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K Cadenhead

Publications and source records attributed to K Cadenhead.

6 recordsLinked to original sources
PubMed2001

Matching strategies for drug studies of prepulse inhibition in humans.

Prepulse inhibition (PPI), a measure of sensorimotor gating, is impaired in certain neuropsychiatric disorders. Animal studies have revealed drug effects on PPI that may be relevant to understanding the biology of gating deficits in human populations. Recent efforts have examined similarities and differences in drug effects on PPI between rodents and humans. Experimental designs are needed that most effectively translate these drug studies across species. In the course of a larger set of studies of drug effects on startle in normal human subjects, we examined the potential utility of one design element that is utilized in rodent PPI drug studies: pre-testing to diminish variability across dose groups. Startle was measured during a screening session; 7-10 days later, 20 subjects were retested after consuming a placebo pill. Acoustic and tactile startle, and unimodal and cross-modal PPI, were measured in five sessions over a period of 3 hours post-placebo. There were significant and robust correlations between levels of startle magnitude and PPI during pre-testing and testing, for both left and right eyeblink measures. Comparable correlations were evident for both unimodal and cross-modal testing. Pre-testing values were most predictive of test performance early in the 3-hour test session, and predictive strength diminished or disappeared towards the end of testing. The utility of a pre-testing design could be seen clearly by comparing groups 'matched', based on pre-test data, versus groups created by alternating or random group assignments. It is concluded that pre-test designs can effectively match groups with comparable levels of startle or PPI, and thereby diminish between-group variability in human PPI drug studies. For studies using repeated testing to assess drug time course, the predictive value of pre-testing is greatest in early test sessions.

Acoustic Stimulation↗
PubMed1999

Sex differences in sensorimotor gating of the human startle reflex: all smoke?

RATIONALE: A recent report described sex differences in the effects of nicotine use and withdrawal on prepulse inhibition of acoustic startle (PPI), but no sex differences in PPI in non-smokers. OBJECTIVE: To determine whether previously reported male>female acoustic PPI reflect sex differences in smoking effects on PPI, rather than simple sex differences in the regulation of PPI. A retrospective analyses of >600 carefully screened normals tested over the past 12 years was completed. RESULTS: Male>female acoustic PPI was detected in analyses that included: 1) all subjects; or 2) self-declared non-smokers. CONCLUSIONS: Sex differences in PPI cannot be accounted for by smoking history, because they are present across a large sample of non-smoking normal controls.

Acoustic Stimulation↗
PubMedDate not supplied

Clinical and experimental characteristics of "hypothetically psychosis prone" college students.

The study of individuals at the boundaries of schizophrenia has historically involved genetic relatives of schizophrenia patients or individuals who meet criteria for schizotypal personality disorder (SPD). Recently, many investigators have turned to the use of psychometric scales, developed to measure psychotic traits or vulnerability to developing schizophrenia, to screen large populations of college students in order to identify individuals who are "psychosis prone" or "schizotypal". To help answer the question of whether students identified with psychometric scales are indeed psychosis prone, we screened 1115 college students with the Perceptual Aberration/ Magical Ideation (PerMag) and Physical Anhedonia (PhysAn) Scales. Individuals who scored 2 standard deviations (SD) above the mean on the scales were selected as experimental subjects (N = 13 PerMag, N = 10 PhysAn) and a subpopulation of matched subjects who scored less than 0.5 SD above the mean were selected as control subjects (N = 24). All subjects then received a full battery of tests, including structured clinical interviews, the MMPI, and psychophysiological measures of information processing, including prepulse inhibition and habituation of the human startle response, visual backward masking and reaction time measures. The results suggest that the PerMag scale, but not the PhysAn scale, identifies individuals with some psychotic, affective and anxiety symptoms when compared to the controls. Neither scale predicts a diagnosis of schizotypal personality disorder or deficits on measures of information processing that characterize schizophrenia or schizotypal personality disordered patients.

Female↗