L14 Flashcards
When rosenthal et al. initially studied SAD, they recruited ___ patients from a local community with a history of ___ and who had experienced for at least __ consecutive years, depression that developed during the ___ or ____ and remitted during the following spring or summer.
29, MDD, 2, fall, winter
Symptoms of SAD included sadness, ___, and irritability, decreased __ ____, changes in appetite and a craving for _____, increased total ____ time, and daytime ____.
anxiety, physical activity, carbohydrates, sleep, drowsiness
Rosenthal discovered that the percentage of subjects experiencing depression in ____ was 100%, when the daily ____ and _____ for the town was the lowest of all months.
january, photoperiod, temperature
Subjects in rosenthal’s experiment got 2 weeks of ____ ____ 3 hours before dawn or 3 hours after dusk. They either received a ____ light (daytime sunlight mimic) or a dim ____ light (mimics sunrise / ____ light). There was a decrease in symptoms with the light mimicking ______ light, but not the dim yellow light.
light therapy, blue, yellow, sunset, daytime
type of recurrent major depression, wherein depression begins and ends during a specific season each year
seasonal affective disorder
mild symptoms of SAD can be considered the ___ ___, or ____ ____. Severe symptoms of SAD are often debilitating symptoms seen in non-seasonal ____.
winter blues, subsyndromal SAD, MDD
Hypotheses on SAD pathophysiology include ____ ___, ____ function, and ____
circadian rhythms, neurotransmitter, genetics
Circadian rhythmicity is maintained by the central pacemaker in the ____, the ____, which entrains internal circadian rhythms to external time cues (____). Circadian ____ occurs when there is asynchrony between the SCN rhythm and ____.
hypothalamus, SCN, zeitgeber, misalignment, behaviour
______ displays robust circadian rhythm and plays a critical role in synchronizing the sleep-wake cycle with the ____ cycle. It peaks a little after ____, and ___ in the morning.
melatonin, light-dark, midnight, decreases
Circadian rhythm phase of melatonin can be described by the ___ ___ ______ _____, or the temporal onset of melatonin rise. Light exposure in the evening results in a ____ ____ of melatonin rhythm. If the wake-up time remains constant, but light exposure is still given in the evening, the phase-delayed melatonin rhythms results in a smaller __ ____ with the sleep wake cycle (has shorter rise and fall). Light exposure in the ___ can correct a phase-delayed rhythm by causing a ______
dim light melatonin onset, phase delay, phase angle, morning, phase-advance
melatonin is a small, _____, ______ ____ derived hormone that is primarily synthesized and secreted on demand by ____ in the pineal gland. It is metabolized quickly, with a half life of ___ minutes, and production is tightly regulated by ________ _____ release.
non polar, amino acid, pinealocytes, 30, sympathetic norepinephrine
when there is light, the light reaches the ___ ____ ____, then travels to the ___ which inhibits the ____.
retinal hypothalamic tract, SCN, PVN
In the darkness, the RHT has ___ ____, leading to no activation in the SCN, and ___ of the PVN. This PVN activity travels to the _____ ___ ____, which release ____ onto alpha-1 or ____ receptors on the ______. This then leads to the activation of ___ and subsequently ____, which activates ____ directly or indirectly by _____. ____ returned to the cell by monoamine transporters is converted to ______. This product is then converted to ___ by a protein ____ by PKA. Then melatonin diffuses into the bloodstream
no activation, disinhibition, sympathetic nervous system, NE, beta-1, pinealocyte, DAG/IP3, PKC, PKA, cAMP, serotonin, N-acetylserotonin, melatonin, phosphorylated
Exposure to a ____ light induces a reduction in melatonin release, while this is not seen in a ___ shifted light.
white/blue, green
a ____ light perception is not necessary for photoregulation of melatonin release. This is shown in patients with ___ ____, who have a damaged _____ ______. In these people, light does ___ affect melatonin release, and they lack a typical ___ hour circadian rhythm. However, patients with ___ ___ ____, where the retinal-hypothalamic tract is preserved, light induced a ___ of melatonin release, even though the patient had no ____ awareness of the light
conscious, congenital glaucoma, retinal-hypothalamic tract, not, 24, congenital retinal dystrophy, suppression, conscious
Photosensitivity ___ with age. Older people wake up ___ in the morning and have ___ during the day
decrease, earlier, naps
Rodent models of SAD like symptoms exist. Nile grass rats are ___ and exposure to a short photoperiod cycle of _____ light and ____ dark for ___ weeks induces depressive like behaviours on ___ ___ test (anhedonia) and the ____ ___ ___ (helplessness) relative to controls.
diurnal, 5 hr, 19 hr, 6, sucrose preference, forced swim test
Wistar rats that are exposed to constant darkness or constant ____ (disrupts it more) for ___ weeks disrupts daily rhythmic activity. Exposure to constant light but not constant darkness induced ____ and ___ like responses on the sucrose preference test and ________ on an ____ ___ ___ compared to controls. It also abolished circadian fluctuations of ____ and _____. instead of high CORT / melatonin at night and low CORT / melatonin in the day, there was ___ CORT in both night and day, and ___ melatonin in both. This was likely driven by ___ of the SCN cells
light, 8, depressive, anxiety, grooming, open field test, cortisol, melatonin, high, low, hypoactivity
The hypothesis that SAD is induced by a shorter winter photoperiod
photoperiod hypothesis
Support for the photoperiod hypothesis includes that SAD tends to be more prevalent in regions ___ from the equator in the ___ ____, such as the ____ and ____. Additionally, SAD patients show ___ melatonin duration in the winter than in the summer, which is not seen in ____ controls. Moreover, ______ ____ via an artificial light is effective in treating SAD. When a ___ light is paired with an _____ such as citalopram or ____, this is more effective in treating SAD
farther, northern latitude, UK, Alaska, longer, healthy, photoperiod extension, bright, antidepressant, sertraline
Problems with the photoperiod hypothesis include that it doesn’t explain the phenomenon of ___ ___ SAD, which involves poor ____, ___, weight loss, ____, agitation, restlessness, anxiety, and episodes of ____ behaviour. Moreover, if SAD is induced by a shorter winter photoperiod, then light therapy should be equally effective whether you add on daylight in the ___ or in the ____. However, giving light therapy in the ___ seems to be more effective than therapy in the night.
summer pattern, appetite, irritability, insomnia, violent, morning, night, morning
hypothesis proposed by lewy et al., that says that SAD results from internal circadian rhythms that are phase delayed relative to the external clock or other rhythms such as the sleep-wake cycle
phase-shift hypothesis
support for the phase shift hypothesis comes from the fact that light therapy exerts its effects by correcting the ___ phase delay, ie. by brining the light-sensitive circadian clock to match that of the ____ cycle.
abnormal, sleep-wake
problems with the phase-shift hypothesis include that while it is a stronger hypothesis than the photoperiod hypothesis, there is ___ evidence of phase shift in ____ patients. Moreover, other circadian rhythms should show ____, but they do not. ____ ____ rhythms, ____ rhythms, and ____ ____ hormone rhythms do not change post treatment
minimal, SAD, misalignment, body temperature, cortisol, thyroid stimulating
