Biomedical subjects

Robert Krikorian

Publications and source records attributed to Robert Krikorian.

6 recordsLinked to original sources

PubMed2005

Exploratory factor analysis of two measures of posttraumatic stress disorder (PTSD) symptoms in a non-clinical sample of college students.

This study investigated the psychometric structure of two widely utilized measures of posttraumatic symptoms in a primarily Caucasian non-clinical sample. Given the prevalence of trauma exposure in non-referred samples, measurement of resulting symptoms is a critical issue. Exploratory factor analysis was utilized to assess and compare the factor structure of the Impact of Event Scale [IES; Horowitz, M., Wilner, N., & Alvarez, W. (1979). Impact of Event Scale: a measure of subjective stress. Psychosomatic Medicine, 41, 209-218] and the Mississippi Scale for Posttraumatic Stress Disorder, Civilian version [MIS-Civ; Vreven, D. L., Gudanowski, D. M., King, L. A., & King, D. W. (1995). The Civilian Version of the Mississippi PTSD Scale-a psychometric evaluation. Journal of Traumatic Stress, 8, 91-109] in a sample of college students reporting exposure to potentially traumatic events. The psychometric structure of the IES was largely consistent with the two-factor structure widely reported in the literature, while the structure of the MIS-Civ varied considerably in this sample. Notably, non-clinical samples tended to report fewer social and occupational dysfunction than clinical samples predominantly utilized in PTSD research. Implications for use of these instruments in screening samples are discussed.

Adult↗

PubMed2005

Working memory and inhibitory control among manic and euthymic patients with bipolar disorder.

Bipolar disorder (BPD) is a severe psychiatric illness that is characterized by episodes of extreme mood states. The affective components of bipolar disorder have been studied extensively, but only recently have investigators begun to systematically examine its cognitive concomitants. Although executive dysfunction has been reported in this population, especially while patients are manic, the tasks administered in many previous studies have made it difficult to determine the specific executive abilities that were compromised. The present study examined 15 patients with bipolar disorder who were manic, 18 who were euthymic, and 18 healthy participants. Tests were selected to evaluate two specific aspects of executive functioning in these participants. The Object Alternation Task was given as a measure of inhibitory control, and the Delayed Response Task was included as a measure of spatial delayed working memory. All groups performed similarly on the Delayed Response Task. On the Object Alternation Task, however, the manic and euthymic patients committed significantly more perseverative errors than healthy participants. These results indicated that patients in the present sample had relatively normal working memory abilities, but had a deficit in behavioral self-regulation, which was evident across mood states.

Adolescent↗

PubMed2005

Corsi Block-Tapping task performance as a function of path configuration.

The Corsi Block-Tapping (CB) task has been used as a measure of spatial memory since its development in 1971. However, a standard set of items has been developed for this task, and inconsistencies in performances within levels have been demonstrated in association with different path configuration. This study investigated item consistency by analyzing the performances of 94 young adult participants on a block-tapping task that involved five quasi-randomly determined sequences at each of nice levels of difficulty. In general, performance declined with increasing path length. Cochran Q-test comparisons were conducted on the items within each level, and differential performance were identified at levels 7 and 8 only. Pairwise comparisons determined the specific items for which performance was discrepant, and further analysis indicated that performance decrement were related to more complicated block-tapping paths. The findings suggest that this version of the CB task is relatively consistent overall, and the observed effect of path configuration indirectly corroborated the spatial nature of this task. Performance heterogeneity at higher levels reflected more complicated path configuration and, presumably, greater span capacity load. Differential intra-level item consistency should be considered in clinical applications of spatial (configural) memory tasks in order to avoid erroneous interpretations concerning sustained attention ability based on failures within levels.

Adolescent↗

PubMed2004

Inhibitory control in Obsessive-Compulsive Disorder.

The clinical features of Obsessive-Compulsive Disorder (OCD) suggest that a fundamental deficit of inhibitory control is intrinsic to the disorder. In this preliminary study, we sought to examine cognitive disinhibition in OCD by using an established laboratory technique. The stop signal task was administered to a higher functioning, untreated group of individuals with OCD, and to healthy comparison participants. Surprisingly, the OCD participants exhibited more accurate performance, suggesting better inhibitory control on this task. This unexpected finding suggests that higher functioning individuals with OCD are capable of adequate inhibition in certain contexts. It was speculated, however, that emotional stimulation might negatively affect performance and that this might be studied in subsequent research.

Adult↗

PubMed2003

Using memory strategies to improve 24-hour dietary recalls among older adults.

Dietitians commonly use 24-hour recall to obtain estimates of the typical food intakes for a population. This study was designed to determine whether using an encoding strategy or support at the time of retrieval improves older adults' 24-hour recall of food items and amounts consumed. The study included 17 older adults ranging from 74 to 91 years of age. Lunch was served to these individuals, and 24-hour dietary recall and recognition of food items consumed at the meal were conducted the following day. Portion sizes for five food items served at the meal, as well as memory tests for recall and recognition and a visual perceptual test, were also administered. Among older adults, use of an encoding strategy did not enhance memory of food items and amounts consumed. However, when the adults were provided support with a visual recognition aid at the time of food item recall, individuals remembered more food items but not amounts consumed. Performance on the Wechsler Memory Scale I and II, Verbal Paired Associates, was found to be a predictor of subjects' performance on 24-hour recall.

Aged↗

PubMed2002

Memory mechanisms in posttraumatic stress disorder.

The authors present a new theory of the neurobiological mechanisms mediating the memory processes involved in posttraumatic stress disorder (PTSD). The current fear-conditioning model accounts for learning that underlies certain central features of PTSD, but it fails to account for peritraumatic memory disturbances, episodic memory phenomena that also are characteristic of the disorder. A more comprehensive model of PTSD, consistent with the clinical phenomenology of the disorder, is proposed on the basis of observations from human memory experiments. It is argued that the amygdala is the locus of consolidation of the core of the traumatic experience and that amygdalar inhibition of hippocampal function at high levels of emotional arousal mediates diminution of conscious memory for peritraumatic events. The model is amenable to specific experimental manipulations that should yield information pertinent to further development of theory and, ultimately, to more rational clinical intervention.

Animals↗