Highlights from the neurodegenerative disease sessions

Subtyping aphasia matters

The Copenhagen meeting heard several presentations supporting this classification. First, patients in the three disease subtypes differ in risk of developing behavioural disorders. Work from Australia suggests such problems are more common in patients with the semantic variant. Secondly, the aphasia subtypes differ in imaging and pathophysiological features. For example, the logopenic patients have demonstrably high amyloid load while the other subtypes do not, supporting its link with AD.  

So, from the point of view of patients and carers wanting to know about prognosis, as well as that of the neurologist, it is helpful to distinguish between these subtypes of PPA.

Amyloid PET changes diagnosis

A naturalistic study in patients with cognitive impairment shows that having information from amyloid PET is likely to alter diagnoses made on purely clinical grounds and results in corresponding changes in management plan. 

Daniele Altomare and colleagues looked at 228 consecutive patients diagnosed in 18 centres in northern Italy. Thirtyfive percent of patients diagnosed clinically as having AD did not in fact have amyloid pathology. And amyloid was present in 48% of the patients diagnosed with non-Alzheimer’s dementia. In half of the latter group, the diagnosis was changed in the light of PET data. 

There were also changes in the confidence of diagnosis, and in treatment. Particularly evident was the likelihood that cognition-specific agents -- cholinesterase inhibitors or memantine -- would be used in those who were amyloid PET-positive, even though the clinical diagnosis had been non AD.

These data are similar to those from Philip Schelten’s group in Amsterdam.

Tremor in PD

Tremor is present at diagnosis in around 50% of Parkinsons’ Disease (PD) patients. It is embarrassing, and interferes with routine activities. Drug treatment, though helpful for bradykinesia and rigidity, is not very effective in controlling tremor. Deep brain stimulation can alleviate the condition but is expensive and associated with high complication rates. 

So there is interest in the new, non-invasive technique of MRI-guided ultrasound thalamotomy. Lesions are produced by gradual focal heating monitored by imaging. 

Ilana Schlesinger and colleagues at the Rambam Healthcare Campus, Haifa, Israel, treated 40 patients with either essential tremor or PD tremor refractory to treatment. All but one were tremor-free in the contralateral arm at the end of the procedure. In the majority of PD patients, tremor had not returned at one month, and improvement was seen in quality of life. Outcome in essential tremor patients was similar. Adverse events were mild and transient. These results, though preliminary, are sufficiently promising to justify a large randomized trial with a sham procedure as control.

Impulse control

Around 57% of the variance in incident impulse control disorders is accounted for by genetic factors, according to Julia Kraemmer and colleagues from the Hôpital Pitié-Salpêtrière, Paris, France. They followed 276 de novo patients from the Parkinson’s Progression Markers Initiative cohort, 86% of whom were started on dopamine replacement therapy (DRT). This was a dopamine agonist in 40% of cases. Over the course of the study, 19% of patients developed problems with impulse control. 

Combining  information from 13 gene variants with clinical factors such as age and exposure to DRT improved their ability to predict ICD. In future, this combined genetic/clinical approach may guide selection of drug therapy in vulnerable patients. The polymorphisms identified as underlying genetic risk may also help us develop new treatment strategies.