Oligophrenia means impaired mental growth due to disease.
Such diseases may be acquired through genetics or circumstances before or after birth. If a mother has syphilis, rubella, toxoplasmosis, vitamin deficiencies, thyroid disorder, or diabetes mellitus then her baby may be born with oligophrenia. Or if the baby's blood is incompatible with the mother's or in a case of neonatal asphyxia or as the after-effects of meningitis or encephalitis. Or this condition may be part of Down's syndome. Whatever the cause may be, it is irreversible.
Often these sorts of diseases have a slight physical manifestation as well.
The effects of oligophrenia will not worsen. With proper guidance and love, a person with this diagnosis can rise above all expectations, just like anyone else.