Reproducibility of the pupillary light reflex over short intervals in psychiatric patients and community volunteers.

The pupillary light reflex (PLR) is a method for measuring dynamic responses within the autonomic nervous system, and would have potential value as a point-of-care test in a psychiatry clinic if reproducible results could be obtained in a short period of time. We collected PLR from adult community volunteers and depressed outpatients with the purpose of demonstrating (1) that valid data could be obtained >90% of the time from both the community volunteers and the patients, and (2) that reproducible results could be obtained with repeated measurement over short periods of time. Valid data were captured for 90.3% of 76 participants, allowing for two attempts of the PLR per participant. Success rates were similar for depressed patients and community volunteers. Eighteen of these 76 participants provided repeated paired measurements after 5 and 10 min of dark adaptation, producing high correlations for maximum constriction velocity (MCV) between assay 1 and 2 (Pearson's r = 0.71, p < 0.001), but there was a significant 8% increase in velocity for MCV between assay 1 and 2 (∆ = 0.34 ± 0.59 mm/s, p < 0.05). In contrast, PLR measurements were stable when tested in a separate cohort of 21 additional participants at 10 and 15 min of dark adaptation with an MCV Pearson's correlation of r = 0.84, p < 0.001, with a nonsignificant 1% difference between the two time points. These findings indicate an acceptable rate of collecting valid and reproducible PLR data when contrasting two measurements of PLR after 10 or 15 min of dark adaptation in depressed and suicidal patients.

Relationships among insomnia, executive function, and suicidal ideation in depressed outpatients: A mediation analysis.

Insomnia is a risk factor for suicide, and both are associated with cognitive problems. However, prior research has not examined insomnia, cognition, and suicidal ideation within one sample. We describe cross-sectional associations among insomnia, psychomotor speed, set shifting, and suicidal ideation in 85 depressed adults. Greater insomnia was associated with slower psychomotor speed, while slower psychomotor speed was associated with a greater level (i.e., elaboration of suicide planning) and intensity of suicidal ideation in the past week. Slower set shifting was associated with a greater level and intensity of suicidal ideation in the past week. Mediation analysis indicated that psychomotor speed and set shifting both had a significant total effect on the intensity of suicidal ideation in the past week; set shifting also had a significant total effect on the sum of intensity and suicidal ideation level in the past week. The level of insomnia explained only small percentages of the total effect of either psychomotor speed or set shifting on the intensity of suicidal ideation and the sum of intensity and suicidal ideation level. The findings in this sample demonstrate significant associations of slower psychomotor speed and set shifting with suicidal ideation, with negligible contribution from insomnia.