Adult MLD is characterized by normal development through puberty with symptoms presenting at a later age, generally from the twenties through the forties. Similar to the Juvenile cognitive form, the initial signs of adult onset are often changes in cognitive abilities and personality. The prognosis for MLD is poor. Most children within the infantile form die by age 5. Symptoms of the juvenile form progress with death occurring 10 to 20 years following onset. Those persons affected by the adult form typically die withing 6 to 14 years following onset of symptoms.
Children diagnosed with late infantile MLD typically live another five to 10 years. In juvenile MLD, the life expectancy is 10 to 20 years after diagnosis. If the symptoms don’t appear until. Adult MLD can begin during the teen years, but in some people may not appear until the 40s or 50s. Diagnosing MLD usually involves MRI scans of the brain, which typically show changes in the myelin sheath and nerve fibers (white matter) of the brain's hemispheres.