People who have long-term, recurrent depression eventually develop smaller hippocampi in their brains, according to research published in Molecular Psychiatry. And University of Sydney psychiatrist Ian Hickie, a co-author of the study, told The Guardian that there exists “a good bit of evidence” that antidepressants provide a neuroprotective effect against such hippocampal shrinkage. Hickie apparently did not clarify to The Guardian, however, that the particular study he’d just co-authored had actually found the exact opposite — that antidepressants were associated with greater hippocampal shrinkage.
“Using magnetic resonance imaged (MRI) brain scans, and clinical data from 1,728 people with major depression and 7,199 healthy individuals, the study combined 15 datasets from Europe, the USA and Australia,” stated a press release about the study from a large, international team of researchers. Most areas of the brain were not different between the groups, except for generally slightly smaller hippocampi in people who’d had a major depressive disorder (MDD) diagnosis for years. “(P)eople who had a first episode of major depression (34 per cent of study subjects with major depression) did not have a smaller hippocampus than healthy individuals, indicating that the changes are due to the adverse effects of depressive illness on the brain” over long time periods, stated the press release.
“This large study confirms the need to treat first episodes of depression effectively, particularly in teenagers and young adults, to prevent the brain changes that accompany recurrent depression,” co-author Hickie said in the press release.
An article about the study in The Conversation then stated that the study had “proved once and for all that recurrent depression shrinks the hippocampus” and “conclusively” causes “brain damage” that leads “to a loss of emotional and behavioural function.”
Critical commenters prompted the Conversation article author to follow up again with Hickie and then change the article text to indicate that this “brain damage” was readily “reversible.” Meanwhile, in The Guardian article, Hickie clarified that the hippocampus wasn’t so much actually being damaged or losing cells as a result of depression, but temporarily losing “connections between cells”, in the same way that can happen to anyone who might “sit in a room doing nothing” a lot.
The Guardian also reported that, “There was some evidence that the hippocampus was larger in those patients taking antidepressants, Hickie said, indicating these medications could have a protective effect.” The Guardian then quoted Hickey to that effect: “There is a lot of nonsense said about antidepressants that constantly perpetuates the evils of them, but there is a good bit of evidence that they have a protective effect.” However, these statements appeared to exist in direct opposition to the evidence provided in the actual study co-authored by Hickie.
The study in Molecular Psychiatry did not provide detailed data on what percentages of participants were taking psychiatric medications or for how long they may have taken them previously; however, some analysis was included about medication users. “With respect to the moderating effects of medication use, no significant effect of the percentage of patients taking antidepressants was observed, only a trend-wise lower hippocampal volume in MDD patients in samples with a higher percentage of patients taking antidepressants,” the study stated.
The authors cited other studies that have suggested that antidepressants could hypothetically have a neuroprotective effect “by enhancing synaptic plasticity, neurotrophic processes and putatively neurogenesis”. However, the authors then noted that this notion that antidepressants could provide such neuroprotective effects “appears to contradict our current observation” in which they found a “trend effect” of “lower hippocampal volume in antidepressant medication users compared to controls”.
They stated that these differences disappeared when they controlled for depression recurrence, and then concluded that, “(I)ntervention studies with pre- and post-antidepressant treatment comparisons are needed to clarify the impact of antidepressant use on hippocampal volume.”
Schmaal, L, D J Veltman, T G M van Erp, P G Samann, T Frodl, N Jahanshad, E Loehrer, et al. “Subcortical Brain Alterations in Major Depressive Disorder: Findings from the ENIGMA Major Depressive Disorder Working Group.” Mol Psychiatry, June 30, 2015. http://dx.doi.org/10.1038/mp.2015.69. (Full text)
Chronic depression shrinks brain’s memories and emotions (The Guardian, June 30, 2015)
Patients with recurrent depression have smaller hippocampi (University of Sydney press release on MedicalXpress, June 29, 2015)
Depression damages parts of the brain, research concludes (The Conversation, June 30, 2015)