Poison ivy and other poison plant rashes canât be spread from person to person. But it is possible to pick up the rash from plant oil that may have stuck to clothing, pets, garden tools, and other items that have come in contact with these plants.
Biological Causes. Some individuals are more vulnerable to depression than others due to their own unique biological factors, such as presence of depression-triggering genes. This means that depression is hereditary; hence it tends to run in families, notes the Black Dog Institute.nother biological trigger of depression is abnormal brain structure and chemistry. The report released by the National Institute for Mental health notes that the brain structure of an individual with depression is slightly different from the rest of individuals who do not have the disorder.
The current research indicates that biological and genetic risk factors (or predisposition) are fundamental to mental illnesses, but psychological factors are also believed to play a factor both in the incidence (whether a person develops a mental illness) and outcomes (how well they recover from a mental illness).