained for approximately a month, after which almost all effect is lost. Apparently, the dose-reponse curve flattens at that point, as further dose increases have little effect.
> Mybe because it has short half-life , and DA receptors in the brain has time reAdjust at night when no ritalin in your blood..
>That may be true if you take only one dose of immediate release methylphenidate, but that's not enough to maintain effectiveness for a whole day.
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thread:823096
URL: http://www.dr-bob.org/babble/20080420/msgs/825215.html