A weakness of the cognitive explanation of depression?

-Alternative explantion: like biological origin or genetic inheritance or disruption for neurotransmitters -Zhang et al conducted reserach on the role of serotonin has found lower levels in patients with depression and also found a gene related to this which is x10 more common with depression -In addition, drug therapies, including SSRI's which increase the level of serotonin, are found to be effective in the treatment of depression -This provides support for the role of biological factor sin the development of depression and therefore casts doubt on the cognitive explanation as credible, sole cause of the disorder.