Higher levels of thyroxine may predict a favorable response to donepezil treatment in patients with Alzheimer disease: a prospective, case-control study.

BACKGROUND: Cholinergic hypothesis has been advanced as an etiology of Alzheimer disease (AD) on the basis of the presynaptic deficit found in the diseased brains, and cholinesterase inhibitors (ChEIs) are the treatment of choice for these patients. However, only about half of treatment efficacy was found. Because increasing evidence supports an extensive interrelationship between thyroid hormones (THs), cortisol level and the cholinergic system, the aim of the present study was to evaluate thyroid function and cortisol level in patients with mild to moderate AD before and after ChEIs treatment, and to identify possible variations in response. This was a prospective, case-control, follow-up study. Levels of cortisol and THs were evaluated in 21 outpatients with mild to moderate AD and 20 normal controls. All patients were treated with 5 mg/day of donepezil (DPZ) and were reevaluated after 24-26 weeks of treatment. RESULTS: The patients had worse cognitive function, higher cortisol level, and lower levels of triiodothyronine (T3) and its free fraction than the controls. There were no significant differences in global cognitive function or cortisol level after treatment, however, significant reductions in T3 and thyroxin (T4) levels were observed. Responders had higher levels of T4 than non-responders, followed by a significant reduction after treatment. CONCLUSIONS: These results suggest that relatively higher levels of T4 may predict a favorable response to DPZ treatment. Further studies are warranted to confirm the relationship between THs and ChEIs therapy in AD and to explore new therapeutic strategies. On the other hand, cortisol levels are more likely to respond to interventions for stress-related neuropsychiatric symptoms in patients with AD rather than ChEIs treatment. Further studies are warranted to investigate the association between cortisol level and the severity of stress-related neuropsychiatric symptoms in patients with AD.

Is one day off sufficient for re-adaptation to a daytime routine after two consecutive nights of work?

Fast rotation three-shift working schedules are common in the medical field in Taiwan. This study investigated whether 24 h off is sufficient for re-adaptation to a daytime routine after working two night shifts (NSs) by comparing changes in cognitive function, anxiety state and objectively measured sleep propensity between those working two NSs followed by 24 h off (n = 21, 2NS-off) and an off-duty group (n = 21, OD). The results showed that nurses in the 2NS-off group were less alert and had decreased visual attention performance and executive function ability than the OD group during the daytime. One day off appeared to be insufficient to adapt back to a daytime shift after two NSs. Further studies are warranted to investigate whether a longer sequence of consecutive NSs (e.g. four NSs) followed by two days off is suitable for a fast rotation three-shift work schedule to allow for optimal performance throughout the next daytime shift. Practitioner Summary: The medical field in Taiwan mandates at least 24 h off between night and day shifts, but this appears to be insufficient for re-adapting to a daytime shift after two night shifts. A longer sequence of consecutive night shifts followed by two days off may be more suitable.

Four Night Shifts Have a Degree of Performance Adaptation.

OBJECTIVE: In this case control study, we investigated the process of adaptation to night shift (NS) work and recovery back to a day schedule among nurses working a fast-rotation three-shift schedule. BACKGROUND: There is limited knowledge of how specific patterns of a fast-rotation shift affect nurses' performance. METHOD: The cognitive performance of off-duty nurses (OD; n = 21), those working the first night of an NS (1NS; n = 21) and the last night of two ( n = 21), three ( n = 20), and four (4NS; n = 21) successive NSs were compared. Changes in sleep propensity, cognitive function, and anxiety were compared in the daytime after working four successive NSs followed by 24 hr off (4NS-off; n = 18) and in those off duty. RESULTS: The visual attention task (VAT) of cognitive function was significantly worse in the 1NS group and significantly better on the last night in the 4NS group than in the other NS groups. The nurses in the 4NS-off group were less alert and had poorer VAT performance than the OD group during the daytime. CONCLUSION: The nurses working on NS experienced a decrease in VAT performance due to acute changes in circadian rhythm but also significant performance adaptation after four consecutive NSs. One off-duty day was insufficient to recover back to a daytime shift after four consecutive NSs. APPLICATION: In a fast-rotation three-shift schedule, performance adaptation occurred in the nurses who worked four consecutive NSs, and more than one off-duty day are needed to recover back to daytime shift after those NSs.

Rotating night shifts too quickly may cause anxiety and decreased attentional performance, and impact prolactin levels during the subsequent day: a case control study.

BACKGROUND: We investigated circadian changes and effects on mood, sleep-related hormones and cognitive performance when nurses worked consecutive night shifts in a rapidly rotating shift system. Daytime cognitive function, sleep propensity and sleep-related hormones (growth hormone, cortisol, prolactin, thyrotropin) were compared after participants worked two and four consecutive night shifts. METHODS: Twenty-three off-duty nurses, 20 nurses working two consecutive night shifts and 16 nurses working four consecutive night shifts were enrolled. All participants completed the Maintenance of Wakefulness Test, State-Trait Anxiety Inventory, Stanford Sleepiness Scale, visual attention tasks (VAT), Wisconsin Card Sorting Test, and modified Multiple Sleep Latency Test. Hormone levels were also measured four times throughout the day, at 2-h intervals. RESULTS: During the day, the participants in the night shift groups were less able to maintain wakefulness, had poor performance on VAT, and higher thyrotropin levels than did those in the off-duty group. Participants who worked two night shifts were better able to maintain wakefulness, had higher anxiety scale scores, poorer initial performance and lack of learning effect on VAT, and higher prolactin levels compared with those who worked four night shifts. There were no differences in cortisol levels between the two- and four- shift groups. CONCLUSIONS: Rotating night shifts too quickly may cause anxiety and decreased attentional performance, and may impact daytime prolactin levels after night shifts. It is possible that the two-shift group had a higher cortisol level than did the four-shift group, which would be consistent with the group's higher state anxiety scores. The negative findings may be due to the small sample size. Further studies on the effects of consecutive night shifts on mood and cortisol levels during the daytime after sleep restriction would be valuable.

Parallel improvement of cognitive functions and P300 latency following donepezil treatment in patients with Alzheimer's disease: a case-control study.

PURPOSE: To evaluate the effect of donepezil, one of the cholinesterase inhibitors, on P300 measurements in patients with Alzheimer's disease (AD) and investigate the relationship between the subfactors of cognitive performance and P300 components. METHODS: One hundred outpatients with AD were evaluated for cognitive function (cognitive ability screening instrument) and event-related potentials before and after 22 to 23 weeks of treatment with donepezil (5 mg/day). Twenty age-matched normal control subjects were recruited. RESULTS: The patients with AD showed prolonged P300 and N200 latency, no significant differences in N100 and P200 components, and poor performance in neuropsychological assessments compared with control subjects at baseline. After donepezil treatment, the patients with AD had reduction in P300 latency at Pz lead, which was associated with a parallel improvement in cognitive function in terms of remote memory, recent memory, visual instruction, and orientation. The pre-post treatment difference of P300 latency significantly correlated with the cognitive ability screening instrument score difference and recent memory score difference, respectively. CONCLUSIONS: The patients with AD still had intact early sensory processing but impaired higher-level cognitive processes that could influence behavior deviation. The donepezil treatment, which enhances higher-level cognitive processing time, revealed that P300 latency decreases as cognitive capability increases, especially improved in recent memory.

Factors related with the ability to maintain wakefulness in the daytime after fast and forward rotating shifts.

The aim of this study was to explore changes in cognitive function, sleep propensity, and sleep-related hormones (growth hormone, cortisol, prolactin, and thyrotropin) and to investigate the factors related to the ability to maintain wakefulness in the daytime after one block of fast forward rotating shift work (2 days, 2 evenings, and 2 nights). Twenty female nurses (mean age: 26.0 ± 2.0 years; range: 22-30 years) were recruited from an acute psychiatric ward. The nurses completed the Maintenance of Wakefulness Test (MWT), State Anxiety Inventory (SAI), Stanford Sleepiness Scale (SSS), Digit Symbol Substitution Test, Symbol Searching Test, Taiwan University Attention Test, Wisconsin Card Sorting Test (WCST), and Multiple Sleep Latency Test (MSLT) four times throughout the day at 2-hour intervals, and their hormone levels were measured at the same time. There was no time of day effect on sleep propensity as measured by the MWT or MSLT despite an increase in self-reported sleepiness. Anxiety state and neuropsychological tasks, including executive function, attention, and perceptual and motor abilities were not affected during the daytime sleep restriction period. The number of omissions and perceptual and motor abilities showed a practice effect. The thyrotropin levels were significantly elevated, and cortisol levels significantly decreased during the daytime sleep restriction period. There were no significant changes in growth hormone or prolactin throughout the daytime period. Age was negatively associated with the mean sleep latency (MSL) of the MWT and positively associated with the MSL of the MSLT. The perseverative errors in WCST and SSS scores were negatively associated with the MSL of the MWT. SAI scores and thyrotropin levels were positively associated with the MSL of the MWT. In conclusion, there was no change in sleep propensity in the daytime after one block of rotating shift work. An attempt to preserve daytime alertness was also related to maintaining neuropsychological performance. Maintaining this ability was related to thyrotropin and age, and this cognition required a high attentive load.

Nurses working on fast rotating shifts overestimate cognitive function and the capacity of maintaining wakefulness during the daytime after a rotating shift.

OBJECTIVES: The objective of our study was to explore changes in cognitive functions, sleep propensity, and sleep-related hormones (growth hormone [GH], cortisol, prolactin [PRL], thyrotropin [TSH]) in the daytime of nurses working on fast rotating shifts. METHODS: Twenty nurses who worked two consecutive night shifts and 23 off-duty nurses were recruited from an acute psychiatric ward. The maintenance of wakefulness test (MWT), Stanford sleepiness scale (SSS), visual attention tasks, Wisconsin card sorting test (WCST), multiple sleep latency test (MSLT), and measuring hormones were administered four times throughout the daytime at 2-hour intervals. RESULTS: The subjects in the off-duty group were more able to maintain wakefulness than those in the night-shift group; however, there were no differences in self-reported total sleep time or sleep latency on the MSLT and SSS scores between the two groups. The subjects in the night-shift group had poorer performances on visual attentive tasks and higher levels of TSH than those in the off-duty group, and this resulted in a lack of a learning effect on the tasks that required a high attentive load. CONCLUSIONS: Nurses working on fast rotating shifts overestimate the cognitive functions and capacity of maintaining wakefulness following daytime sleep restriction. Attention performance depended on the attentive load requirement and was possibly related to TSH level.