biologinė psichiatrija - Psichofiziologijos ir reabilitacijos institutas ...

Mokslo darbai, apžvalgaThis means that the same triggered activities (by the SCN)are induced at a later time in the day (24–hour clock) than innon SAD patients. Empirical data suggest that when a personis exposed to bright light during the light hours, the SCN isstimulated to induce its activities at an early time in the 24–hour cycle. This is termed ‘phase-advance’ circadian rhythm.If it is administered to a SAD patient, the ‘phase-advance’ issuperimposed on a ‘phasedelay’ status, which may bring thesystem (e.g. the SCN) to an equilibrium, normalizing circadianrhythms, and at the same time ameliorating the depressivesymptoms of SAD [14].Treating mood disorders byaltering the circadian cycleSleep deprivation therapyTreatment with sleep deprivation may offer valuable cluesto the mechanisms that underlie rapid treatment of depression.Sleep deprivation has been used to treat more than 1000depressed patients worldwide in more than 60 studies and isconsistently reported to produce rapid (within 24–48 h) reversalof depressive symptoms in approximately 40–60% ofdepressed patients [15]. Sleep deprivation protocols vary, butessentially, the depressed patient is kept awake all night (totalsleep deprivation) or part of the night (partial sleep deprivation).By the next morning, approximately half of depressedpatients experience a dramatic improvement in mood whichcontinues throughout the day. Relapse is common followingrecovery sleep; however, recent studies suggest that the responsecan be prolonged with adjunctive treatments whichinclude antidepressant medications and mood stabilizers (e.g.lithium) and chronobiological (e.g. light therapy, sleep phaseadvance) interventions. Even the most difficult to treat patients(treatment resistant) may respond to sleep deprivation [16].Bright light therapy or dawn simulationBrigzt light therapy is an effective treatment for some depressedpatients. This circadian use of brightlight therapy fordepression activates the SCN, inhibiting corticotrophin-releasinghormone release and suppressing hypothalamic–pituitary–adrenal activity [17]. Impairment in the normal mechanismsthat ‘turn off’ hypothalamic–pituitary–adrenal activation canproduce behavioural manifestations and neuro–vegetative responsessimilar to those seen in major depressive disorder includingchanges in sleep, appetite, concentration, motivation,pleasure seeking and psychomotor alterations [18].Twenty three studies met inclusion criteria, and 20 providedsufficient data for meta-analysis. Compared to placebo,bright light treatment reduced the symptoms of seasonal affectivedisorder (eight RCTs; 360 people; effect size: 0,84,95% CI 0,60 to 1,08; p