Shared vulnerability between seizures and psychosis in cocaine addiction?

Ca2+ channel blockade reduces cocaine's vasoconstriction and neurotoxicity in the prefrontal cortex

Cocaine profoundly affects both cerebral blood vessels and neuronal activity in the brain. The vasoconstrictive effects of cocaine, concurrently with its effects on neuronal [Ca²⁺]_i accumulation are likely to jeopardize neuronal tissue that in the prefrontal cortex (PFC) could contribute to impaired self-regulation and compulsive cocaine consumption. Here we used optical imaging to study the cerebrovascular and neuronal effects of acute cocaine (1 mg/kg i.v.) and to examine whether selective blockade of L-type Ca²⁺ channels by Nifedipine (NIF) (0.5 mg/kg i.v.) would alleviate cocaine's effects on hemodynamics (measured with cerebral blood volume, HbT), oxygenation (measured with oxygenated hemoglobin, HbO₂) and neuronal [Ca²⁺]_i, which were concomitantly measured in the PFC of naive rats. Our results show that in the PFC acute cocaine significantly reduced flow delivery (HbT), increased neuronal [Ca²⁺]_i accumulation and profoundly reduced tissue oxygenation (HbO₂) and these effects were significantly attenuated by NIF pretreatment. They also show that cocaine-induced vasoconstriction is distinct from its increase of neuronal [Ca²⁺]_i accumulation though both of them contribute to hypoxemia and both effects were attenuated by NIF. These results provide evidence that blockade of voltage-gated L-type Ca²⁺ channels might be beneficial in preventing vasoconstriction and neurotoxic effects of cocaine and give support for further clinical investigations to determine their value in reducing cocaine's neurotoxicity in cocaine use disorders.

Short-term withdrawal from repeated exposure to cocaine during adolescence modulates dynorphin mRNA levels and BDNF signaling in the rat nucleus accumbens

BACKGROUND

Early-life stressful events affect the neurobiological maturation of cerebral circuitries including the endogenous opioid system and the effects elicited by adolescent cocaine exposure on this system have been poorly investigated. Here, we evaluated whether cocaine exposure during adolescence causes short- or long-term alterations in mRNAs codifying for selected elements belonging to the opioid system. Moreover, since brain-derived neurotrophic factor (BDNF) may undergo simultaneous alterations with the opioid peptide dynorphin, we also evaluated its signaling pathway as well.

METHODS

Adolescent male rats were exposed to cocaine (20 mg/kg/day) from post-natal day (PND) 28 to PND42, approximately corresponding to human adolescence. After short- (PND45) or long-term (PND90) abstinence, prodynorphin-κ-opioid receptor (pDYN-KOP) and pronociceptin-nociceptin receptor (pN/OFQ-NOP) gene expression were evaluated in the nucleus accumbens (NAc) and hippocampus (Hip) together with the analysis of BDNF signaling pathways.

RESULTS

In the NAc of PND45 rats, pDYN mRNA levels were up-regulated, an effect paralled by increased BDNF signaling. Differently from NAc, pDYN mRNA levels were down-regulated in the Hip of PND45 rats without significant changes of BDNF pathway. At variance from PND45 rats, we did not find any significant alteration of the investigated parameters either in NAc and Hip of PND90 rats.

CONCLUSIONS

Our results indicate that the short-term withdrawal from adolescent cocaine exposure is characterized by a parallel pDYN mRNA and BDNF signaling increase in the NAc. Given the depressive-like state experienced during short abstinence in humans, we hypothesize that such changes may contribute to promote the risk of cocaine abuse escalation and relapse.

Cocaine use as an independent predictor of seizures after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Seizures are relatively common after aneurysmal subarachnoid hemorrhage (aSAH). Seizure prophylaxis is controversial and is often based on risk stratification; middle cerebral artery (MCA) aneurysms, associated intracerebral hemorrhage (ICH), poor neurological grade, increased clot thickness, and cerebral infarction are considered highest risk for seizures. The purpose of this study was to evaluate the impact of recent cocaine use on seizure incidence following aSAH.

METHODS

Prospectively collected data from aSAH patients admitted to 2 institutional neuroscience critical care units between 1991 and 2009 were reviewed. The authors analyzed factors that potentially affected the incidence of seizures, including patient demographic characteristics, poor clinical grade (Hunt and Hess Grade IV or V), medical comorbidities, associated ICH, intraventricular hemorrhage (IVH), hydrocephalus, aneurysm location, surgical clipping and cocaine use. They further studied the impact of these factors on "early" and "late" seizures (defined, respectively, as occurring before and after clipping/coiling).

RESULTS

Of 1134 aSAH patients studied, 182 (16%) had seizures; 81 patients (7.1%) had early and 127 (11.2%) late seizures, with 26 having both. The seizure rate was significantly higher in cocaine users (37 [26%] of 142 patients) than in non-cocaine users (151 [15.2%] of 992 patients, p = 0.001). Eighteen cocaine-positive patients (12.7%) had early seizures compared with 6.6% of cocaine-negative patients (p = 0.003); 27 cocaine users (19%) had late seizures compared with 10.5% non-cocaine users (p = 0.001). Factors that showed a significant association with increased risk for seizure (early or late) on univariate analysis included younger age (< 40 years) (p = 0.009), poor clinical grade (p = 0.029), associated ICH (p = 0.007), and MCA aneurysm location (p < 0.001); surgical clipping was associated with late seizures (p = 0.004). Following multivariate analysis, age < 40 years (OR 2.04, 95% CI 1.355-3.058, p = 0.001), poor clinical grade (OR 1.62, 95% CI 1.124-2.336, p = 0.01), ICH (OR 1.95, 95% CI 1.164-3.273, p = 0.011), MCA aneurysm location (OR 3.3, 95% CI 2.237-4.854, p < 0.001), and cocaine use (OR 2.06, 95% CI 1.330-3.175, p = 0.001) independently predicted seizures.

CONCLUSIONS

Cocaine use confers a higher seizure risk following aSAH and should be considered during risk stratification for seizure prophylaxis and close neuromonitoring.

A systematic review of evidence on the association between cocaine use and seizures

BACKGROUND

Institutional monographs/medical textbooks mention seizures as a neurological complication of cocaine, but no systematic reviews (SRs) have been published on this issue. We aimed to conduct a SR of the literature on the relationship between cocaine use and seizures and to summarize the biological plausibility of that relationship.

METHODS

The pathophysiological mechanisms that may underlie an association between cocaine and seizures were summarized; a SR was then performed using three databases (EMBASE, Medline, PsycINFO) and the Cochrane-library to search for published papers (1980-2012) aimed at quantifying the associations between cocaine use and seizures. The inclusion criteria for selection were: articles based on clinical trials, cohort, case-control (CC) or cross-sectional (CS) studies, participants ≥ 14 years old and not pregnant, and use of cocaine in the last 72 h. Information was extracted, evaluated and cross-checked independently by two researchers.

RESULTS

Of the 1243 potentially relevant articles initially identified; one CC and 22 CS studies were finally selected. The CC study did not find cocaine use to be a risk-factor for seizures. In addition to the limitations of the CS design, these studies had important methodological weaknesses and biases.

CONCLUSIONS

Despite its biological plausibility, no rigorous scientific evidence supports a causal relationship between cocaine use and seizures. The misinterpretation of the role of cocaine may have important implications in medical services. Well-conducted studies are urgently needed.