The implications of disease coexistence

In order to better counsel patients, it is key for clinicians of different disciplines to be aware of, and diagnose, the 'overlap syndrome' between two medical disorders - ALS and FTD - since it significantly affects patient survival. In her new study, Catherine Lomen-Hoerth, from the University of California San Francisco in the US, also highlights that from a research perspective, identifying the syndrome early is an opportunity to study damaged nerve cells and understand more about the early stages of both ALS and FTD. Her work is published in Springer's Journal of Molecular Neuroscience, in a special issue entitled Frontotemporal Dementias, which contains 56 studies on this topic.

ALS, or amyotrophic lateral sclerosis, is a progressive, fatal disease causing weakness of the voluntary muscles of the body. FTD, or frontotemporal dementia, is the second most common early-onset dementia after Alzheimer's disease, caused by the degeneration of the front part of the brain which may also extend to the back of the brain; it is characterized by behavioral changes and language difficulties. Up to 15 percent of FTD patients and 30 percent of ALS patients experience the overlap syndrome (ALS-FTD). However, it may be difficult to identify because patients either attend a neuromuscular clinic or a memory disorder center, each with limited expertise in the other's specialty.

Lomen-Hoerth's paper argues that early detection of this syndrome is critical since it greatly impacts survival, and requires adequate patient counseling. It presents the clinical characteristics of the overlap syndrome with new diagnostic criteria. It also looks at screening strategies and techniques to manage the condition.

The author concludes: "There are many important clinical and research implications for ALS-FTD. Identifying FTD patients as they are just developing motor neuron problems, even before they become clinically weak, provides a window into very early motor neuron disease. Conversely, the ALS patient with very subtle impairments can be followed as the dementia progresses. The research implications are tremendous to be able to evaluate 'sick neurons' pathologically and understand more about the pathophysiology of both ALS and FTD."