"The basic idea is that depression and the genes that promote it were very adaptive for helping people—especially young children—not die of infection in the ancestral environment, even if those same behaviors are not helpful in our relationships with other people," says psychiatrist Charles Raison.Credit: iStockphoto
Depression is common enough – afflicting one in ten adults in the United States — that it seems the possibility of depression must be “hard-wired” into our brains. This has led biologists to propose several theories to account for how depression, or behaviors linked to it, can somehow offer an evolutionary advantage.
Some previous proposals for the role of depression in evolution have focused on how it affects behavior in a social context. A pair of psychiatrists addresses this puzzle in a different way, tying together depression and resistance to infection. They propose that genetic variations that promote depression arose during evolution because they helped our ancestors fight infection.
An outline of their proposal appears online in the journal Molecular Psychiatry. [continue reading…]
Stimulating the brain with a weak electrical current is a safe and effective treatment for depression and could have other surprise benefits for the body and mind, a major Australian study of transcranial Direct Current Stimulation (tDCS) has found.
Medical researchers from the University of New South Wales (UNSW) and the Black Dog Institute have carried out the largest and most definitive study of tDCS and found up to half of depressed participants experienced substantial improvements after receiving the treatment.
A non-invasive form of brain stimulation, tDCS passes a weak depolarising electrical current into the front of the brain through electrodes on the scalp. Patients remain awake and alert during the procedure.
“We are excited about these results. This is the largest randomised controlled trial of transcranial direct current stimulation ever undertaken and, while the results need to be replicated, they confirm previous reports of significant antidepressant effects,” said trial leader, Professor Colleen Loo, from UNSW’s School of Psychiatry.
During depression, the brain becomes less plastic and adaptable, and thus less able to perform certain tasks, like storing memories. Researchers at the Swedish medical university Karolinska Institutet have now traced the brain’s lower plasticity to reduced functionality in its support cells, and believe that learning more about these cells can pave the way for radical new therapies for depression. “We were able to cure memory dysfunction in ‘depressed’ rats by giving them doses of D-serine,” says Mia Lindskog, biologist and Assistant Professor at Karolinska Institutet’s Department of Neuroscience.
Dr Lindskog and her team used FSL rats, which are rats that have been specially bred with a disposition for ‘depression’. The rats were first put through two tests to confirm that they had the symptoms that are also characteristic of human depression. In the first, the rats’ memories were checked by repeatedly being exposed to different objects; in the second, the team assessed their level of apathy by releasing them in a container of water and observing whether they merely stayed floating in the container or immediately tried to climb out (non of the rats had to stay in the water for more than five minutes). In both cases the FSL rats’ results were compared with normal laboratory rats, and memory disorders and apathy could be confirmed.
The researchers then injected the rats with D-serine. This substance improved their memories but had no effect on the apathy. “We have shown that there are two symptoms here that can be influenced independently of one another, which means they could be treated in tandem in patients with depression,” says Dr Lindskog. The researchers also studied the synaptic activity in the hippocampus of the rats, a part of the brain which plays an important part in the memory. [continue reading…]
Do antidepressants work? Since the introduction of Prozac in the 1980s, prescriptions for antidepressants have soared 400 percent, with 17 million Americans currently taking some form of the drug. But how much good is the medication itself doing? “The difference between the effect of a placebo and the effect of an antidepressant is minimal for most people,” says Harvard scientist Irving Kirsch. Will Kirsch’s research, and the work of others, change the $11.3 billion antidepressant industry? Lesley Stahl investigates. Read Story: Treating Depression: Is there a placebo effect?
CautionIf you are depressed you should see your doctor. If you are already on Anti-depressants you should not stop taking them
