Chemotherapy with dexamethasone, high-dose cytarabine, and cisplatin for parenchymal brain lymphoma.

Ten patients with parenchymal CNS lymphoma received combination chemotherapy with dexamethasone, high-dose cytarabine, and cisplatin (DHAP), and additional therapy according to clinical circumstances. Two of four patients with primary CNS lymphoma achieved and remain in complete remission (CR). Four of six patients with CNS lymphoma at relapse also achieved CR. DHAP is active against CNS lymphoma. Further trials with DHAP, particularly in conjunction with other treatment modalities, are warranted.

Comparison of 1-O-alkyl-, 1-O-alk-1'-enyl-, and 1-O-acyl-2-acetyl-sn-glycero-3-phosphoethanolamines and -3-phosphocholines as agonists of the platelet-activating factor family.

Four naturally occurring platelet-activating factor (PAF) analogs, 1-alk-1'-enyl-2-acetyl-sn-glycero-3-phosphocholine, 1-hexadecanoyl-2-acetyl-sn-glycero-3-phosphocholine, 1-octadecanoyl-2-acetyl-sn-glycero-3-phosphocholine, and 1-alkyl-2-acetyl-sn-glycero-3-phosphoethanolamine, stimulated human neutrophils (PMN) to mobilize Ca2+, degranulate, and produce superoxide anion. They were, respectively, 5-, 300-, 500-, and 4000-fold weaker than PAF in each assay; inhibited PMN-binding of [3H]PAF at concentrations paralleling their biological potencies; and showed sensitivity to the inhibitory effects of PAF antagonists. PAF and the analogs, moreover, desensitized PMN responses to each other but not to leukotriene B4 and actually increased (or primed) PMN responses to N-formyl-MET-LEU-PHE. Finally, 5-hydroxyeicosatetraenoate-enhanced PMN responses to PAF and the analogs without enhancing the actions of other stimuli. It stereospecifically raised each analog's potency by as much as 100-fold and converted a fifth natural analog, 1-alk-1'-enyl-2-acetyl-sn-glycero-3-phosphoethanolamine from inactive to a weak stimulator of PMN. PAF and its analogs thus represent a structurally diverse family of cell-derived phospholipids which can activate, prime, and desensitize neutrophils by using a common, apparently PAF receptor-dependent mechanism.

Prognostic factors in advanced ovarian carcinoma.

Nineteen factors were analyzed for prognostic significance in a series of 89 women with advanced (stage III or IV) ovarian carcinoma treated with chemotherapy after initial debulking surgery. Seventy-eight of these women received cyclophosphamide, Adriamycin (Adria Laboratories, Columbus, Ohio), and cisplatin (CAP) treatment, and 11 received cyclophosphamide initially with Adriamycin and cisplatin administered at the time of recurrence. Median survival and remission duration were 25 and 19 months, respectively. Using survival as an end point, significant prognostic factors in univariate analyses included the total residual mass after debulking (P = .0007), largest residual mass after debulking (P = .0008), and stage (P = .0098). Using remission duration as an end point, significant prognostic factors in univariate analyses included total residual mass after debulking (P = .007) and the largest residual mass after debulking (P = .0020). The prognostic variables were then considered as possible predictors of survival in a multivariate analysis using the Cox proportional hazards model resulting in the following expression: lambda i(t)/lambda o(t) = exp(0.5928 (log TRM - 1.8117) + 0.6450 (stage - 0.3827) + 0.6673 (C4 - 0.4198) - 0.8596 (CAP - 0.8642)), where lambda i(t)/lambda o(t) is the risk of dying for a particular patient compared with the average risk of the entire group; log TRM is the log of the volume of the total residual mass in cm3 plus 1.0; stage = 0 if stage III, 1 if stage IV; C4 = 0 if cytologic grade is 1, 2, or 3 and 1 if grade 4; CAP = 0 if treatment is cyclophosphamide and 1 if CAP. Median survival times of patients with relative risk greater than 1 and less than 1 are 43 and 19 months respectively. If this model is confirmed in a prospective study, then it could be used to assign risk and assess treatment options for similar patients at diagnosis.

A new serologic staging system for large-cell lymphomas based on initial beta 2-microglobulin and lactate dehydrogenase levels.

We report results of our investigation of prognostic factors for patients with large-cell lymphoma who were entered on the same treatment protocol and who had known pretreatment serum beta 2-microglobulin (beta 2M) and lactate dehydrogenase (LDH) levels. beta 2M and LDH levels were the most significant and independent variables for predicting time to treatment failure (TTF) and survival. The serum level of beta 2M correlated with tumor burden. These two serum markers defined three significantly different prognostic groups. All 27 patients in the low-risk group remain alive and in remission; in contrast, 22 of the 27 patients (81%) in the high-risk group have failed treatment, and only seven (26%) remain alive. In comparison with the Ann Arbor staging system, serum levels of beta 2M and LDH may provide a more precise system for defining risk groups and thereby allow a more rational approach to the development and analysis of treatment strategies.

Leukemia following treatment of germ cell tumors in men.

We investigated the incidence of leukemia occurring subsequent to the treatment of germ cell tumors in men at our institution over a 30-year interval and found four patients with acute nonlymphocytic leukemia (ANLL) and one patient with chronic myelomonocytic leukemia. The relative risk (observed/expected cases) estimates for the development of leukemia ranged from 13.7 (P = .0005) in the total population to 50.1 (P = .0001) in the group treated with cytotoxic agents alone. All three patients with ANLL treated with contemporary antileukemic therapy had complete responses, with survivals of 7, 29, and 133 + months. In a review of the literature, 14 additional cases of germ cell tumors were found in which the men subsequently developed leukemia. It is concluded that leukemia following germ cell tumors is increased in incidence and is likely to be treatment induced. Complete responses and long-term survival are possible in secondary leukemia and aggressive antileukemic therapy should be given.

Phase II trial of fludarabine phosphate in lymphoma: an effective new agent in low-grade lymphoma.

PURPOSE: In a phase II trial we investigated fludarabine phosphate (FAMP) as therapy for patients with relapsed lymphoma to determine its effectiveness and toxicity in this disease. PATIENTS AND METHODS: The 67 assessable patients had a median age of 56 years and had received a median of three chemotherapy regimens before treatment with FAMP. The starting dose was 25 mg/m2 administered intravenously over 30 minutes daily for 5 days every 3 to 4 weeks. RESULTS: High response rates were observed for follicular small cleaved-cell lymphoma (FSCCL) (62%), follicular mixed small- and large-cell lymphoma (80%), and follicular large-cell lymphoma (FLCL) (100%). Responses also occurred in small lymphocytic lymphoma (SLL) (33%), transformed lymphoma (33%), mycosis fungoides (40%), and Hodgkin's disease (25%). No responses were observed in other intermediate- or high-grade lymphomas (N = 20). Overall, there were five patients with a complete response, 23 patients with a partial response, and an overall response rate of 37%. Toxicity was primarily hematologic and infectious. No significant gastrointestinal, hepatic, renal, or neurologic toxicity occurred. CONCLUSIONS: We conclude that FAMP has major activity in follicular lymphoma. Fundamental research is needed to understand this differential efficacy in low-grade lymphoma yet lack of efficacy in intermediate- and high-grade lymphoma. Clinical investigations should be done using FAMP in varying dose schedules and in combination regimens.

Phase I study of the combination of fludarabine, mitoxantrone, and dexamethasone in low-grade lymphoma.

PURPOSE: Fludarabine is an active agent for patients with low-grade lymphoma (LGL) but has mainly been used as a single agent. This trial was designed to define the maximum-tolerated dose (MTD) of a combination of fludarabine, mitoxantrone, and dexamethasone (FND), to identify the toxicities of these agents in combination, and to make preliminary observations about the efficacy of this combination. PATIENTS AND METHODS: Twenty-one patients with recurrent LGL or follicular large-cell lymphoma were treated, in cohorts of three, at stepwise escalating doses. Patients were required to have adequate marrow function and normal renal, hepatic, and cardiac function. RESULTS: The MTD of the combination was found to be as follows: fludarabine, 25 mg/m2/d (days 1 to 3); mitoxantrone, 10 mg/m2 (day 1); and dexamethasone, 20 mg/d (days 1 to 5). Each course was administered monthly, and up to eight courses were given. Dose-limiting toxicities were neutropenia and infections. Thrombocytopenia was modest. Nonhematologic toxicity was very modest. Responses were seen at every dose level. The overall response rate was 71%, with a 43% complete remission (CR) rate. The median duration of CR was 18 months (with follow-up duration from 13 to 28+ months). CONCLUSION: FND was well tolerated in this population. While our primary aim was to define the MTD, our preliminary observations on the efficacy of the regimen were favorable. The overall response rate was high, there was a high fraction of CRs, and our early impression is that these responses are durable.

Small noncleaved cell lymphoma in adults: superior results for stages I-III disease.

Small noncleaved cell lymphoma (SNCCL), a rare lymphoma in adults, is associated with not only a rapid complete response (CR) to chemotherapy but also with the potential to rapidly relapse both systemically and in the CNS. We treated 44 assessable adults with two similar protocols, consisting of three sequential chemotherapy combinations and intrathecal prophylaxis with methotrexate and cytarabine. The overall CR rate was 80%; it was 100% in patients with Ann Arbor (AA) stages I-III disease and 57% in those with stage IV disease. The overall survival (OS) rate at 5 years was 52%. The overall 5-year freedom from tumor mortality (FTM) rate was 63%; it was 95% for patients with AA stages I-III disease, and 29% for those with stage IV disease. Stepwise multivariate analysis of factors associated with remission duration and survival indicated that advanced-disease stage and age of 40 years or over were predictors of poor prognosis. Twelve patients with positive human immunodeficiency virus (HIV) serology were also included in this series. They had an 83% CR rate and an 83% 5-year FTM, but only a 36% 5-year OS; most deaths were secondary to opportunistic infection. Histologic subtype (Burkitt's lymphoma [BL] or non-Burkitt's lymphoma [NBL]) did not correlate with patient age, site of tumor presentation, response to therapy, or survival. Both protocols achieved comparable results. The approach used in these protocols is highly effective for patients with early staged disease, regardless of their HIV status; however, better therapy is necessary for those with SNCCL presenting in an advanced stage.

Semen cryopreservation and artificial insemination for Hodgkin's disease.

Seventy-nine men with Hodgkin's disease were treated with chemotherapy protocols at Memorial Sloan-Kettering Cancer Center and had pretreatment semen analysis performed at the area semen bank. The patients were evaluated to determine: the quality of pretreatment semen, the effect of treatment on spermatogenesis, and the success rate of artificial insemination after semen cryopreservation. Pretreatment sperm concentration, fresh motility, fresh progression, postthaw motility and postthaw progression were all significantly decreased in men with Hodgkin's disease compared with normal controls. Posttreatment semen analysis in 44 men showed azoospermia in 80%, sperm concentration, less than or equal to 10 X 10(6)/mL in 11%, and sperm concentration greater than 10 X 10(6)/mL in 9%. Eleven couples attempted artificial insemination using cryopreserved semen, thus far resulting in three pregnancies. Semen cryopreservation and artificial insemination offer a partial solution to posttreatment azoospermia in this population, but further methods are needed to minimize gonadal toxicity without compromising therapy for Hodgkin's disease.

Discordant bone marrow involvement in diffuse large-cell lymphoma: a distinct clinical-pathologic entity associated with a continuous risk of relapse.

From 1975 to 1988, 50 patients with lymph node biopsy-documented diffuse large-cell lymphoma (DLCL) presented with bone marrow involvement. Twenty-four patients (48%) had large-cell lymphoma (LCL) in the bone marrow and were compared with 19 (38%) patients who had small cleaved-cell lymphoma (SCCL) in the marrow. Additionally, seven patients (14%) had mixed small- and large-cell lymphoma (ML) in the marrow. Patients who had LCL marrow involvement were younger (P less than .02) and more frequently had elevated lactic dehydrogenase (LDH) levels (P less than .001), high tumor burden (P less than .01), and more sites of extranodal disease (P less than .05) than those with SCCL in the marrow. The complete response (CR) rate to multiagent chemotherapy was 16.7% in the LCL group and 89.4% in the SCCL group (P less than .001). One third of the patients with LCL in the marrow developed CNS involvement, compared with only one patient in the SCCL group (P = .06). Overall 5-year survival was 79% in patients with SCCL marrow involvement, compared with only 12% in patients with LCL in the marrow (P = .002). Despite a high CR rate, patients with marrow involved by SCCL were at a high continuous risk of relapse with only a 30% failure-free survival at 5 years. We conclude that bone marrow involvement with LCL predicts for extremely poor prognosis with low response rate and short survival. Patients with SCCL in the bone marrow have a high rate of CR and a high rate of 5-year survival; however, there is a high risk of late relapse, and only 15% are in a continuous remission at 8 years.

The effect of traumatic brain injury on the timing of sleep.

While there have been single case reports of the development of circadian rhythm sleep disorders, most commonly delayed sleep phase syndrome following traumatic brain injury (TBI), to our knowledge there have been no group investigations of changes to sleep timing in this population. The aim of the present study was to investigate sleep timing following TBI using the dim light melatonin onset (DLMO) as a marker of circadian phase and the Morningness-Eveningness Questionnaire (MEQ) as a measure of sleep-wake behavior. A sleep-wake diary was also completed. It was hypothesized that the timing of DLMO would be delayed and that there would be a greater tendency toward eveningness on the MEQ in a post-acute TBI group (n=10) compared to a gender and age matched control group. Participants were recruited at routine outpatient review appointments (TBI) and from the general population (control) as part of a larger study. They attended the sleep laboratory where questionnaires were completed, some retrospectively, and saliva melatonin samples were collected half-hourly according to a standard protocol. The results show that the TBI and control groups reported similar habitual sleep times and this was reflected on the MEQ. There was, however, significant variability in the TBI group's change from the pre-injury to the current MEQ score. The timing of melatonin onset was not different between the groups. While subtle changes (advances or delays) in this small sample may have cancelled each other out,. the present study does not provide conclusive objective evidence of shift in circadian timing of sleep following TBI. Furthermore, although participants did report sleep timing changes, it is concluded that the MEQ may not be suitable for use with this cognitively impaired clinical group.

Circadian entrainment and phase shifting in mammals with melatonin.

Circadian effects of exogenous melatonin, whereby daily administration induces entrainment or phase shifts, have been demonstrated in both nocturnal and diurnal mammals. In Long-Evans rats, as used in early studies, effects occur reliably when melatonin is administered late in the subjective day. A second period of sensitivity to melatonin, late in the subjective night, is evident in certain strains of mice and the diurnal Funambulus pennanti. This late night to early morning sensitive phase previously had been identified in human subjects. Different circadian responses to melatonin also may occur between rat strains. Circadian effects of melatonin in hamsters are diverse and vary with strain, developmental age, and method of administration. Characteristics of melatonin binding sites within the suprachiasmatic nuclei vary both between and within species, as do profiles of endogenous melatonin rhythms. These differences may explain the variations in circadian responses to melatonin.

Effects of daily melatonin administration on circadian activity rhythms in the diurnal Indian palm squirrel (Funambulus pennanti).

Exogenous melatonin induces phase shifts in circadian rhythms according to a phase response curve in nocturnal rodents, several nonmammalian diurnal species, and humans. Daily administration of melatonin entrains rhythms within a narrow circadian window of sensitivity in these species. Entrainment to exogenous melatonin has not previously been demonstrated in a (nonhuman) diurnal mammal. The authors examined the effects of daily melatonin administration (via food) in the diurnal Indian palm squirrel, Funambulus pennanti. The effects of melatonin or vehicle were examined at two times of day: zeitgeber time 0 (ZT 0: light onset time) and ZT 12 (dark onset time). In addition to melatonin- and vehicle-treated squirrels, there was a third group of squirrels that received no treatment. Squirrels were held initially under 12:12 light-dark (LD) cycles, and melatonin (1 mg/kg) or vehicle was administered in food (a raisin) at either ZT 0 or ZT 12 for a total of 17 days. On the third day of treatment, constant lighting (LL) was imposed. Treatment continued at the same ZTs for a further 14 days. The number of days before free-running commenced under constant conditions was assessed for squirrels in each treatment group. Results showed that regardless of the ZT of administration, the number of days before free-running commenced was significantly greater in melatonin-treated squirrels than in vehicle-treated and untreated squirrels, and there was no difference between vehicle-treated and untreated squirrels. Although there was not a significant difference in the number of days before free-running commenced between the two times of administration, the results showed a trend for greater sensitivity to melatonin at ZT 12. This study has therefore demonstrated that the palm squirrel circadian system is entrainable to melatonin at both times of day tested, ZTs 0 and 12. This finding is in contrast to previous melatonin entrainment studies in other species, where entrainment generally occurred at only one phase, around circadian times 10 to 12. Interspecies differences in response to melatonin were discussed.

Entrainment of rat circadian rhythms by the melatonin agonist S-20098 requires intact suprachiasmatic nuclei but not the pineal.

S-20098 is a potent nonindolic melatonin agonist that has been shown to entrain free-running circadian rhythms. The current experiments examined the role of the suprachiasmatic nuclei (SCN) and of the pineal gland in the entrainment of circadian rhythms by S-20098. First, daily injections of S-20098 (1 and 10 mg/kg s.c.) were administered to SCN- and sham-lesioned rats. At both dose levels, circadian effects were noted in all sham-lesioned animals. Locomotor activity and body temperature rhythms in 3 of 5 sham-lesioned rats were entrained by the daily injections. In SCN-lesioned rats, S-20098 had no synchronizing or entraining effects at either dose level. These results show that S-20098 exerts its entraining effects on circadian rhythms via the circadian pacemaker located in the SCN. Second, the effects of daily injections of S-20098 (10 mg/kg s.c.) were examined in pinealectomized, sham-pinealectomized, and intact rats. All rats receiving S-20098, irrespective of surgical treatment, showed circadian changes. Rhythms in 81% of these animals entrained to daily administration of the compound, indicating that entrainment induced by S-20098 does not depend on an intact pineal. When injected with 10 mg/kg S-20098, 69% of rats, irrespective of surgical treatment, showed long-term modifications of free-running period that still were evident several weeks after administration ceased. If confirmed, this finding may have therapeutic implications in humans regarding the optimal mode and administration of S-20098 in a clinical setting.

Results of recent salvage chemotherapy regimens for lymphoma and Hodgkin's disease.

From 1981 to 1983, 208 patients with recurrent or refractory lymphoma were treated with methylglyoxal-bis-guanylhydrazone (methyl-GAG), ifosfamide, methotrexate, etoposide (MIME). The complete remission (CR) rate was 24% and CR plus partial remission (PR) was 60%. Response was higher for aggressive than for indolent cell types. Median duration of CRs was 16.5 months and median survival of all patients was 9 months. In view of the in vitro synergism between cisplatin and high-dose cytarabine, we recently designed the DHAP regimen, which consists of cisplatin, 100 mg/m2 IV over 24 hours; cytarabine, 2 g/m2 IV over two hours every 12 hours for two doses; and dexamethasone, 40 mg orally daily for 4 days. There were 28 of 90 (31%) CRs and 22 of 90 (24%) PRs. Median duration of CR is 15 months; median survival of all patients is 6 months. The major toxicities have been infection (31%) and moderate to severe renal dysfunction (20%). In contrast to MIME, response rates did not differ significantly between aggressive and indolent cell types. A high-dose regimen (CBV) consisting of cyclophosphamide, 6 g/m2; carmustine, 300 mg/m2; and etoposide, 250 mg/m2 daily for 3 days followed by autologous bone marrow transplant (ABMT) has been successfully used to treat 62 patients with Hodgkin's disease recurrent or refractory after mechlorethamine, vincristine, procarbazine, prednisone, doxorubicin, bleomycin, vinblastine, dacarbazine (MOPP/ABVD)-like regimens. A CR rate (47%) has been observed; 83% of these CRs remain alive and free of disease with a median follow-up of 19 months. This regimen appears to have curative potential in 40% of all cases and in 60% of cases treated after the first or second relapse.(ABSTRACT TRUNCATED AT 250 WORDS)

Fludarabine phosphate therapy in other lymphoid malignancies.

The promising results obtained with Fludara I.V. (fludarabine phosphate) treatment in the common indolent B-cell neoplasms have led to their further evaluation in other unusual B-cell malignancies, in Hodgkin's disease, and in T-cell diseases. A significant response rate has been found among patients with macroglobulinemic lymphoma, those with prolymphocytic leukemia or prolymphocytoid variant of chronic lymphocytic leukemia, and those with mycosis fungoides. The limited therapeutic data in hairy-cell leukemia and in Hodgkin's disease are also interesting.

NOVP: a novel chemotherapeutic regimen with minimal toxicity for treatment of Hodgkin's disease.

Patients with early-staged Hodgkin's disease have had a higher relapse rate following radiotherapy alone if they have B symptoms, large mediastinal masses, hilar involvement, or stage III disease. From June 1988 to December 1989, 27 previously untreated patients with early-staged Hodgkin's disease with adverse features for disease-free survival received combined-modality therapy. Seventeen patients had stage I or II disease, 10 had stage III, 5 had B symptoms, 13 had large mediastinal masses, and 6 had peripheral masses measuring 10 cm or more in diameter. All patients initially received three cycles of a novel chemotherapeutic regimen combining Novantrone (mitoxantrone, American Cyanamid Company), vincristine, vinblastine, and prednisone (NOVP). Twenty-four patients with clinically staged I or II disease with adverse features or stage III disease did not undergo laparotomy; three patients had favorable stage I or II disease and at laparotomy had stage III disease. Radiotherapy-treatment fields depended on the extent of nodal involvement. Twenty-six patients completed all therapy as planned to complete remission (CR) and one of these has had progression; she is in second CR following additional radiotherapy. With a median follow-up of 12 months, all patients are alive. Tolerance to treatment was excellent with only grade 1 or 2 nausea, alopecia and myalgias, and brief myelosuppression. NOVP is an effective adjuvant chemotherapy regimen for inducing responses, with minimal toxicity, prior to definitive radiotherapy for patients with early-staged Hodgkin's disease.

Bone mineralization in women following successful treatment of Hodgkin's disease.

PURPOSE: Women with Hodgkin's disease in whom a cure has been achieved may be at risk for osteoporosis because of therapy-induced premature menopause. Our objective was to gather information regarding the integrity of bone mass in such long-term cancer survivors. SUBJECTS AND METHODS: Bone mineral density was measured using photon absorptiometry in five groups of women: 11 patients with Hodgkin's disease and ovarian failure (Group I); six patients with Hodgkin's disease and ovarian failure who received estrogen replacement (Group II); 15 patients with Hodgkin's disease and normal ovarian function (Group III); 16 premenopausal control subjects (Group IV); and 11 postmenopausal control subjects (Group V). All patients with Hodgkin's disease were in remission and had completed treatment more than five years earlier. RESULTS: Subjects in Group I were found to have significantly decreased radial (p = 0.0009), lumbar spine (p = 0.002), and femoral neck (p = 0.0001) bone mineral density measurements compared with those in subjects in Group IV; the bone mineral density measurements at all sites of subjects in Group I were no different than those of subjects in Group V. Subjects in Group III had bone density measurements that were similar to those in Group IV, although the radial bone mineral density value was significantly lower (p = 0.0004). Determination of serum gonadotropins and estradiol was consistent with the menstrual status defining the five groups. No secondary causes for decreased bone mineral density values could be detected, since the mean serum levels of parathyroid hormone, calcium, phosphorus, and vitamin D metabolites were similar among the groups, and all prolactin levels were normal. CONCLUSION: We have identified a new population of patients with a high risk of osteoporosis, and these results emphasize the importance of treatment-related ovarian failure in the pathogenesis of osteoporosis.

Interactive effects of sleep deprivation, time of day, and driving experience on a driving task.

Performance decrements after more than 24 hours of sleep deprivation (SD) are not only a monotonic function of the duration of SD, but are the result of an interaction between SD and time of day. The major deteriorations in performance during SD are still evident throughout the night, as in the non-sleep-deprived state. Twelve experienced and 12 inexperienced drivers drove a driving simulator for 20 minutes at 0800, 1100, 1400, 1700, and 2000 hours on two testing days. One testing day was conducted after a normal night's sleep, and the other after one night of SD. Reaction time (RT) was also measured while driving. The standard deviation of both lateral position and speed were significantly higher during SD. Performance steadily improved across the day between 0800 and 2000 hours, and the absence of any sleep-by-time interactions suggests that the rhythm of driving performance across the day was similar after both normal sleep and SD. Inexperienced drivers had higher RTs than experienced drivers in both sleep-deprived and non-sleep-deprived conditions. These results have important implications for those involved in the transport industry.

Effects of caffeine, time of day and user history on study-related performance.

The individual and interactive effects of caffeine, time of day and history of caffeine consumption on several study-related tasks were investigated in 25 subjects (6 males, 19 females). Performance was measured on short term memory (STM), mental arithmetic (MA), reading comprehension, serial search (SS) and verbal reasoning (VR). Subjects attended eight experimental sessions, at four times of day (0100, 0700, 1300 and 1900 hours), after ingesting caffeine (4 mg/kg) or placebo. Subjects were assigned to a low, moderate or high user group on the basis of a caffeine consumption questionnaire. Reading comprehension was affected by time of day, while caffeine improved performance on all mental speed-related tasks. High caffeine users performed more poorly than other groups on the verbal reasoning task. Several interactions between the three independent variables were observed on a number of tasks, supporting the contention that different processes underlying various types of cognitive performance are differentially, and often jointly, affected by caffeine, time of day and user history. Implications of caffeine usage on academic performance were discussed.