Paresis also called brain syphilis, syphilitic meningoencephalitis, general paralysis of the insane, or dementia paralytica, psychosis caused by widespread destruction of brain tissue occurring in some cases of late syphilis. Mental changes include gradual deterioration of personality, impaired concentration and judgment, delusions, loss of memory, disorientation, and apathy or violent rages. Convulsions are not uncommon, and while temporary remissions sometimes occur, untreated paresis is eventually fatal.
I've seen a couple of cases where the person had had syphilis for 20 plus years - not pretty.
