Analysis of a large group of patients with amyotrophic lateral sclerosis (ALS) has shown that patients who also have dementia at diagnosis are more likely to have bulbar-onset ALS, a subtype of the disease in which patients first experience symptoms in the head and neck, including trouble speaking or swallowing.
These patients also have a shorter survival time, compared to non-demented patients, emphasizing the clinical and prognostic importance of early diagnosis of dementia in ALS.
The study, “Comorbidity of dementia with amyotrophic lateral sclerosis (ALS): insights from a large multicenter Italian cohort,” was published in the Journal of Neurology.
ALS, a neurodegenerative disease that destroys nerve cells and causes disability, also has a cognitive impairment component, ranging from mild changes to frontotemporal lobar degeneration (FTLD) spectrum disorder.
Although it has been reported that from 6 to 15 percent of ALS patients develop dementia, the association between dementia and disease onset or phenotype have not been studied extensively.
In an attempt to explore the association between dementia and clinical prognostic factors in ALS, researchers analyzed data from 1,638 Italian ALS patients, diagnosed from 2009 to 2013 in 13 Italian referral centers.
Compared to ALS patients without dementia, ALS patients with frontotemporal dementia (ALS-FTD) were significantly older at onset (67.09 vs. 64.20 years), at clinical observation (72.83 vs. 70.29 years), and at diagnosis (68.12 vs. 65.30 years).
ALS patients with dementia had a 13-month reduction in median survival rate compared to non-demented ALS patients (29 months vs. 42 months), which is in agreement with previous studies.
When the researchers examined ALS disease phenotype they found that this reduction in survival time was in patients with classic, bulbar, and flail limb phenotypes and with bulbar and spinal onsets, but not in patients with respiratory onset.
The authors also found there was an increased risk of family history of ALS and FTD, which is characterized by nerve cell loss in the frontal and temporal lobes of the brain, in demented ALS patients. However, flail leg phenotype, a condition in which patients lack mobility and sensation in their legs, and spinal onset were significantly less common in ALS patients with dementia.
The authors conclude by saying: “… findings on a large cohort of newly diagnosed ALS patients corroborated the evidence that information on cognitive impairment could further supplement the clinical characterisation of ALS patients from the early stages, integrating the current phenotypic evaluation and, thereby, leading to potential improvements both in real life and in clinical trials.”