The effect of Ginkgo biloba on memory in healthy male volunteers.

The purpose of this study was to investigate possible effects of Ginkgo biloba, a widely used herbal extract, on memory. This study incorporated a double-blind, placebo-controlled design, which used 30 healthy male subjects in each of two groups. The treatment group received two 60-mg tablets of BioGinkgo (27/7) [corrected] daily for 5 days, while the placebo group received a placebo. On the fifth day, after a 2-h waiting period, all subjects were given the Sternberg Memory Scanning Test [Q. J. Exp. Psychol. 27 (1975) 1.], a reaction time control test, the vocabulary and digit span subtests of the WAIS-R [Wechsler D. Manual for the Wechsler adult intelligence scale - revised. New York: Psychological Corporation, 1981.], a reading span test [J. Verbal Learn. Verbal Behav. 19 (1980) 450.] and a prose recall test [Discourse Proc. 13 (1990) 387.]. Blood pressure, heart rate and side effects were also monitored throughout the study. Nonsignificant results were found on all interactions involving treatment group on all tests except the Sternberg Memory Scanning Test. The extract appeared to be safe but largely ineffective in enhancing memory.

Lexical properties of the Boston Naming Test stimuli: age differences in word naming and lexical decision latency.

Two experiments examined the lexical properties of the word representations of the Boston Naming Test (BNT; Kaplan, Goodglass, & Weintraub, 1983) stimuli and whether these properties differentially influenced performance of young and older adults in a speeded word naming task and a lexical decision task. The lexical properties of the word representations examined were familiarity, number of letters, frequency of the word's occurrence, and number of syllables. The results of Experiment 1 indicated that the process of lexical access was similar in young and older adults and provided the first examination of lexical properties of the BNT stimuli in a speeded naming situation. The purpose of Experiment 2 was to reexamine the questions raised in Experiment 1 using a lexical decision task. The results of the analysis in Experiment 2 indicated that age was a significant predictor of performance on the lexical decision task. None of the other predictors contributed significantly to the regression equation.

An analysis of the "eveningness-morningness" dimension in "depressive" college students.

BACKGROUND: Circadian variability in depression has not been well characterized with respect to the "eveningness-morningness" dimension. METHODS: The "eveningness-morningness" dimension, as measured by the Home and Ostberg questionnaire, was examined among a student population (n = 1617) that was named as "depressive". Three depression scales (BDI, GDS-SF, and CESD) were used to determine "depressiveness". The Horne and Ostberg questionnaire was used to measure the degree of "eveningness-morningness". It was hypothesized that there would be negative and significant correlations between the scores on the Horne and Ostberg questionnaire and the depression scales. Consequently, it was expected that there would be a significantly higher number of evening types than the morning types among the participants identified as "depressives". RESULTS: There were significant, negative correlations between the Horne and Ostberg questionnaire scores and the responses on the 3 depression scales (for BDI r= -.174, GDS-SF r= -.182, CESD r = -.176, all p < .001). Also, a significantly higher incidence of evening types than of the morning types among the "depressive" students was found (chi2 = 11.18, p < .01). LIMITATIONS: It is uncertain to what extent these data generalize to clinical populations. CONCLUSIONS: "Depressive" college students are more likely to be evening types.

The role of vocabulary ability during visual word recognition in younger and older adults.

The role that vocabulary ability plays in adult age differences in word recognition was investigated. In Experiment 1, 44 older adults (ages 61-93 years) were compared with 44 younger adults (ages 18-39 years) on a standard lexical-decision task, with ambiguous words, unambiguous words, and pseudowords serving as stimuli. In Experiment 1, the Wechsler Adult Intelligence Scale-Revised (WAIS-R; D. Wechsler, 1981) vocabulary performance was uncontrolled across the younger and older adults, and the older adults had higher WAIS-R scores. There was no Group x Stimulus interaction. In Experiment 2, the data from the same 44 older adults were compared with data from a new sample of 44 younger adults (ages 18-44). Both groups were then matched on WAIS-R performance. Results revealed a significant Group x Stimulus interaction. Reaction time differences between the younger and older groups on the ambiguous words and unambiguous words were identical. The differences in reaction times for words and pseudowords were greater in the older adults. The importance of vocabulary ability during word recognition and lexical processing is discussed.

The effect of moderate levels of simulated altitude on sustained cognitive performance.

Previous work has documented cognitive deficits at high altitudes (15,000-25,000 ft), but there is controversy for lower altitudes. This study looked at the effects of moderate altitudes--12,500 ft and 15,000 ft--on short-term memory in comparison to 2,000 ft. Seventy-two student pilots and instructors were first administered the Vocabulary, Digit Span, and Digit Symbol subtests from the Wechsler Adult Intelligence Scale-Revised, the Vandenberg Mental Rotation Test, and the near-contrast sensitivity portion of the Vistech VCTS 6000 chart. Participants then spent 1 1/2 hr at their designated altitude for cognitive testing. Participants performed a 30 min vigilance task while listening to an audiotape with instructions to recall radio calls prefaced by their assigned call sign. Half of the radio calls were high memory loads (at least 4 pieces of information), and half were low memory loads (no more than 2 pieces of information). No effects of altitude were found in performance on the Vigilance task. However, for readbacks of high memory load, significant deficits in recall were observed at 12,500 ft and 15,000 ft, whereas no effect of altitude was observed on recall of readbacks with low memory loads. These results indicate that, at altitude, short-term memory was exceeded for the readbacks requiring a larger amount of information to be recalled, and that cognitive deficits are found at lower altitudes than previously observed.

Failure of posttrial administration of vasopressin analogue (DDAVP) to influence memory in healthy, young, male volunteers.

The effects of intranasal treatment with DDAVP on healthy, male volunteers was assessed. Subjects were asked to learn prose passages and then were given either 60 micrograms of DDAVP or saline in a double-blind procedure. Subjects were then asked to recall the passages after a 24-h delay. Treatment had no effect on recall of passages. This suggests that treatment with vasopressin affects acquisition rather than consolidation of newly learned information.

Effects of smoking on memory for prose passages.

The present study examined the effects of smoking on memory for prose passages. Habitual male smokers were matched on verbal ability, impulsivity level, and habitual smoking level and were instructed to smoke either a 0.1 mg (control), a 0.7 mg, or a 1.5 mg nicotine cigarette in a controlled fashion. Immediate recall after reading expository passages was obtained. The results indicated that the subjects who smoked the 0.7 mg nicotine cigarette recalled a greater proportion of the idea units than the control group, with no difference between the 1.5 mg group and the control. In addition, blood pressure and heart rate significantly increased in all groups immediately after smoking, with heart rate increases greater in the 0.7 mg and 1.5 mg groups than the control. Interpretive hypotheses for the results include arousal theory, with optimal arousal levels being obtained in the 0.7 mg nicotine group for the prose recall task, and nicotine specific effects, including nicotine's influence on the cholinergic system.

Speed of processing within semantic memory following severe closed head injury.

This study investigated the effects of severe closed head injury (CHI) on the speed of information processing within semantic categories. The question of whether subjects were able to benefit from priming was also investigated. Survivors of severe CHI who were less than 1 year postinjury and survivors who were greater than 1 year postinjury were compared with neurologically normal matched controls utilizing a category judgement task. The results demonstrated slower processing within semantic memory for both groups of CHI patients compared to normal controls. Furthermore, individuals with CHI were able to benefit from priming to the same relative degree as control subjects. Overall, the results suggested semantic organization remains intact after severe CHI, but accessing semantic information is slowed.

Posttrial treatment with ethanol enhances recall of prose narratives.

A small number of studies have examined the effects of postlearning alcohol intoxication on memory for various materials. In contrast to most research examining the effects of alcohol on human memory, these studies demonstrated a facilitation of memory for information learned prior to intoxication. The present study was designed to examine the effects of alcohol on memory for two different kinds of materials. Standard word lists and narrative prose passages were employed to obtain a more detailed picture of the effects of posttrial intoxication with alcohol on memory. Intoxication with alcohol did not affect subject's ability to recall simple word lists. However, recall of prose passages was facilitated to a statistically significant degree. Results are discussed within the context of a current theory of retrograde facilitation of memory via various drugs/substances.

Effects of DDAVP on gender-specific verbal and visuospatial tasks in healthy young adults.

Although several studies have demonstrated the efficacy of the vasopressin analog DDAVP in enhancing human cognition, few previous studies have explored possible interactions of treatment with DDAVP and gender in healthy young adults. The present study was undertaken to explore the effects of treatment with DDAVP on gender-specific tasks. Male and female volunteers were treated with either DDAVP or saline and asked to recall lists of words and to perform the Paper Folding and Stroop Color Word Tests. Although treatment with DDAVP produced few effects in these tasks, the effects that were noted involved impairment of performance.

The recall of prose as a function of importance following closed head injury.

Closed head injury (CHI) results in significant memory dysfunction. Although the disabling aspects of memory impairment after CHI have been recognized, little attention has been focused on the theoretical nature of these memory problems. A means of examining semantic sensitivity to the importance of the ideas presented in the Wechsler Memory Scale-Revised Logical Memory subtest was developed. Subjects with CHI were sensitive to the semantic structure of the stories, but lost more important information at a faster rate than controls. Differences in recall, dependent on the passage, suggested that the two stories in the Wechsler Memory Scale-Revised are not equivalent.

Short-term memory processes following closed head injury.

Survivors of severe closed head injury (CHI) were compared with neurologically normal matched controls on measures of short-term memory processes. The results indicate that patients with CHI took longer to scan their short-term memory than controls, and this increased disproportionately as the memory load increased. The number of errors made in scanning short-term memory increased for patients with CHI, suggesting inefficient as well as slow scanning. These differences were present despite equivalent memory span between groups. The results of this study have implications for day to day memory processes that require manipulation of information in short-term memory.

Gender differences in retrieval from long-term memory following acute intoxication with ethanol.

The present study investigated the effects of ethanol on retrieval from long-term memory by using a set of cognitive decision tasks. Male and female subjects were administered either 0.0 or 1.0 milliliter of ethanol per kilogram of body weight, and then asked to make physical, lexical, and semantic decisions about pairs of words. In general, intoxicated subjects responded significantly slower than sober subjects on all decision types. In addition, female subjects demonstrated greater performance deficits than males when intoxicated. The results suggested that the reduction in speed was not due to a simple slowing of motor responses. Rather the ethanol induced memory deficits may result from the slowing of cognitive operations that impair the efficiency of working memory. Several reasons were proposed for the observed difference in reaction to intoxication between male and female subjects, including neuroendocrine processes and cognitive differences.

Effects of text genre and verbal ability on adult age differences in sensitivity to text structure.

The present study examined the effects of verbal ability and text genre on adult age differences in sensitivity to the semantic structure of prose. Young and older adults of low or high verbal ability heard narrative and expository passages at different presentation rates. The results demonstrated that older adults recalled less than younger adults and that age differences in recall were larger for low-verbal adults and expository texts. However, subjects from all groups favored the main ideas in their recalls for both types of passages. The results indicated that adult age similarities in the ability to focus on the main ideas when processing prose was not compromised by the verbal ability of the subjects or the organization of the passages used. However, the results also demonstrate how the characteristics of the learner and the characteristics of the text modulate the size of the age differences observed.

Vasopressin analogue (DDAVP) facilitates recall of narrative prose.

The effects of treatment with 1-desamino-D-arginine vasopressin (DDAVP) on memory in healthy adult human subjects were investigated. Each subject (males only) received 60 micrograms of DDAVP intranasally and then heard six narrative passages of prose presented at differing rates of presentation. Proportion of recall was measured at high, medium, and low levels of importance of idea units within the passage. The results indicated that treatment with DDAVP facilitated recall for both high and medium importance idea units. There was no interaction between treatment and either rate of presentation or level of verbal ability. These findings provide further evidence for the modest facilitation provided by acute administration of DDAVP on human memory.

The effects of caffeine, impulsivity, and sex on memory for word lists.

The present study examined the effects of caffeine on memory for supraspan word lists. Twelve groups of male and female college students classified as high or low impulsive received either 0, 2, or 4 mg/kg of caffeine. Female subjects were tested only during the menstrual phase of their cycle and were not taking oral contraceptives. Subjects listened to 12 word lists presented at one of four rates. Caffeine facilitated recall in females after practice with the task, but impaired recall in males only at the medium dose. The observed effects of caffeine were not influenced by subject's verbal ability, typical amount of caffeine consumption, or level of impulsivity. The results suggest that the effects of caffeine on females may vary according to the level of estrogen in the subject's system.

Dose-dependent effects of hydrocortisone on memory in human males.

Eighty male undergraduates were administered either glucose or 5, 10, 20, or 40 mg of hydrocortisone in a double-blind procedure. After 60 min they were asked to listen to eight 12 word lists and then asked to recall the words. In addition to the expected effects of rate of presentation, serial position, and practice there was a significant interaction between dose of hydrocortisone and practice. Early recall was facilitated by all doses used whereas later recall was facilitated by treatment with 40 mg and impaired by treatment with 5 mg. These findings are discussed in the context of the effects of pituitary adrenocortical hormones and memory function.

The effects of alcohol on prose memory.

The present study examined the effects of acute alcoholic intoxication on prose memory. Intoxicated and sober subjects listened to six narrative passages at different presentation rates. Immediately after listening to a tape-recorded version of each story, subjects orally recalled it. The results demonstrated that sober subjects recalled more than intoxicated subjects, but subjects from both groups favored the main ideas in their recalls. However, at the fastest presentation rate, intoxicated subjects showed some diminished sensitivity to the semantic structure of prose. It was suggested that alcohol induced deficits in prose memory may result from a general slowing in the rate with which text is encoded into working memory.

Adult age differences in accessing and retrieving information from long-term memory.

The present study employed a series of cognitive decision tasks to investigate adult age differences in accessing and retrieving information from long-term memory. Young and old adults, from low and high education populations, were required to make feature, lexical, and categorical judgments about word pairs. Older adults were slower than younger adults at feature extraction, lexical access, and accessing category information. The age deficit was proportionally greater when retrieval of category information was required. The results suggest that one contribution to the diminished processing capacity in elderly adults may be their slower semantic access speed.