Asian Journal of Psychiatry 7 (2014) 99–100
Contents lists available at ScienceDirect
Asian Journal of Psychiatry journal homepage: www.elsevier.com/locate/ajp
Letter to Editor Structural changes and cognitive deficits in depression and their clinical correlates Sir, The relationship between hippocampus and major depression seems to be strong but complex (Lorenzetti et al., 2009). The hippocampus also appears to have a possible role in regulation of emotion (Davidson et al., 2000) as well as executive functions (John et al., 2004). Although much research exists on this issue worldwide, there are no studies on this compelling subject on Indian population. We studied the structural and cognitive changes in major depressive disorder (MDD) by comparing the hippocampal volume and Wisconsin Card Sorting Test (WCST) performance in 50 cases of depression with 50 matched healthy controls. We went on to see if these parameters vary with the depression severity. We also compared First episode depression with recurrent depression. We found that the depressed patients had a lower left hippocampal volume as compared to the non depressed healthy controls. The right hippocampus did not differ significantly between the 2 groups. The depressed group also performed poorly on several measures of executive functions (Table 1). Depressed patients who had a past burden of depressive illness (ME) had a lower left and right hippocampal volume as compared to depressives in their first episode (FE). The FE depressives when compared to healthy controls also had hippocampal volume reduction but only on the left side. However the ME did not differ from the FE depressives in terms of performance on WCST.
Across the severity gradient (mild, moderate and severe) the depressed group did not differ in their hippocampal volume nor on any of the WCST parameters The results confirm that depressed group had smaller hippocampus, suggesting hippocampal atrophy. Also smaller hippocampal volume seen in first episode itself and higher reductions in HC volume seen in depressives with past burden of illness (recurrent depression) suggests that the hippocampal atrophy seen in depression goes on increasing with the burden of depressive illness i.e. depression is toxic to the brain. This seems to be in confirmation with the findings worldwide reported in previous such studies including a recent metanalysis (Poul and Barbara, 2004). However, to establish causality in this context, we recommend longitudinal controlled follow up studies. We did not find any correlation between hippocampal volume and depression severity, in consonance with previous studies worldwide (Frodl et al., 2002), giving credence to the ongoing debate on the need for classification of major depressive disorder based on neurobiological findings instead of purely symptom based categorization. However no significant correlation was found between the hippocampal volume and cognitive dysfunction (performance on WCST). This suggests that those depressives who have volume loss in the hippocampus may not necessarily have significant cognitive dysfunction as may be normally expected. The core structure of the hippocampus may not be involved in cognitive dysfunction seen in depression. Instead, it may be the functional connections of the hippocampus, possibly, the hippocampus – oribitomedial prefrontal circuit (which has been proposed to be involved in the integration of cognition, emotion
Table 1 Comparison of depressed and non depressed healthy group. Hippocampal volume
Depressed gp [vol. in cmm (SD)]
Control Gp [vol. in cmm (SD)]
p value
Left Right
2399.33(307.53) 2561.57(372.49)
2756.28(260.45) 2592.62(320.93)
Contents lists available at ScienceDirect
Asian Journal of Psychiatry journal homepage: www.elsevier.com/locate/ajp
Letter to Editor Structural changes and cognitive deficits in depression and their clinical correlates Sir, The relationship between hippocampus and major depression seems to be strong but complex (Lorenzetti et al., 2009). The hippocampus also appears to have a possible role in regulation of emotion (Davidson et al., 2000) as well as executive functions (John et al., 2004). Although much research exists on this issue worldwide, there are no studies on this compelling subject on Indian population. We studied the structural and cognitive changes in major depressive disorder (MDD) by comparing the hippocampal volume and Wisconsin Card Sorting Test (WCST) performance in 50 cases of depression with 50 matched healthy controls. We went on to see if these parameters vary with the depression severity. We also compared First episode depression with recurrent depression. We found that the depressed patients had a lower left hippocampal volume as compared to the non depressed healthy controls. The right hippocampus did not differ significantly between the 2 groups. The depressed group also performed poorly on several measures of executive functions (Table 1). Depressed patients who had a past burden of depressive illness (ME) had a lower left and right hippocampal volume as compared to depressives in their first episode (FE). The FE depressives when compared to healthy controls also had hippocampal volume reduction but only on the left side. However the ME did not differ from the FE depressives in terms of performance on WCST.
Across the severity gradient (mild, moderate and severe) the depressed group did not differ in their hippocampal volume nor on any of the WCST parameters The results confirm that depressed group had smaller hippocampus, suggesting hippocampal atrophy. Also smaller hippocampal volume seen in first episode itself and higher reductions in HC volume seen in depressives with past burden of illness (recurrent depression) suggests that the hippocampal atrophy seen in depression goes on increasing with the burden of depressive illness i.e. depression is toxic to the brain. This seems to be in confirmation with the findings worldwide reported in previous such studies including a recent metanalysis (Poul and Barbara, 2004). However, to establish causality in this context, we recommend longitudinal controlled follow up studies. We did not find any correlation between hippocampal volume and depression severity, in consonance with previous studies worldwide (Frodl et al., 2002), giving credence to the ongoing debate on the need for classification of major depressive disorder based on neurobiological findings instead of purely symptom based categorization. However no significant correlation was found between the hippocampal volume and cognitive dysfunction (performance on WCST). This suggests that those depressives who have volume loss in the hippocampus may not necessarily have significant cognitive dysfunction as may be normally expected. The core structure of the hippocampus may not be involved in cognitive dysfunction seen in depression. Instead, it may be the functional connections of the hippocampus, possibly, the hippocampus – oribitomedial prefrontal circuit (which has been proposed to be involved in the integration of cognition, emotion
Table 1 Comparison of depressed and non depressed healthy group. Hippocampal volume
Depressed gp [vol. in cmm (SD)]
Control Gp [vol. in cmm (SD)]
p value
Left Right
2399.33(307.53) 2561.57(372.49)
2756.28(260.45) 2592.62(320.93)
