By: Susan Woolley, Ph.D. Neuropsychologist.

Dementia in ALS AmyandpALS

For a minority of pALS, the disease affects thinking, not just muscles.  It is estimated that 15% of pALS experience dementia, which is called Frontotemporal Dementia (FTD).  Family members often notice this before the person with ALS.  Sometimes it causes dramatic changes in personality, resulting in unusual interactions with others.  A person with FTD may suddenly do things that are very out of character, or they may appear to stop caring about the feelings of others.

Dementia in ALS 2 AmyandpALS

“How can you not know that I am getting angry?”


pALS with FTD often are not aware that they have changed or that they are having problems with other people.  For other pALS, language is more affected than behavior.  They may not say or write sentences correctly, or they may have a lot of problems with words.  This is different from the normal word finding difficulties that we all have in day-to-day discussions.  It is also different from dysarthria (i.e., slurred speech), which is caused by muscle weakness and not dementia.  Neuropsychological testing can be completed to determine whether dementia is present in a loved one.  This type of assessment can also provide recommendations for caregivers so that the brain changes are more manageable for pALS, caregivers, and family members.  It is important to know whether someone has dementia, since it can impede the use of recommended devices and alter treatment decisions.