Dopamine hypothesis of schizophrenia - wikipedia Dopamine hypothesis of schizophrenia This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( August 2009 ) The dopamine hypothesis of schizophrenia or the dopamine hypothesis of psychosis is a model that attributes symptoms of schizophrenia ( like psychoses ) to a disturbed and hyperactive dopaminergic signal transduction. The model draws evidence from the observation that a large number of antipsychotics have dopamine - receptor antagonistic effects. The theory, however, does not posit dopamine overabundance as a complete explanation for schizophrenia. Rather, the overactivation of D2 receptors, specifically, is one effect of the global chemical synaptic dysregulation observed in this disorder. Contents 1 Introduction 2 Discussion 2.1 Evidence for the dopamine hypothesis 2.2 Evidence against the dopamine hypothesis 2.3 Relationship with glutamate 2.4 Criticisms 3 See also 4 References 5 External links Introduction Some researchers have suggested that dopamine systems in the mesolimbic pathway may contribute to the ' positive symptoms ' of schizophrenia ( whereas problems with dopamine function in the mesocortical pathway may be responsible for the ' negative symptoms ', such as avolition and alogia ). Abnormal expression, thus distribution of the D receptor between these areas and the rest of the brain may also be implicated in schizophrenia, specifically in the acute phase. A relative excess of these receptors within the limbic system means Broca 's area, which can produce illogical language, has an abnormal connection to Wernicke 's area, which comprehends language but does not create it. Note that variation in distribution is observed within individuals, so abnormalities of this characteristic likely play a significant role in all psychological illnesses. Individual alterations are produced by differences within glutamatergic pathways within the limbic system, which are also implicated in other psychotic syndromes. Among the alterations of both synaptic and global structure, the most significant abnormalities are observed in the uncinate fasciculus and the cingulate cortex. The combination of these creates a profound dissymmetry of prefrontal inhibitory signaling, shifted positively towards the dominant side. Eventually, the cingulate gyrus becomes atrophied towards the anterior, due to long - Term Depression ( LTD ) and Long - Term Potentiation ( LTP ) from the abnormally strong signals transversely across the brain. This, combined with a relative deficit in GABAergic input to Wernicke 's area, shifts the balance of bilateral communication across the corpus callosum posteriorly. Through this mechanism, hemispherical communication becomes highly shifted towards the left / dominant posterior. As such, spontaneous language from Broca 's can propagate through the limbic system to the tertiary auditory cortex. This retrograde signaling to the temporal lobes that results in the parietal lobes not recognizing it as internal results in the auditory hallucinations typical of chronic schizophrenia. In addition, significant cortical grey matter volume reductions are observed in this disorder. Specifically, the right hemisphere atrophies more, while both sides show a marked decrease in frontal and posterior volume. This indicates that abnormal synaptic plasticity occurs, where certain feedback loops become so potentiated, others receive little glutaminergic transmission. This is a direct result of the abnormal dopaminergic input to the striatum, thus ( indirectly ) disinhibition of thalamic activity. The excitatory nature of dopaminergic transmission means the glutamate hypothesis of schizophrenia is inextricably intertwined with this altered functioning. 5 - HT also regulates monoamine neurotransmitters, including dopaminergic transmission. Specifically, the 5 - HT2A receptor regulates cortical input to the basal ganglia and many typical and atypical antipsychotics are antagonists at this receptor. Several antipsychotics are also antagonists at the 5 - HT2C receptor, leading to dopamine release in the structures where 5 - HT2C is expressed ; striatum, prefrontal cortex, nucleus accumbens, amygdala, hippocampus ( all structures indicated in this disease ), and currently thought to be a reason why antipsychotics with 5HT2C antagonistic properties improves negative symptoms. More research is needed to explain the exact nature of the altered chemical transmission in this disorder. Recent evidence on a variety of animal models of psychosis, such as sensitization of animal behaviour by amphetamine, or phencyclidine ( PCP, Angel Dust ), or excess steroids, or by removing various genes ( COMT, DBH, GPRK6, RGS9, RIIbeta ), or making brain lesions in newborn animals, or delivering animals abnormally by Caesarian section, all induce a marked behavioural supersensitivity to dopamine and a marked rise in the number of dopamine D receptors in the high - affinity state for dopamine. This latter work implies that there are multiple genes and neuronal pathways that can lead to psychosis and that all these multiple psychosis pathways converge via the high - affinity state of the D2 receptor, the common target for all antipsychotics, typical or atypical. Combined with less inhibitory signalling from the thalamus and other basal ganglic structures, from hyoptrophy the abnormal activation of the cingulate cortex, specifically around Broca 's and Wernicke 's areas, abnormal D agonism can facilitate the self - reinforcing, illogical patterns of language found in such patients. In schizophrenia, this feedback loop has progressed, which produced the widespread neural atrophy characteristic of this disease. Patients on neuroleptic or antipsychotic medication have significantly less atrophy within these crucial areas. As such, early medical intervention is crucial in preventing the advancement of these profound deficits in bilateral communication at the root of all psychotic disorders. Advanced, chronic schizophrenia can not respond even to clozapine, regarded as the most potent antipsychotic, as such, a cure for highly advanced schizophrenia is likely impossible, so the value of early intervention can not be stressed enough. Discussion Evidence for the dopamine hypothesis Amphetamine, cocaine and similar drugs increase levels of dopamine in the brain and can cause symptoms which resemble those present in psychosis, particularly after large doses or prolonged use. This is often referred to as `` amphetamine psychosis '' or `` cocaine psychosis, '' but may produce experiences virtually indistinguishable from the positive symptoms associated with schizophrenia. Similarly, those treated with dopamine enhancing levodopa for Parkinson 's disease can experience psychotic side effects mimicking the symptoms of schizophrenia. Up to 75 % of patients with schizophrenia have increased signs and symptoms of their psychosis upon challenge with moderate doses of methylphenidate or amphetamine or other dopamine - like compounds, all given at doses at which control normal volunteers do not have any psychologically disturbing effects. Some functional neuroimaging studies have also shown that, after taking amphetamine, patients diagnosed with schizophrenia show greater levels of dopamine release ( particularly in the striatum ) than non-psychotic individuals. However, the acute effects of dopamine stimulants include euphoria, alertness and over-confidence ; these symptoms are more reminiscent of mania than schizophrenia. Since the 2000s, several PET studies have confirmed an altered synthesis capacity of dopamine in the nigrostriatal system demonstrating a dopaminergic dysregulation. A group of drugs called the phenothiazines, including antipsychotics such as chlorpromazine, has been found to antagonize dopamine binding ( particularly at receptors known as D dopamine receptors ) and reduce positive psychotic symptoms. This observation was subsequently extended to other antipsychotic drug classes, such as butyrophenones including haloperidol. The link was strengthened by experiments in the 1970s which suggested that the binding affinity of antipsychotic drugs for D dopamine receptors seemed to be inversely proportional to their therapeutic dose. This correlation, suggesting that receptor binding is causally related to therapeutic potency, was reported by two laboratories in 1976. Genetic evidence has suggested that there may be genes, or specific variants of genes, that code for mechanisms involved in dopamine function, which may be more prevalent in people experiencing psychosis or diagnosed with schizophrenia. Dopamine related genes linked to psychosis in this way include COMT, DRD4, and AKT1. People with Schizophrenia appear to have a high rate of self - medication with nicotine ; the therapeutic effect likely occurs through dopamine modulation by nicotinic acetylcholine receptors. However, there was controversy and conflicting findings over whether postmortem findings resulted from drug tolerance to chronic antipsychotic treatment. Compared to the success of postmortem studies in finding profound changes of dopamine receptors, imaging studies using SPET and PET methods in drug naive patients have generally failed to find any difference in dopamine D receptor density compared to controls. Comparable findings in longitudinal studies show : `` Particular emphasis is given to methodological limitations in the existing literature, including lack of reliability data, clinical heterogeneity among studies, and inadequate study designs and statistic, '' suggestions are made for improving future longitudinal neuroimaging studies of treatment effects in schizophrenia A recent review of imaging studies in schizophrenia shows confidence in the techniques, while discussing such operator error. In 2007 one report said, `` During the last decade, results of brain imaging studies by use of PET and SPET in schizophrenic patients showed a clear dysregulation of the dopaminergic system. '' Recent findings from meta - analyses suggest that there may be a small elevation in dopamine D receptors in drug - free patients with schizophrenia, but the degree of overlap between patients and controls makes it unlikely that this is clinically meaningful. While the review by Laruelle acknowledged more sites were found using methylspiperone, it discussed the theoretical reasons behind such an increase ( including the monomer - dimer equilibrium ) and called for more work to be done to ' characterise ' the differences. In addition, newer antipsychotic medication ( called atypical antipsychotic medication ) can be as potent as older medication ( called typical antipsychotic medication ) while also affecting serotonin function and having somewhat less of a dopamine blocking effect. In addition, dopamine pathway dysfunction has not been reliably shown to correlate with symptom onset or severity. HVA levels correlate trendwise to symptoms severity. During the application of debrisoquin, this correlation becomes significant. Giving a more precise explanation of this discrepancy in D receptor has been attempted by a significant minority. Radioligand imaging measurements involve the monomer and dimer ratio, and the ' cooperativity ' model. Cooperativitiy is a chemical function in the study of enzymes. Dopamine receptors interact with their own kind, or other receptors to form higher order receptors such as dimers, via the mechanism of cooperativity. Philip Seeman has said : `` In schizophrenia, therefore, the density of ( 11C ) methylspiperone sites rises, reflecting an increase in monomers, while the density of ( 11C ) raclopride sites remains the same, indicating that the total population of D monomers and dimers does not change. '' ( In another place Seeman has said methylspiperone possibly binds with dimers ) With this difference in measurement technique in mind, the above - mentioned meta - analysis uses results from 10 different ligands. Exaggerated ligand binding results such as SDZ GLC 756 ( as used in the figure ) were explained by reference to this monomer - dimer equilibrium. According to Seeman, ``... Numerous postmortem studies have consistently revealed D receptors to be elevated in the striata of patients with schizophrenia ''. However, the authors were concerned the effect of medication may not have been fully accounted for. The study introduced an experiment by Abi - Dargham et al. in which it was shown medication - free live schizophrenics had more D receptors involved in the schizophrenic process and more dopamine. Since then another study has shown such elevated percentages in D receptors is brain - wide ( using a different ligand, which did not need dopamine depletion ). In a 2009 study, Annisa Abi - Dagham et al. confirmed the findings of her previous study regarding increased baseline D receptors in schizophrenics and showing a correlation between this magnitude and the result of amphetamine stimulation experiments. Some animal models of psychosis are similar to those for addiction -- displaying increased locomotor activity. For those female animals with previous sexual experience, amphetamine stimulation happens faster than for virgins. There is no study on male equivalent because the studies are meant to explain why females experience addiction earlier than males. Even in 1986 the effect of antipsychotics on receptor measurement was controversial. An article in Science sought to clarify whether the increase was solely due to medication by using drug - naive schizophrenics : `` The finding that D dopamine receptors are substantially increased in schizophrenic patients who have never been treated with neuroleptic drugs raises the possibility that dopamine receptors are involved in the schizophrenic disease process itself. Alternatively, the increased D receptor number may reflect presynaptic factors such as increased endogenous dopamine levels ( 16 ). In either case, our findings support the hypothesis that dopamine receptor abnormalities are present in untreated schizophrenic patients. '' ( The experiment used 3 - N - ( 11C ) methylspiperone -- the same as mentioned by Seeman detects D monomers and binding was double that of controls. ) It is still thought that dopamine mesolimbic pathways may be hyperactive, resulting in hyperstimulation of D receptors and positive symptoms. There is also growing evidence that, conversely, mesocortical pathway dopamine projections to the prefrontal cortex might be hypoactive ( underactive ), resulting in hypostimulation of D receptors, which may be related to negative symptoms and cognitive impairment. The overactivity and underactivity in these different regions may be linked, and may not be due to a primary dysfunction of dopamine systems but to more general neurodevelopmental issues that precede them. Increased dopamine sensitivity may be a common final pathway. Another finding is a six-fold excess of binding sites insensitive to the testing agent, raclopride ; Seeman said this increase was probably due to the increase in D monomers. Such an increase in monomers may occur via the cooperativity mechanism which is responsible for D and D, the supersensitive and lowsensitivity states of the D dopamine receptor. More specifically, `` an increase in monomers, may be one basis for dopamine supersensitivity ''. Evidence against the dopamine hypothesis Further experiments, conducted as new methods were developed ( particularly the ability to use PET scanning to examine drug action in the brain of living patients ) challenged the view that the amount of dopamine blocking was correlated with clinical benefit. These studies showed that some patients had over 90 % of their D receptors blocked by antipsychotic drugs, but showed little reduction in their psychoses. This primarily occurs in patients who have had the psychosis for ten to thirty years. At least 90 - 95 % of first - episode patients, however, respond to antipsychotics at low doses and do so with D occupancy of 60 - 70 %. The antipsychotic aripiprazole occupies over 90 % of D receptors, but this drug is both an agonist and an antagonist at D receptors. Furthermore, although dopamine - inhibiting medications modify dopamine levels within minutes, the associated improvement in patient symptoms is usually not visible for at least several days, suggesting that dopamine may be indirectly responsible for the illness. Similarly, a new generation of antipsychotic drugs ( called the atypical antipsychotics ) were found to be just as effective as older typical antipsychotic drugs in controlling psychosis, but more effective in controlling the negative symptoms, despite the fact that they have lower affinity for dopamine receptors than for various other neurotransmitter receptors. More recent work, however, has shown that atypical antipsychotic drugs such as clozapine and quetiapine bind and unbind rapidly and repeatedly to the dopamine D receptor. All of these drugs exhibit inverse agonistic effects at the 5 - HT receptors, meaning serotonin abnormalities are also involved in the complex constellation of neurologic factors predisposing one to the self reinforcing language - based psychological deficits found in all forms of psychosis. The excitatory neurotransmitter glutamate is now also thought to be associated with schizophrenia. Phencyclidine ( also known as PCP or `` Angel Dust '' ) and ketamine, both of which block glutamate ( NMDA ) receptors, are known to cause psychosis at least somewhat resembling schizophrenia, further suggesting that psychosis and perhaps schizophrenia can not fully be explained in terms of dopamine function, but may also involve other neurotransmitters. Similarly, there is now evidence to suggest there may be a number of functional and structural anomalies in the brains of some people diagnosed with schizophrenia, such as changes in grey matter density in the frontal and temporal lobes. It appears, therefore, that there are multiple causes for psychosis and schizophrenia, including gene mutations and anatomical lesions. Psychiatrist David Healy has argued that drug companies have inappropriately promoted the dopamine hypothesis of schizophrenia as a deliberate and calculated simplification for the benefit of drug marketing. Relationship with glutamate Research has shown the importance of glutamate receptors, specifically N - methyl - D - aspartate receptors ( NMDARs ), in addition to dopamine in the etiology of schizophrenia. Mice with only 5 % of the normal levels of NMDAR 's expressed schizophrenic like behaviors seen in animal models of schizophrenia while mice with 100 % of NMDAR 's behaved normally. Schizophrenic behavior in low NMDAR mice has been effectively treated with antipsychotics that lower dopamine. NMDAR 's and dopamine receptors in the prefrontal cortex are associated with the cognitive impairments and working memory deficits commonly seen in schizophrenia. Rats that have been given a NMDAR antagonist exhibit a significant decrease in performance on cognitive tasks. Rats given a dopamine antagonist ( antipsychotic ) experience a reversal of the negative effects of the NMDAR antagonist. Glutamate imbalances appear to cause abnormal functioning in dopamine. When levels of glutamate are low dopamine is overactive and results in the expression schizophrenic symptoms. People with Schizophrenia also have a higher incidence of nicotine use than those without schizophrenia. The high rate of use may be a form of self - medication that reduces negative symptoms by increasing the activity of glutamate and lowering the activity of dopamine. Elevated activation in the prefrontal cortex from nicotine use can increase focus and cognitive performance which are impaired in people with schizophrenia. Activation of nicotinic acetylcholine receptors in mice has been shown to increase glutamate levels in the prefrontal cortex and may help to decrease the cognitive deficits seen in schizophrenia. In addition, nicotine is thought to help regulate dopamine release. Nicotine acts as an agonist to nicotinic acetylcholine receptors which then increases the release of dopamine. However, prolonged use of nicotine causes a diminished response to nicotine thus lowering dopamine levels long term. Nicotine use may be higher in people with schizophrenia because it helps to balance levels of glutamate and dopamine in the brain causing a reduction in some negative symptoms. Criticisms Dr Ronald Pies, the current editor in Chief Emeritus of Psychiatric Times with a circulation of about 50,000 psychiatrists monthly, wrote on July 11, 2011 `` In truth, the `` chemical imbalance '' notion was always a kind of urban legend - - never a theory seriously propounded by well - informed psychiatrists. '' See also Causes of schizophrenia Glutamate hypothesis of schizophrenia Latent inhibition References Jump up ^ Carlson, Neil R. ( 2013 ). Physiology of behavior ( 11th ed. ). Boston : Pearson. ISBN 0205239390. Jump up ^ McIntosh AM, Maniega SM, Lymer GK, McKirdy J, Hall J, Sussman JE, Bastin ME, Clayden JD, et al. ( 2008 ). `` White matter tractography in bipolar disorder and schizophrenia ''. Biological Psychiatry. 64 ( 12 ) : 1088 -- 1092. doi : 10.1016 / j. biopsych. 2008.07. 026. PMID 18814861. ^ Jump up to : Haznedar MM Buchsbaum MS Hazletta EA Shihabuddina L Newa A Sieverasa LJ ( 2004 ). `` Cingulate gyrus volume and metabolism in the schizophrenia spectrum ''. Schizophrenia Research. 71 ( 2 -- 3 ) : 249 -- 262. doi : 10.1016 / j. schres. 2004.02. 025. PMID 15474896. Jump up ^ Schlaug G Marchina S Norton A ( 2009 ). `` Evidence for plasticity in white - matter tracts of patients with chronic Broca 's aphasia undergoing intense intonation - based speech therapy ''. Annals of the New York Academy of Sciences. 1169 ( 1 ) : 385 -- 94. Bibcode : 2009NYASA1169... 385S. doi : 10.1111 / j. 1749 - 6632.2009. 04587. x. PMC 2777670. PMID 19673813. Jump up ^ Nakamura M, McCarley RW, Kubicki M, Dickey CC, Niznikiewicz MA, Voglmaier MM, Seidman LJ, Maier SE, et al. ( 2005 ). `` Fronto - temporal disconnectivity in schizotypal personality disorder : a diffusion tensor imaging study ''. Biological Psychiatry. 58 ( 6 ) : 468 -- 478. doi : 10.1016 / j. biopsych. 2005.04. 016. PMC 2768055. PMID 15978550. Jump up ^ Friston KJ The disconnection hypothesis, 1998 Jump up ^ Harvey I Ron MA Du Boulay G Wicks D Lewis SW Murray RM ( 1993 ). `` Reduction of cortical volume in schizophrenia on magnetic resonance imaging ''. Psychological Medicine. 23 ( 3 ) : 591 -- 604. doi : 10.1017 / S003329170002537X. PMID 8234567. Jump up ^ Carlsson M. ; Carlsson A. ( 1990 ). `` Schizophrenia : A Sub cortical Neurotransmitter Imbalance Syndrome ? ''. Schizophrenia Bulletin. 16 ( 3 ) : 425 -- 430. doi : 10.1093 / schbul / 16.3. 425. ^ Jump up to : Seeman, P. ; Weinshenker, D. ; Quirion, R. ; Srivastava, K. ; Bhardwaj, K. ; Grandy, K. ; Premont, T. ; Sotnikova, D. ; Boksa, P. ; El - Ghundi, M. ; O'Dowd, B.F. ; George, S.R. ; Perreault, M.L. ; Männistö, P.T. ; Robinson, S. ; Palmiter, R.D. ; Tallerico, T. ( Mar 2005 ). `` Dopamine supersensitivity correlates with D2High states, implying many paths to psychosis '' ( Free full text ). Proceedings of the National Academy of Sciences of the United States of America. 102 ( 9 ) : 3513 -- 3518. Bibcode : 2005PNAS... 102.3513 S. doi : 10.1073 / pnas. 0409766102. ISSN 0027 - 8424. PMC 548961. PMID 15716360. ^ Jump up to : Gur RE Maany V Mozley PD Swanson C Wilker W Ruben C ( 1998 ). `` Subcortical MRI Volumes in Neuroleptic - Naive and Treated Patients With Schizophrenia ''. American Journal of Psychiatry. 155 ( 12 ) : 1711 -- 1717. doi : 10.1176 / ajp. 155.12. 1711. PMID 9842780. Jump up ^ Arinami T Gao M Hamaguchi H Toru M ( 1997 ). `` A functional polymorphism in the promoter region of the dopamine D2 receptor gene is associated with schizophrenia ''. Human Molecular Genetics. 6 ( 4 ) : 577 -- 582. doi : 10.1093 / hmg / 6.4. 577. PMID 9097961. Jump up ^ Whitford TJ, Kubicki M, Schneiderman JS, O'Donnell LJ, King R, Alvarado JL, Khan U, et al. ( 2010 ). `` Corpus callosum abnormalities and their association with psychotic symptoms in patients with schizophrenia ''. Biological Psychiatry. 68 ( 1 ) : 70 -- 77. doi : 10.1016 / j. biopsych. 2010.03. 025. PMC 2900500. PMID 20494336. Jump up ^ McEvoy JP, Lieberman JA, Stroup TS, Davis SM, Meltzer HY, Rosenheck RA, Swartz MS, et al. ( 2006 ). `` Effectiveness of Clozapine Versus Olanzapine, Quetiapine, and Risperidone in Patients With Chronic Schizophrenia Who Did Not Respond to Prior Atypical Antipsychotic Treatment ''. American Journal of Psychiatry. 163 ( 4 ) : 600 -- 610. doi : 10.1176 / appi. ajp. 163.4. 600. PMID 16585434. Jump up ^ Lieberman, J.A. ; Kane, J.M. ; Alvir, J. ( 1987 ). `` Provocative tests with psychostimulant drugs in schizophrenia ''. Psychopharmacology. 91 ( 4 ) : 415 -- 433. doi : 10.1007 / BF00216006. PMID 2884687. Jump up ^ Curran, C. ; Byrappa, N. ; McBride, A. ( Sep 2004 ). `` Stimulant psychosis : systematic review '' ( Free full text ). The British Journal of Psychiatry. 185 ( 3 ) : 196 -- 204. doi : 10.1192 / bjp. 185.3. 196. ISSN 0007 - 1250. PMID 15339823. Jump up ^ Jacobs D, Silverstone T ( May 1986 ). `` Dextroamphetamine - induced arousal in human subjects as a model for mania ''. Psychological Medicine. 16 ( 2 ) : 323 -- 329. doi : 10.1017 / S0033291700009132. ISSN 0033 - 2917. PMID 3726006. Jump up ^ Weinstein, Jodi J. ; Chohan, Muhammad O. ; Slifstein, Mark ; Kegeles, Lawrence S. ; Moore, Holly ; Abi - Dargham, Anissa ( 2017 - 01 - 01 ). `` Pathway - Specific Dopamine Abnormalities in Schizophrenia ''. Biological Psychiatry. 81 ( 1 ) : 31 -- 42. doi : 10.1016 / j. biopsych. 2016.03. 2104. ISSN 1873 - 2402. PMC 5177794. PMID 27206569. Jump up ^ Creese I, Burt DR, Snyder SH ( April 1976 ). `` Dopamine receptor binding predicts clinical and pharmacological potencies of antischizophrenic drugs ''. Science. 192 ( 4238 ) : 481 -- 3. Bibcode : 1976Sci... 192... 481C. doi : 10.1126 / science. 3854. PMID 3854. Jump up ^ Seeman, P. ; Lee, T. ; Chau - wong, M. ; Wong, K. ( 1976 ). `` Antipsychotic drug doses and neuroleptic / dopamine receptors ''. Nature. 261 ( 5562 ) : 717 -- 719. Bibcode : 1976Natur. 261... 717S. doi : 10.1038 / 261717a0. PMID 945467. Jump up ^ Arguello, A. ; Gogos, A. ( Jun 2008 ). `` A signaling pathway AKTing up in schizophrenia ''. The Journal of Clinical Investigation ( Free full text ). 118 ( 6 ) : 2018 -- 2021. doi : 10.1172 / JCI35931. ISSN 0021 - 9738. PMC 2391280. PMID 18497888. Jump up ^ Davis C, Jeste D, Eyler L. Review of longitudinal functional neuroimaging studies of drug treatments in patients with schizophrenia. Schizophrenia Research. 1 October 2005 ; 78 ( 1 ) : 45 -- 60. doi : 10.1016 / j. schres. 2005.05. 009. PMID 15979287. Jump up ^ Gur RE, Chin S. Laterality in functional brain imaging studies of schizophrenia... Schizophrenia bulletin. 1999 ; 25 ( 1 ) : 141 -- 56. doi : 10.1093 / oxfordjournals. schbul. a033361. PMID 10098918. Jump up ^ Meisenzahl EM, Schmitt GJ, Moller HJ. The role of dopamine for the pathophysiology of schizophrenia. International Review of Psychiatry. 2007 ; 19 ( 4 ) : 337 -- 45. doi : 10.1080 / 09540260701502468. PMID 17671867. Jump up ^ Laruelle M. Imaging dopamine transmission in schizophrenia. A review and meta - analysis. QJ Nucl Med. 1998 ; 42 ( 3 ) : 211 -- 21. PMID 9796369. Jump up ^ Stone JM, Morrison PD, Pilowsky LS. Review : Glutamate and dopamine dysregulation in schizophrenia a synthesis and selective review. Journal of Psychopharmacology. 2006 ; 21 ( 4 ) : 440 -- 52. doi : 10.1177 / 0269881106073126. PMID 17259207. Jump up ^ Maas JW, Contreras SA, Seleshi E, Bowden CL. Dopamine metabolism and disposition in schizophrenic patients. Studies using debrisoquin. Arch Gen Psychiatry. 1988 ; 45 ( 6 ) : 553 -- 9. doi : 10.1001 / archpsyc. 1988.01800300049005. PMID 3377641. ^ Jump up to : Seeman P, Schwarz J, Chen JF, et al. Psychosis pathways converge via D2high dopamine receptors. Synapse. 2006 ; 60 ( 4 ) : 319 -- 46. doi : 10.1002 / syn. 20303. PMID 16786561. Jump up ^ Safra, JE ( Chairman ) 2005 ' Cooperativity ' The New Encyclopaedia Britannica, Vol 3, Micropaedia, p 666 Jump up ^ Fuxe K, Marcellino D, Guidolin D, Woods A, Agnati L, Chapter 10 -- Dopamine Receptor Oligermization, in Neve KA ( ed ) ' Dopamine Receptors ' Springer ( 2009 ) ^ Jump up to : `` Dopamine Receptors : Clinical Correlates ''. Acnp.org. Retrieved 2015 - 05 - 26. Jump up ^ Seeman, P. ; Guan, H.C. ; Civelli, O. ; Van Tol, H.H.M. ; Sunahara, R.K. ; Niznik, H.B. ( 1992 ). `` The cloned dopamine D2 receptor reveals different densities for dopamine receptor antagonist ligands. Implications for human brain positron emission tomography ''. European Journal of Pharmacology : Molecular Pharmacology. 227 ( 2 ) : 139 -- 146. doi : 10.1016 / 0922 - 4106 ( 92 ) 90121 - B. Jump up ^ Zakzanis KK, Hansen KT. Dopamine D2 densities and the schizophrenic brain. Schizophrenia Research. 1998 ; 32 ( 3 ) : 201 -- 6. doi : 10.1016 / s0920 - 9964 ( 98 ) 00041 - 3. PMID 9720125. Jump up ^ Seeman P, Kapur S. Schizophrenia : more dopamine, more D2 receptors. Proc. Natl. Acad. Sci. U.S.A.. 2000 ; 97 ( 14 ) : 7673 -- 5. doi : 10.1073 / pnas. 97.14. 7673. PMID 10884398. Jump up ^ Abi - Dargham A, Rodenhiser J, Printz D, et al. Increased baseline occupancy of D2 receptors by dopamine in schizophrenia. Proc. Natl. Acad. Sci. U.S.A.. 2000 ; 97 ( 14 ) : 8104 -- 9. doi : 10.1073 / pnas. 97.14. 8104. PMID 10884434. Jump up ^ Vernaleken I, Eickhoff S, Veselinovic T, et al. Elevated D2 / 3 - receptor availability in schizophrenia : A ( 18F ) fallypride study. NeuroImage. 2008 ; 41 : T145. doi : 10.1016 / j. neuroimage. 2008.04. 113. Jump up ^ Cropley VL, Innis RB, Nathan PJ, et al. Small effect of dopamine release and no effect of dopamine depletion on 18Ffallypride binding in healthy humans... Synapse. 2008 ; 62 ( 6 ) : 399 -- 408. doi : 10.1002 / syn. 20506. PMID 18361438. Jump up ^ Abi - Dargham A, Elsmarieke E, Slifstein M, Kegeles LS, Laruelle M. Baseline and Amphetamine - Stimulated Dopamine Activity Are Related in Drug - Naïve Schizophrenic Subjects. Biological Psychiatry. 2009 ; 65 ( 12 ) : 1091 -- 3. doi : 10.1016 / j. biopsych. 2008.12. 007. PMID 19167701. Jump up ^ `` Amphetamine psychosis has been proposed as a model for some features of schizophrenia... This model of amphetamine sensitization has also been adopted as a paradigm for researchers interested in the addictive powers of drugs of abuse. '' Jump up ^ Bradley KC, Meisel RL. Sexual Behavior Induction of c - Fos in the Nucleus Accumbens and Amphetamine - Stimulated Locomotor Activity Are Sensitized by Previous Sexual Experience in Female Syrian Hamsters. J. Neurosci... 2001 ; 21 ( 6 ) : 2123 -- 30. PMID 11245696. Jump up ^ Wong DF, Wagner H, Tune L, et al. Positron emission tomography reveals elevated D2 dopamine receptors in drug - naive schizophrenics. Science. 1986 ; 234 ( 4783 ) : 1558 -- 63. doi : 10.1126 / science. 2878495. PMID 2878495. Jump up ^ Abi - Dargham A, Moore H. Prefrontal DA transmission at D receptors and the pathology of schizophrenia. Neuroscientist. 2003 ; 9 ( 5 ) : 404 -- 16. doi : 10.1177 / 1073858403252674. PMID 14580124. Jump up ^ Seeman P, Guan H-C, Van Tol HH. Dopamine D4 receptors elevated in schizophrenia. Nature. 1993 ; 365 ( 6445 ) : 441. doi : 10.1038 / 365441a0. PMID 8413587. Jump up ^ For a discussion of opposing studies see p 143 : Seeman P, Guan H-C, Nobrega J et al. Synapse. 1997 ; 25 ( 2 ) : 137 -- 46. doi : 10.1002 / ( SICI ) 1098 - 2396 ( 199702 ) 25 : 2 < 137 : : AID - SYN4 > 3.0.CO ; 2 - D. PMID 9021894. Jump up ^ Levitzki A, Schlessinger J. Cooperativity in associating proteins. Monomer - dimer equilibrium coupled to ligand binding. Biochemistry. 1974 ; 13 ( 25 ) : 5214 -- 9. doi : 10.1021 / bi00722a026. PMID 4433518. Jump up ^ Seeman P. All Psychotic Roads Lead to Increased Dopamine D2High Receptors : A Perspective. Clinical Schizophrenia & Related Psychoses. 2008 ; 1 : 351 -- 5. doi : 10.3371 / CSRP. 1.4. 7. Jump up ^ Seeman P, Van Tol HH. Dopamine receptor pharmacology... Trends in Pharmacological Sciences. 1994 ; 15 ( 7 ) : 264 -- 70. doi : 10.1016 / 0165 - 6147 ( 94 ) 90323 - 9. PMID 7940991. Jump up ^ R. Thompson, The Brain, ISBN 0 - 7167 - 1462 - 0 Jump up ^ Diaz, Jaime. How Drugs Influence Behavior. Englewood Cliffs : Prentice Hall, 1996. Jump up ^ Richtand, M. ; Welge, A. ; Logue, D. ; Keck Pe, R. ; Strakowski, M. ; Mcnamara, K. ( Aug 2007 ). `` Dopamine and serotonin receptor binding and antipsychotic efficacy ''. Neuropsychopharmacology ( Free full text ). 32 ( 8 ) : 1715 -- 1726. doi : 10.1038 / sj. npp. 1301305. ISSN 0893 - 133X. PMID 17251913. Jump up ^ Williams J, Spurlock G, McGuffin P, Mallet J, Nöthen MM, Gill M, Aschauer H, et al. ( 1996 ). `` Association between schizophrenia and T102C polymorphism of the 5 - hydroxytryptamine type 2a - receptor gene. European Multicentre Association Study of Schizophrenia ( EMASS ) Group ''. The Lancet. 347 : 1294 -- 6. doi : 10.1016 / s0140 - 6736 ( 96 ) 90939 - 3. PMID 8622505. Jump up ^ Berg KA Harvey JA Spampinato U Clarke WP ( 2005 ). `` Physiological relevance of constitutive activity of 5 - HT2A and 5 - HT2C receptors ''. Trends in Pharmacological Sciences. 26 ( 12 ) : 625 -- 630. doi : 10.1016 / j. tips. 2005.10. 008. PMID 16269190. Jump up ^ `` Daring to Think Differently about Schizophrenia ''. New York Times, February 24, 2008. Jump up ^ Mohn, Amy ; Gainetdinov Caron Koller ( 20 August 1999 ). `` Mice with reduced NMDA receptor expression display behaviors related to schizophrenia ''. Cell. 98 ( 4 ) : 427 -- 436. doi : 10.1016 / S0092 - 8674 ( 00 ) 81972 - 8. Retrieved 30 November 2013. Jump up ^ Verma, Anita ; Moghaddam ( 1 January 1996 ). `` NMDA receptor antagonists impair prefrontal cortex function as assessed via spatial delayed alternation performance in rats : Modulation by dopamine ''. Journal of Neuroscience. 16 ( 1 ) : 373 -- 379. Retrieved 30 November 2013. Jump up ^ Javitt, Daniel ( 2007 ). `` Glutamate and schizophrenia : Phencyclidine, N - methyl - D - aspartate receptors, and dopamine - glutamate interactions ''. International Review of Neurobiology. 78 : 69 -- +. doi : 10.1016 / S0074 - 7742 ( 06 ) 78003 - 5. Retrieved 2 December 2013. Jump up ^ Dalack, Gregory ; Healy Meador - Woodruf ( November 1998 ). `` Nicotine dependence in schizophrenia : Clinical phenomena and laboratory findings ''. American Journal of Psychiatry. 155 ( 11 ) : 1490 -- 1501. doi : 10.1176 / ajp. 155.11. 1490. PMID 9812108. Retrieved 30 November 2013. Jump up ^ Lambe, Evelyn ; Picciotto Aghajanian ( February 2003 ). `` Nicotine induces glutamate release from thalamocortical terminals in pr ''. Neuropsychopharmacology. 28 ( 2 ) : 216 -- 225. doi : 10.1038 / sj. npp. 1300032. Retrieved 30 November 2013. Jump up ^ Zhou, Fu - Ming ; Liang Dani ( December 2001 ). `` Endogenous nicotinic cholinergic activity regulates dopamine release in the striatum ''. Nature Neuroscience. 4 ( 12 ) : 1224 -- 1229. doi : 10.1038 / nn769. PMID 11713470. Retrieved 29 November 2013. Jump up ^ `` Psychiatry 's New Brain - Mind and the Legend of the Chemical Imbalance '' by Ronald W. Pies, MD. July 11, 2011. External links cnsspectrums.com Illustrated description. The Dopamine Hypothesis of Schizophrenia - Anissa Abi - Dargham. Schizophrenia Research Forum. Dopamine and Schizophrenia - Philip Seeman, Scholarpedia. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Dopamine_hypothesis_of_schizophrenia&oldid=815956437 '' Categories : Neuroscience of schizophrenia Hidden categories : Articles needing additional references from August 2009 All articles needing additional references All articles with unsourced statements Articles with unsourced statements from May 2009 Talk Contents About Wikipedia Deutsch Français Polski Edit links This page was last edited on 18 December 2017, at 08 : 56. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: what schizophrenic symptoms are decreased by drugs that selectively block the d2 dopamine receptor
Answer: psychotic