Early dementia often caused by autoimmune disorders

By Martha Kerr

NEW YORK (Reuters Health) - Dementia in patients who are younger than 45 years of age is often caused by degenerative, metabolic or autoimmune diseases, Dr. Brendan Kelley, of the Mayo Clinic in Rochester, Minnesota, told attendees at the 60th annual meeting of the American Academy of Neurology, being held this week in Chicago.

Kelley and colleagues searched the Mayo Clinic database for patients who began to develop dementia between 17 and 45 years that was not related to trauma, brain infections or mental retardation. They identified 235 such patients receiving care between 1996 and 2006. The average age at dementia onset was 34.7 years.

Neurodegenerative causes accounted for dementia in 29.8 percent of the group, frontotemporal dementia occurred in 13.2 percent and Alzheimer's disease was seen in less than 1 percent," data presented by Kelley showed.

Autoimmune-inflammatory causes, including multiple sclerosis, accounted for 21.2 percent. Inborn errors of metabolism were identified in 10.6 percent.

At the last evaluation, the cause of dementia was still unknown in 44 patients (18.7 percent) despite exhaustive evaluations, Kelley reported.

Inborn errors of metabolism were more common in individuals with symptoms appearing before age 30. Neurodegenerative causes were more common in dementias occurring after age 35.

"Some of the important causes, such as lupus, metabolic disorders, Huntington chorea, among others, can occur in very young children," Kelley told Reuters Health. "Only 4 of the 235 cases in our series resembled Alzheimer's type dementia."

"It is important to increase awareness that dementia can and does occur in young patients," Kelley continued. "This is important for social services and other aid-giving organizations to know."

"Symptoms in younger patients have more of a neuropsychiatric focus, with a lot of psychiatric features," he said. These patients can be misdiagnosed with psychiatric disorders, such as schizophrenia.

The causes of young-onset dementia are more often hereditary or genetic than they are in older patients with dementia.

"We are now looking to determine which clinical features are more classic...which clinical features to focus on," Kelley said. "This is a single disorder with multiple underlying causes. Treating the causes may correct to some extent the disorder."