Pathophysiological mechanism of seasonal affective disorder.

Despite the long history in medicine, the pathophysiological mechanism(s) of seasonal affective disorder (SAD) remain largely unknown. By employing a meta-analytic methodology, the authors of this study attempted to verify the validity of different pathophysiological mechanism(s) proposed for SAD. The findings showed that for phototherapy of medium light intensity, a combination of morning-evening therapy regime yielded the best therapeutic effect, and the antidepressant effect of the morning-evening light regime was superior to a single pulse of light administered at other times of day. Furthermore, the data showed that the antidepressant effect of a single pulse of light was similar for morning, midday, and evening light. These findings supported the photon-count hypothesis and refuted the proposed photoperiod, melatonin, and phase-shifting models of SAD.

Spectral properties of phototherapy for seasonal affective disorder: a meta-analysis.

The general therapeutic effect of light on seasonal affective disorder (SAD) has been widely acknowledged. However, the antidepressant effect of light does not seem to be the same for different spectra of light. In this study, the authors attempted to study the spectral properties of phototherapy for SAD using a meta-analytical procedure. The findings suggested that light of short to medium wavelengths (blue/green/yellow) seem to be essential for the therapeutic effect of light on SAD. Red wavelengths were relatively ineffective. It was then postulated that SAD may be predisposed and/or precipitated by the inefficiency of the S and M cones in the retina. Furthermore, ultraviolet (UV) waves did not seem to be essential for SAD symptom alleviation by artificial light. Therefore, these potentially harmful UV waves should be blocked in any clinical application of phototherapy for SAD.

Correlational structure of the MCMI-III personality disorder scales and comparisons with other data sets.

We examine the correlational structure of the personality disorder (PD) scales from the MCMI-III (Millon, 1994) among 614 college students. The correlation matrix from our nonclinical sample was highly similar to the clinical sample matrices reported by Millon (1994). Further analyses revealed that the correlation matrices from a variety of MCMI data sets are generally similar to one another, but are only moderately similar to PD correlation matrices based on other assessment techniques. PD correlation matrices based on different assessment techniques are generally not very similar to one another. Two-, 3-, and 4-factor solutions for the MCMI-III PD scales are reported and provide a framework for integrating apparently conflicting findings from previous work. The 4-factor solution was most meaningful and was consistent with the 5-factor model of PD.