The DSM-5 (or DSM V) distinguishes between mild (slight cognitive impairment) and major (full out dementia) forms of neurocognitive disorders.
The DSM-5, (Diagnosis and Statistical-manual of Mental-disorders 5th edition), was published in 2013 by the American Psychiatric Association (APA). Mostly used by psychiatrists to classify their patients' disease.
In the chapter of DSM-5: Neurocognitive Disorders, it was added the diagnoses of mild neurocognitive disorder and major neurocognitive disorder (this is not present in the DSM 4 (1993)).