Study finds gender differences in pathophysiology of Parkinson's disease

Not only do women appear to be better protected than men from Parkinson's disease, the associated pathophysiology also shows gender differences. This is a finding of a study from Slovenia, presented at the Congress of the European Academy of Neurology in Lisbon.

Parkinson's disease progresses differently in women than in men. A current study has now furnished the first neurophysiological evidence supporting this finding. "Numerous demographic studies have provided evidence that men contract Parkinson's disease nearly twice as often as women. What was unclear, however, was whether a gender-specific pathophysiology exists as soon as the first symptoms appear," Dr Maja Kojovic (Ljubljana) explained at the 4th Congress of the European Academy of Neurology (EAN) in Lisbon.

The international research team proceeded from the concept that in early Parkinson's disease functional changes can be detected in the primary motor cortex (M1) using transcranial magnetic stimulation (TMS). If pathophysiology differs between genders in PD, they hypothesized that this will be reflected in differences of M1 TMS measurements.

Thirty-nine newly diagnosed and untreated Parkinson's patients (23 males, 16 females) were assessed using the Parkinson's Disease Rating Scale (UPDRS), a comprehensive instrument for assessing disease-related impairments in connection with Parkinson's disease. Then the patients and a group of healthy control group underwent TMS measurements for the following parameters: motor thresholds of the brain, input/output curve (IO), short interval intracortical inhibition (SICI), cortical silent period (CSP) and intracortical facilitation (ICF). Brain plasticity was also measured using paired associative stimulation (PAS).

The UPDRS tests did not yield any differences in motor scores between the genders. However, the female patients had a less steep input and output curve (IO) than the male patients on the side of the brain more affected by Parkinson's disease.

The women with Parkinson's disease also exhibited better preserved short interval intracortical inhibition (SICI) in both hemispheres compared to affected men and tended to have a better response to the PAS protocol on the side less affected by symptoms. No gender-specific differences were determined, however, in the motor thresholds, intracortical facilitation and the cortical silent period. The healthy control group did not show any gender or interhemispheric differences for any one of the transcranial magnetic stimulation parameters measured. "The detected gender differences in corticospinal and intracortical excitability in patients with early untreated Parkinson's disease represent differences in disease pathophysiology. Gender may also prove to be a relevant factor when choosing appropriate treatment", Dr Kojovic commented.