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Cognitive Effects of DM

I have an acquaintance through the DM community, I’ll call her Sarah. Sarah is very frustrated with the cognitive effects of Myotonic Dystrophy (DM) on her loved one. Sarah’s needs to get guardianship of her loved one, we’ll call him Joe. Joe isn’t co-operative with the idea. Joe is being very inappropriate with his money and he is in charge of the family business with which she is involved. Sarah has been told that if she were to try to get guardianship of Joe and wasn’t successful then Joe could retaliate and take away any of her access to the family business.

Sarah’s frustration has caused her to contact many organizations including MDA (Muscular Dystrophy Association) and MDF (Myotonic Dystrophy Foundation). From what she tells me she has been very outspoken, more so than she is used to, because she is trying to get her point across that the cognitive effects of DM need to be talked about and addressed more.

Due to my family all having DM I have studied the fronto-temporal part of the brain extensively. I have a textbook from 1998 that I have studied so much that the book is marked up and the pages are tattered. The book is The Prefrontal Cortex: Executive and Cognitive Functions by Roberts, Robbins and Weiskrantz. Because of the age of this book and its information, I did some research to find more current information and I have listed it in this article.

In my observation, one of the problems with getting a label of the effects of DM is that it is so varied in the way that DM effects each individual. My friend Sarah has quite a complicated situation with lots of inappropriate behavior and a great deal of angst between her and her loved one. And Sarah does need to continue to advocate for her loved one. Even though Sarah’s situation is frustrating and painful it isn’t possible to categorize all DM individuals because the effects of DM are varied from person to person.

My family is definitely affected cognitively and it has been a long journey getting their limitations identified and at the same time working very hard to keep their self-worth intact.

I have put together a summary and some documentation to help explain the effects of DM, but just because it is a common effect of the disease doesn’t mean that it will affect every DM individual in the same way. When you are dealing with an adult who has the right to manage his own life irrespective of someone else’s input, it’s very difficult to get the courts to help you put limitations on your loved one.

Myotonic dystrophy type 1 (DM1), or Steinert's disease, is the most prevalent muscular dystrophy in adults, affecting at least 1 in 8,000 people worldwide. It is a multisystemic disorder with effects in muscular, ocular, gonadal, cardiac, endocrine, and neurological systems. Although the congenital onset form of the disease is often associated with significant intellectual impairment, adult-onset DM1 is characterized by average or low average intelligence quotient, often accompanied by impairments in attention, memory, visuospatial and executive functions, hypersomnia, and behavioral problems

Archives of Clinical Neuropsychology, Volume 32, Issue 4, June 2017, Pages 401–412,

  • Cognitive and behavioral abnormalities can involve deficits in intelligence, executive function, visual-spatial construction, thinking and problem solving, and attention, although the scope and degree of the involvement may vary.

  • Difficulty organizing and planning.

  • Personality features such as anxiety, avoidant behavior, apathy, lack of initiative or inactivity.

  • Mental health disorders including anxiety, substance abuse, or depression.

  • Problems with social circumstances ranging from child neglect, acute financial need, unsafe driving, unsafe or unsanitary home, and/or homelessness.

  • Excessive daytime sleepiness (otherwise known as hypersomnia) which is associated with an unpredictable and frequent sleep.

Self-awareness in psycho-social activities is poor including reporting about their independence and social situations.

DM individuals present with reduced awareness of the effects of their disease and its progression, defined as anosognosia. This leads to a delay in diagnosis and treatment of their symptoms. The researchers believe that a deep knowledge of this aspect will be useful for management of patients with DM1, also for guidance in occupational and social interventions. Orphanet J Rare Dis. 2016 Apr 4

DM is a progressive muscle disorder but from a cognitive point of view DM is also characterized by progressive frontal cognitive impairment. The awareness of cognitive and behavioral symptoms may help to understand why patients with DM1 and DM2 may not function as well in their work-related and family-related activities as expected by their muscle disability. There is a coexistence of a dysexecutive syndrome.

Mental impairment, executive dysfunctioning and avoidant personality traits have been described in myotonic dystrophy types 1 and 2 due to extensive white matter involvement in all cerebral lobes, brainstem and corpus callosum. Depressed mood and fatigue are present even without predominant white matter affection (early disease stages). Sleepiness and fatigue constitute major complaints in myotonic dystrophy type 1 and type 2. Brain. 2011 Dec;134

Daytime sleepiness is a prominent complaint in DM1 patients and it is not the result of sleep apnea and probably represents a direct effect of CNS lesions. Daytime sleepiness occurs without ventilator impairment possibly due to an association between sleepiness and brain stem abnormalities. Archives of Clinical Neuropsychology, Volume 32, Issue 4, June 2017, Pages 401–412,

Functional brain abnormalities may account for the atypical personality traits observed in patients with DM1.

There is a presence of social anxiety, solitude, and eccentric behaviors in a proportion of those with DM although none demonstrated any impairment of reality on test results. There is no correlation with the severity of DM and the Muscle Impairment scores or age. JAMA Neurol. 2014;71(5):603-611. doi:10.1001/jamaneurol.2014.130

There is a Myotonic Foundation dedicated to research, care, and potentially a cure for DM. You can find them at . They are passionate about helping professionals along with those living with DM and their families. Feel free to reach out to them for any validation of my above listed information.

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