<li><a href="#">Current Period</a>
  <ul>
        <li><a href="#">2012</a>
        <li> a href="#">2011</a> //...you get the point

<li><a href="#" class="noclick">Current Period</a> ....

$("#nav a").click(function(e){
     if ($(e.target).hasClass("noclick"))
         return false;

     // your other code here
});

$("#nav a").not(".noclick").click(function() { ...

$('.noclick').unbind('click');

$('.noclick').click(function(e){e.preventDefault();});

<a href="javascript:void(0);">Text</a>

('.noclick').on('click' , function(e) {
     e.preventDefault();
});

<li><a href="#" class="noclick">Current Period</a> ....

<li><a href="#" class="noclick" onclick="return false;">Current Period</a> ....

.noclick { pointer-events: none; cursor: default; }

.noclick { cursor: default; }

.noclick { cursor: default; }

$('.noclick').each(function() {
    var $this = $(this);
    $this.hover(function() {
        // do something...
    });
    $this.click(function() {
        return false;
    });
});