TY - JOUR

T1 - Season-independent cognitive deficits in seasonal affective disorder and their relation to depressive symptoms

AU - Hjordt, Liv Vadskjær

AU - Stenbæk, Dea Siggaard

AU - Ozenne, Brice

AU - Mc Mahon, Brenda

AU - Hageman, Ida

AU - Hasselbalch, Steen Gregers

AU - Knudsen, Gitte Moos

N1 - Copyright © 2017 Elsevier B.V. All rights reserved.

PY - 2017/11

Y1 - 2017/11

N2 - Although cognitive impairments are common in depressed individuals, it is unclear which aspects of cognition are affected and whether they represent state or trait features of depression. We here exploited a naturalistic model, namely the seasonal fluctuations in depressed status in individuals with Seasonal Affective Disorder (SAD), to study depression-related cognition, longitudinally. Twenty-nine medication-free individuals diagnosed with winter-SAD and 30 demographically matched healthy controls with no seasonality symptoms completed the Letter-number Sequencing task (LNS), the Symbol Digit Modalities Test (SDMT) and the Simple Reaction Time (SRT) twice; in summer and in winter. Compared to controls, SAD individuals showed significant season-independent impairments in tasks measuring working memory (LNS), cognitive processing speed (SDMT) and motor speed (SRT). In SAD individuals, cognitive processing speed was significantly negatively associated with the seasonal change in SAD depressive symptoms. We present novel evidence that in SAD individuals, working memory, cognitive processing- and motor speed is not only impaired in the winter but also in the summer. This suggests that certain cognitive impairments are SAD traits. Furthermore, impairments in cognitive processing speed appear to be related to depressive symptoms in SAD. Reduced processing speed may thus constitute a SAD vulnerability trait marker.

AB - Although cognitive impairments are common in depressed individuals, it is unclear which aspects of cognition are affected and whether they represent state or trait features of depression. We here exploited a naturalistic model, namely the seasonal fluctuations in depressed status in individuals with Seasonal Affective Disorder (SAD), to study depression-related cognition, longitudinally. Twenty-nine medication-free individuals diagnosed with winter-SAD and 30 demographically matched healthy controls with no seasonality symptoms completed the Letter-number Sequencing task (LNS), the Symbol Digit Modalities Test (SDMT) and the Simple Reaction Time (SRT) twice; in summer and in winter. Compared to controls, SAD individuals showed significant season-independent impairments in tasks measuring working memory (LNS), cognitive processing speed (SDMT) and motor speed (SRT). In SAD individuals, cognitive processing speed was significantly negatively associated with the seasonal change in SAD depressive symptoms. We present novel evidence that in SAD individuals, working memory, cognitive processing- and motor speed is not only impaired in the winter but also in the summer. This suggests that certain cognitive impairments are SAD traits. Furthermore, impairments in cognitive processing speed appear to be related to depressive symptoms in SAD. Reduced processing speed may thus constitute a SAD vulnerability trait marker.

KW - Journal Article

U2 - 10.1016/j.psychres.2017.07.056

DO - 10.1016/j.psychres.2017.07.056

M3 - Journal article

C2 - 28780278

VL - 257

SP - 219

EP - 226

JO - Psychiatry Research

JF - Psychiatry Research

SN - 0165-1781

ER -