A new study has found that learning disabilities are associated with language problems later in life.
The study found that individuals with a neurodegenerative condition affecting language appear more likely to have had a history of learning disabilities than those with other types of dementia or with no cognitive problems.
The condition, known as primary progressive aphasia, causes individuals to lose language abilities as they age, even though their other brain functions appear unaffected for at least the first two years.
For the study, the research team examined a group of 699 individuals, 108 with primary progressive aphasia, 154 with Alzheimer's disease, 84 with a related disorder known as frontotemporal dementia and 353 controls without dementia.
During their enrolment, participants completed a detailed demographic and medical history interview that included two questions about whether they or immediate family members had a history of learning disabilities.
The team conducted a medical record review for the 23 individuals with primary progressive aphasia who reported either a personal or family history of learning disability.
The researchers found that patients with primary progressive aphasia were more likely to have had learning disabilities or a close family member with learning disabilities than were those with other forms of dementia or without dementia.
The review of patients with both aphasia and learning disabilities showed families with unusually high rates of learning problems, especially dyslexia.
The study suggests that some individuals or families may have an underlying susceptibility to difficulties with the language network.
"This relationship may exist in only a small subgroup of persons with dyslexia without necessarily implying that the entire population with dyslexia or their family members are at higher risk of primary progressive aphasia," the authors said.
The study is published in the February issue of Archives of Neurology, one of the JAMA/Archives journals.